No matter how carefully you plan, life is always taking you by surprise. On a construction site it’s the same, like what happened on our [Old Foundry project](https://www.houseup.co.uk/news/conversion-victorian-building-intelligent-construction) site. Unexpected findings can break your day and the only way to win is to find the bright side of things!  
So if life gives you a steel beam in the middle of a staircase opening, well, don’t make lemonade!

Note: now that the project is complete, you can have a look at the final result [here](https://www.houseup.co.uk/portfolio/the-old-foundry-conversion).

A Beam Is Found Where The Architects Designed A Staircase Opening: A Cost And Time Effective Solution
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While creating the opening for a staircase, we found an existing steel beam not shown in the drawings as it wasn’t visible before the stripping out.  
A decision was made on-site after the real time assessment of our structural engineer. He foun d it was safe to remove the beam and place it in a different position coherent with the rest of the design, without compromising the stability both during the alteration and in the final result.  
By having a structural engineer on site we can skip the standard procedure of interrupting the work, contacting the architects, arranging a site visit with the original structural engineers and wait for them to produce a new design.  
Our client saved time and avoided the additional cost of the involvement of the architect and the original structural engineer.

![SteelBeamPlacementStaircaseJoists.png](/uploads/Steel_Beam_Placement_Staircase_Joists_e764aa4f40.png)

The Joists Run In The Opposte Direction That The Architect Assumed In Their Drawings
------------------------------------------------------------------------------------

When creating an opening for a staircase, we found that the direction of the joists assumed on the drawings was wrong. This is not uncommon as the joists are not usually exposed during the design phase.  
One of the solutions could be to cut some of the joists and add an extra steel beam to support them. In this particular case, this wouldn’t be ideal, because the beam would be visible inside an adjacent extension with sloped roof and even outside of the sloped roof itself. Alternatively, a column would be needed in the middle of an open space.  
In a standard situation, the original structural engineers would need to inspect and provide new drawings according to the newly found situation. In our case our engineer assessed the situation on-site and managed to create a brilliant alternative: using an existing internal wall to bear the load of the cut timber floor joists, we solved the problem with a small alteration to the original wall to make it load bearing, that is, by building it with concrete blocks.  
We avoided delays and the additional cost of a steel element, plus we implemented a solution that did not deteriorate the habitability and aesthetics of the room.

Structural Frames And Other Solutions When Replacing A Wall With Glazing
------------------------------------------------------------------------

The initial design included the creation of a wide opening at the back of the building that required a steel frame to provide additional support. The structural elements were two horizontal beams and two additional columns positioned at the sides of the opening and supported by new pad foundations.  
After exposing the walls and inspecting the foundations, we realised the additional foundations and columns were not required. We applied structural design optimisation, bolting the horizontal beams to the lateral walls. That way we achieved the right vertical load distribution and we also increased the horizontal stability by connecting the two walls.  
Through our optimisation, our client saved money and reduced the amount of work required.

![sketch-4A.jpeg](/uploads/sketch_4_A_b7159d8867.jpeg)

Regular Inspections Of Existing Structural Elements, Included Brick Walls, Prevent Future Costly Problems
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During a site inspection we realised the external brick-walls were in poor condition. We decided to strengthen the existing walls and stop the deterioration of the bricks by using rich mix sand and cement render on the external face of the walls. This method enhances the performance of brick masonry walls, increases their shear strength and the overall structure’s performance. Without a structural engineer on-site, that might go unnoticed by the builder and eventually compromise the quality of the final result; in alternative, a structural engineer would need to visit the site to create a conditional report with remedial recommendations.

Learn how houseUP were able to complete a challenging victorian conversion after finding out the external brick-walls were in poor condition. Read more.

Structural Challenges of Victorian Conversions | houseUP

The Old Foundry: Lessons Learnt From The Conversion Of A Victorian Building

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Renovations, extensions or even whole new constructions can work wonders in adding a zero or two to any property’s price. But with budget and time spans an ever-present concern, it can be difficult to know which home improvements are the most effective in increasing the value of your home.

In general, anything which creates more liveable space and a higher quality of life for the house’s inhabitants is a sure-fire way of boosting the property’s price tag. Here are a handful of ideas for those looking to implement home improvements, enhance their enjoyment of the space and increase the market value of their assets all in one fell swoop.

Independent living space
------------------------

Whether it’s converting an existing space, enlarging its dimensions or creating one entirely from scratch, an area that is completely independent from the main property is guaranteed to add value to your home. One typical way to achieve this is through a [basement conversion](https://www.houseup.co.uk/services/basement-conversion-london) with its own separated access point.

The new space can then become an office or a small independent flat which can be rented out, creating a source of income which can go towards repaying for the works more quickly and negating the need to sell. It could also be used by a member of the family who needs to stay close while still maintaining their own self-sufficiency, such as an elderly relative or teenager. Whatever the final purpose of the space, it will undoubtedly increase the potential selling price of the property.

### Improving energy efficiency

Any kind of refurbishment geared towards increasing energy efficiency will have the doubly beneficial effect of lowering the running costs of the property on the one hand and increasing its selling price on the other.

Some suggestions for energy efficient home improvements include: a more efficient heating system, such as a new boiler, underfloor heating or infrared heating; new window fittings with better glazing and more efficient insulation; energy efficient lighting and electrical systems; Smart devices to automate and optimise the use of appliances and central heating; and enhanced ventilation and insulation techniques to minimise heat loss.

### Family spaces

Home buyers with families, especially those with small children, are often willing to pay higher property prices for a home that was obviously designed to cater to their needs. With that in mind, any improvement to or enlargement of the family spaces are beneficial. [Rear and side extensions](https://www.houseup.co.uk/services/house-extension-london), for example, are very affordable and can add nice living space to an existing kitchen, or can be used to create new rooms full of light.

These can become playrooms for the children or small dens for leisure time to be spent with the whole family. Even without extending, often new living space can be created simply by rearranging the existing space and optimising its layout. A trained professional can provide unique insight and advice on this subject.

### Bathroom or kitchen renovations

Certain rooms of the house – especially the bathroom and the kitchen – lend themselves more readily to renovation than others. This is because of the availability of sleek, modern appliances that are specifically designed to offer intuitive solutions to everyday problems, often for a price which won’t break the bank.

Indeed, it’s common for bright furnishings and intelligently-designed appliances to be available for very affordable prices. Even the smallest touches can add to the quality of life for the home’s inhabitants and make the property appear special and unique in the eyes of a potential buyer.

Find out some of the best ways to increase property value in 2023, whilst being cost efficient. This guide has a variety of renovation and improvement ideas.

What Home Improvements Add the Most Value? | houseUP

What home improvements add the most value?

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When your neighbour is planning to do building work that involves a party wall, they are required to serve a party wall notice to the owners of adjacent buildings.

Your rights when receiving a party wall notice
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When you receive a party wall notice, it is your right to appoint a party wall surveyor to act on your behalf.

**The fees for your party wall surveyor are paid by the building owner who is planning the building works,** if the building works are solely for their benefit.

> [Find a party wall surveyor in your area](https://fpws.org.uk/find-a-surveyor-2/).

The party wall surveyor will liaise with the other party and put forward your preferred outcome. They will create an award that agrees in writing on details like:

* the work that will be carried out
* when and how the work is to be carried out, for example to minimise the inconvenience caused by noise, dust etc
* any additional work required or measures to protect from damage
* the condition of the adjoining property before the work, so that any damage can be monitored and fixed
* access for the surveyors to inspect the works as may be necessary

Remember that the surveyors have a duty to resolve matters in a fair and practical way!

Works that require a party wall notice
--------------------------------------

Works that require to serve a party wall notice are:

* new building on or at the boundary of 2 properties
* work to an existing party wall or party structure
* excavation near to and below the foundation level of neighbouring buildings

In practice, it means your neighbour might be planning to:

* build a new wall on or at the boundary of 2 properties
* cut into a party wall
* make a party wall taller, shorter or deeper
* remove chimney breasts from a party wall
* knock down and rebuild a party wall
* dig below the foundation level of your property

More information on the Party Wall etc Act 1996
-----------------------------------------------

You can find detailed guidance on how the party wall works on the official pages from the Ministry of Housing, Communities & Local Government [here](https://www.gov.uk/government/publications/preventing-and-resolving-disputes-in-relation-to-party-walls). The resources also include an [explanatory booklet](https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/523010/Party_Wall_etc__Act_1996_-_Explanatory_Booklet.pdf).

On our website, we have detailed guides on [Party wall agreements for loft conversions](https://www.houseup.co.uk/news/party-wall-agreement-loft-conversion) and on [How to plan building works that don’t require party wall agreements](https://www.houseup.co.uk/news/do-i-need-a-party-wall-agreement-maybe-not).

Get in touch with us for introductions to recommended party wall surveyors in your area

Know what to do if you receive a party wall notice from a neighbour. It's important that you do not ignore it. Find out the correct process in this guide.

What to Do If You Receieved a Party Wall Notice  | houseUP

I received a party wall notice from my neighbour, what should I do now?

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Creating a basement under a building can be quite traumatic for the existing structure: you need to create a void under it! This can cause disturbance to the stability of the outstanding building and the neighbourhood.

Before the design phase, you need to gather all the data needed for the calculations to be accurate and the structural elements to be designed correctly. But a good design is not enough.

It is quite intuitive that excavating a basement is challenging even when following a very reliable structural design on paper. It is paramount that not only the instructions are correct, but also that they are followed and performed in a professional, accurate, strict and precise way.

## houseUP recommendations when building a basement:
To get the structural design from a qualified reliable structural engineer
To choose a construction company (and not just a building contractor) and that you are guaranteed the presence of a structural engineer on site during the crucial phases of the work.

To check that architects, structural engineers and builders have the required professional indemnity insurance coverage for basement design and construction
Jenga Game removing a block

## General guidelines for basement projects
Before starting any design or construction works a site investigation is essential for a basement job according to the approved Documents Basements for Dwellings.

Soil Test is important to establish the ground conditions, soil types and characteristics, the level of the water table and the presence of any contaminants. This survey tells us which soils are strong and well drained and which ones are weak and not well suited for building sites.

In addition, before starting a basement project it is vital to check that the works will not affect any public services or utilities, London underground and that there are no nearby trees that will be affected by the works.

The structural design of the basement, walls and bases, the design of all necessary temporary works, and the sequencing of the construction will take into account all the geotechnical aspects recorded, and also the locality of the adjoining properties. The formation of the basement walls and bases will be made in a sequential underpinning pattern adopting construction legs no wider than 1.20m, this will avoid undue stresses being applied to the walls being underpinned.

All the basement construction works must follow a Method Statement which has to be detailed enough to explain step by step how the works should take place. This is to ensure the stability of the house above and the neighbouring properties.

A structural engineer must be on site on a regular basis to check that the builders are following the drawings, specifications and method statement.

Get in touch with our team about your basement conversion. You can book a free site visit and a free quotation from our specialists

Excavating a basement requires technical knowledge, and specific indemnity insurance for architects, engineers and builders. Learn more at houseUP.

Creating a Basement is Not a Jenga Game | houseUP

Creating a basement is not a Jenga game

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How much should you be paying for a loft conversion? This price guide dives into the cost of extending the space in your roof and building your dream loft.

How Much Does a Loft Conversion Cost? 2024 Guide | houseUP

How Much Does a Loft Conversion Cost? A 2024 Price Guide

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<p>Understanding how the costs add up enables you to make the most out of your planned investment. In this price guide we will provide you with all the elements and variables to make the best decisions when investing in a <a target="_blank" rel="noopener noreferrer" href="https://www.houseup.co.uk/services/loft-conversions-london"><strong><u>loft conversion</u></strong></a>.</p><div><div><div><div><div><div><h2>How much does a loft conversion cost?</h2><p>Depending on your location within the UK, the price of a loft conversion will vary. Furthermore, the type of conversion and the legal and technical constraints placed upon it will also play a key role in determining the likely cost. Excluding likely finishes such as windows, flooring, and sanitary ware, the typical cost of a loft conversion will cost between £2,400 and £4,000 per square metre.</p><p>The variation in the cost per square meter depends on the type of loft conversion, the size of the alterations to the roof, the access, the type of finishing and the location.</p><p>Special projects to develop the roof space in period buildings can require higher investments. In prime locations, they can double the value of a property after they’ve been completed, like this <a target="_blank" rel="noopener noreferrer" href="https://www.houseup.co.uk/news/roof-conversion-with-grass-terrace-in-chiswick"><strong>roof development project in Chiswick, London</strong></a><strong>.</strong></p><h3>ROOFLIGHT LOFT CONVERSION</h3><p>It requires the installation of rooflight windows in the roof to allow sunlight to enter the loft. It usually includes strengthening of the existing floor, flooring, insulation, plasterboarding and installation of rooflights. They are generally allowed under permitted development outside conservation areas and other designated areas. For more information on permitted development rights for householders you can visit <a target="_blank" rel="noopener noreferrer" href="https://www.gov.uk/government/publications/permitted-development-rights-for-householders-technical-guidance"><a target="_blank" rel="noopener"><strong>the official government web site.</strong></a></a>&nbsp;<br>With a rooflight conversion you keep the alterations to a minimum. This means the result will be basic, without budget for plumbing, extensive electrical work etc.</p><p>The average rooflight loft conversion cost in the UK can be between £40,000 to £60,000.</p><h3>DORMER LOFT CONVERSION</h3><p>This consists of a boxed-shape structure that replaces one of the slopes of a pitched roof. The result is a flat-roofed space that allows the installation of full-sized windows and the use of full-height furniture and other appliances. They are sometimes allowed under permitted development when not in designated areas.</p><p>The cost is higher than that of a roof light conversion, as it requires the complete rebuilding of one roof pitch plus the full associated internal works.</p><p>The average cost of a standard dormer loft extension is between £60,000 and £100,000. For an L-shaped dormer, it can go from £80,000 to £130,000.</p><h3>HIP-TO-GABLE LOFT CONVERSION</h3><p>In end-of-terrace or detached properties, the roof slope at the end of the terrace or of the detached house is replaced with a vertical brick wall. It is combined with a dormer conversion to maximise the space. The alterations to the roof are extensive and you need to build a brick gable wall, as opposed to the stud wall needed for the dormer conversion.</p><p>The average cost of a hip-to-gable conversion is higher than a dormer extension, and can go between £65,000 and £110,000.</p><h3>MANSARD LOFT EXTENSION</h3><p>A mansard loft conversion creates a flat roof space, with four or two of the external walls gently sloped. It can extend to create an additional storey on top of an existing building. It is an extensive building alteration and it always requires planning permission.This design is the most expensive option for a loft conversion.</p><p>The average cost of a mansard loft extension can go from £100,000 to £150,000, assuming the mansard covers the extension of the loft only.</p></div></div></div></div></div></div><div><div><div><div><div><div><h2>How location can change the loft conversion cost</h2><p>When discussing the topic of building works, there is no one-size-fits-all. This is reflected in the costs, too. In general, building works are cheaper where the property market prices are lower.</p><p>Much of the variation is due to the nature of expensive property areas: generally they are busier, more densely built and inhabited. This translates into higher costs, for multiple reasons. For example:</p><ul><li>Building site access: in a busy metropolitan city, often there is no or very little space for parking, placing machinery, scaffolding, rubbish skips etc</li><li>Cost of labour: in a place with a higher cost of living, the workers are paid higher salaries or daily rates</li><li>Cost of materials and deliveries: because of the higher salaries, rent cost of commercial space, constraints in the size of transporting vehicles and distance from production plants, prices for supplies are higher in metropolitan areas.</li></ul><p>For a better idea of the most expensive and the cheapest areas in the UK, as an average:</p><ul><li>Scotland and South East England are the most expensive, with peaks in Edinburgh and London</li><li>Northern Ireland is the cheapest area for building costs in the UK</li></ul></div></div><div><figure><figure><p><img src="/uploads/Old_Foundry_Victorian_Conversion_Open_Plan_Kitchen_King_Post_Trusses_scaled_min_9dd67faeba.jpg" alt="OldFoundryVictorianConversionOpenPlanKitchenKingPostTrusses-scaled-min.jpg" srcset="/uploads/thumbnail_Old_Foundry_Victorian_Conversion_Open_Plan_Kitchen_King_Post_Trusses_scaled_min_9dd67faeba.jpg 235w, /uploads/small_Old_Foundry_Victorian_Conversion_Open_Plan_Kitchen_King_Post_Trusses_scaled_min_9dd67faeba.jpg 500w, /uploads/medium_Old_Foundry_Victorian_Conversion_Open_Plan_Kitchen_King_Post_Trusses_scaled_min_9dd67faeba.jpg 750w" sizes="100vw" width="750"></p></figure></figure></div></div></div></div></div><div><div><div><div><div><div><h2>Explanation of the professional fees</h2><p>When planning any building works, you will need to consider professional fees in addition to the building costs. Even if planning permission is not required, you will still need drawings of your loft conversion to be produced for the council, the building regulation officers and for the building teams.</p><p>Ensuring the drawings are produced by a professional is always a sensible approach as they minimise the likelihood of miscalculation and incorrect information. Producing and submitting unclear or incorrect requirements and measurements can cause both delays and mistakes that can be very expensive to rectify at a later point.</p><h3>PLANNING FEES</h3><p>Whilst loft extensions can often be completed without planning permission, you will still need to file for a Certificate of Lawfulness from your council. This currently costs £103 in England.</p><p>Fees for filing for the planning permission differ amongst the councils and heavily depend on the amount of work the planning authorities need to process the application. Householder applications, required for extensions and garden buildings, are around £210.</p><p>For more information on the planning process and fees across the UK, you can visit the <a target="_blank" rel="noopener noreferrer" href="https://www.planningportal.co.uk/"><strong>Planning Portal</strong></a>.</p><h3>DESIGN FEES</h3><p>For a loft conversion, you will need to produce at least building regulation drawings. For a standard loft conversion, the design fees would be between £3,000 to £6,000.</p><p>Furthermore, you will need to budget for structural calculations, such as whether a new beam or other structural alterations are required. The fee for the structural design will range from £1,800 to £3,600 for a standard loft conversion.</p><p>Design and the associated drawings produced for a loft conversion planning application, can cost between £4,800 and £10,000.</p><p>Keep in mind that design costs can vary substantially, depending on the architects you appoint and the complexity of the design A cheaper alternative is to appoint a consultant, rather than choosing an architectural practice. Alternatively you can choose to hire a design and build company, who will quote for your loft conversion including the design fees. In some cases, the planning fees will also be included in a design and build quotation.</p><h3>PARTY WALL FEES</h3><p>If your loft conversion will need building work to a wall that sits astride a boundary you will need Party Wall agreements with all the neighbours that share that party wall with you.</p><p>This is very often the case in terraced or semi detached properties, or if you are extending a flat in a block. The typical cost of a party wall agreement depends on whether your neighbours and you will want or need to appoint a party wall surveyor.</p><p>Typically, party wall agreements will cost £1000 to £1,800 per neighbour.</p><p>Keep in mind it is possible to serve the notices yourself without the need to pay for a surveyor if your neighbour agrees on the proposed work, and they don’t appoint a surveyor themselves.</p><h3>BUILDING CONTROL FEES</h3><p>You will need a Building Control certificate at completion, which certifies that all the work is in compliance of building regulations. The average cost for a loft conversion is approximately £1,000, depending on the size and the nature of the works.</p><p>You can liaise directly with the local authority or engage a government-approved inspection company. Both will check that the work is carried out in compliance and will issue the certificate at completion.</p></div></div><div><figure><figure><p><img src="/uploads/Victorian_Penthouse_Chiswick_Mansion_Block_Terrace_Grass_Clouds_800x475_657a090917.jpg" alt="VictorianPenthouseChiswickMansionBlockTerraceGrassClouds_800x475.jpg" srcset="/uploads/thumbnail_Victorian_Penthouse_Chiswick_Mansion_Block_Terrace_Grass_Clouds_800x475_657a090917.jpg 245w, /uploads/small_Victorian_Penthouse_Chiswick_Mansion_Block_Terrace_Grass_Clouds_800x475_657a090917.jpg 500w, /uploads/medium_Victorian_Penthouse_Chiswick_Mansion_Block_Terrace_Grass_Clouds_800x475_657a090917.jpg 750w" sizes="100vw" width="750"></p></figure></figure></div></div></div></div></div><div><div><div><div><div><div><h2>The loft conversion cost can increase if…</h2><p>Whenever a loft conversion project is not a standard one, costs can increase accordingly. The most common reasons why the budget can be higher than the average are:</p><p><strong>Number of parties involved in the party wall process:</strong>&nbsp;<br>The higher the number of parties involved, the higher the cost of party wall agreements. Plus, any dispute causes delays and even more additional costs.</p><p><strong>Complex structural design and implementation:</strong>&nbsp;<br>Your loft extension might need more beams or columns than the average, or the shape or the design might require specific structural solutions.</p><p><strong>Building access:</strong>&nbsp;<br>Any constraint on the accessibility of the site can significantly increase the costs.</p><p><strong>Age and conditions of the existing building:</strong>&nbsp;<br>When making structural alterations to an old building, surprises can happen while stripping out. It’s not uncommon that some of the existing joists and beam will need strengthening or replacement that cannot always be planned ahead.&nbsp;<br><br><strong>Height of the existing building:</strong>&nbsp;<br>For high buildings, like blocks of flats, the cost of transporting the materials onto the site. So are scaffolding and rubbish removal.</p><p><strong>Finishes and interiors:</strong>&nbsp;<br>Any bespoke solution has an impact on the cost of a loft conversion. High end finishes also cause an increase compared to the average costs.</p><p><strong>Project duration:</strong>&nbsp;<br>If you have tighter timelines for completion than the average, the project will need more workers on site at the same time. Delivery of materials can also be affected. This means higher logistics and organisational costs, also considering there is a maximum in the number of people who can work on a loft conversion at the same time, without interfering with each other’s work.</p></div></div></div></div></div></div><div><div><div><div><div><div><h2>How much should you spend on a loft conversion?</h2><p>When planning building works to your home, it’s important to consider how much value the alterations will add to the current property. It is recommended to consult local estate agents, to better understand the potential sale price of properties in your area where a loft extension was added.</p><p>Once you understand the increase in value that a loft conversion could add to your property value, you can use that figure to support many decisions in the course of the project. Design solutions, finishes, space, lighting etc can be evaluated and selected, according to your understanding of the investment return.</p><p>This is an excellent way to stay in control of your budget and be confident that the extension is a worthwhile investment.</p></div></div></div></div></div></div>

Electing to extend can be an excellent means of maximising the potential available space of your property, without the costly need to relocate. Generally double storey [side and rear extensions](https://www.houseup.co.uk/services/house-extension-london) are technically simple and are feasible in most detached and semi-detached houses.

Double storey extension vs single storey
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A double storey extension is an even better investment when compared to a single storey. The excavation and the roofing costs won’t change from single to double storey extension. This makes the cost per square metre of a double storey extension much lower than the cost of a single storey.

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How much does a double storey extension cost?
---------------------------------------------

The cost of a double storey extension can vary depending on:

* location
* site access
* soil composition
* size in square metres
* type and shape of the roof
* finishes like windows, rooflights, underfloor heating, flooring etc

### **Average cost of a 2 storey extension**

The current average cost of a double storey extension varies with the location across the UK, going from £2,000 to £2,500 per sqm, excluding finishes.

In London the average cost excluding finishes is higher, with figures ranging from between £3,000 and £3,500 per square metre for the building cost. However, in London the added value of extra space is also far greater, with a minimum of £7,000 per sqm of increased value.

### **What fees can I expect to pay?**

Beyond the construction cost, there are fees you need to consider and budget for when planning a double storey extension.

#### Planning fees

Double storey house extensions may, in some circumstances, proceed without planning permission.

In the case that you need planning permission,  the cost for householder applications can vary from between £200-£400, depending on your local Council   If your planning permission comes with planning conditions, you will pay £34 for their discharge.

If  planning is not required because your 2 storey extension is built under permitted development, you may still want to get a Certificate of Lawfulness from your council (approx fees £100).

You can visit the official government page that [explains planning related fees and the method of calculating them](https://www.gov.uk/guidance/fees-for-planning-applications).

#### Design fees

Architectural fees are usually between 3% and 7% of the construction cost but are typically higher in London, around 15%. For a double extension, you will need to produce at least a set of building regulation drawings, with design fees between £3,500 and £6,500. Planning drawings will be in a  similar price range.

Furthermore, you will need to budget for structural calculation. The fee for the structural design can vary from £1,500 to £2,500 for a standard structural design.

Keep in mind that the design costs vary a lot, depending on the architects you appoint and the complexity of the design. Hiring a consultant, rather than directly appointing an architectural studio may save you money..

Another cost effective option is to hire a design and build company that will quote your double extension, including all the design fees. Some design and build companies may include planning fees in their quotes.

#### Party wall fees

If your extension includes building or excavating astride or close to a boundary, you will need a party wall agreement with your adjacent neighbours. The cost of a party wall agreement depends on whether your neighbours and you will want or need to appoint a party wall surveyor.

Typically party wall agreements will cost between £1,000 to £1,800 per neighbour.

Keep in mind that you can serve the notices yourself and won’t need to pay for a surveyor if your neighbour agrees on the proposed work and don’t seek to appoint a surveyor themselves.

If you prefer to appoint a party wall surveyor, you can visit [RICS website](https://www.ricsfirms.com/glossary/party-walls/).

#### Building control fees

You will need a building control certificate at completion, which certifies that all the work is in compliance of building regulations. The average cost for a double storey extension is £950, depending on the size and the nature of the works.

You can liaise directly with the local authority building control services or contact a government-approved inspection company.

For more information you can visit the official government pages on [building regulations approval](https://www.gov.uk/building-regulations-approval).

#### Other consultants’ fees

It is possible that you may need to appoint other consultants, according to the circumstances, for example:

* a survey of the existing building
* a tree report: if you need to move, remove or replace a tree
* flood risk assessment: if you are in an area where floods are possible
* ecology report: if the authorities think your construction work may affect the local wildlife
* archeological report: if your house is inside or close to an archeological area
* historic building report: if your house is a listed building or is located inside a conservation area

The cost may vary, depending on the agency or the consultants you will hire.

![house-extension-gantshill-facade-double-front-door-white-render-black-details.jpeg](/uploads/house_extension_gantshill_facade_double_front_door_white_render_black_details_3b680cc7c4.jpeg)

### **Cost of fitting out your double storey extension**

Overall, the average building cost of a double storey extension varies across the UK, going from £2,000 to £3,500 per sqm.

The price of the fit out depends heavily on the usage you’re planning for your extension and the quality of the finishes you are choosing.

Make sure you understand the breakdown of the costs, so that you can invest your budget on your priorities.

#### General

Plastering plus painting costs can go between £40 and £60 per square metre, depending on the type of paint.

Supply and fit of the flooring depends on the cost of the flooring itself. As an average, it can go between £60 and £180 per square metre and more, if the flooring is very expensive.

The cost of the heating is very variable, with underfloor heating being the most expensive option, which can go from £80 to £150 per square metre, including the materials.

You might need to change your boiler to accommodate the additional needs for a bigger area. It may cost from £2,500 to £4,000.

#### Downstairs

The supply and fit of a kitchen can rise steeply in price, depending on the kitchen and fittings you choose. The minimum budget should be at least £5,000, with a good size and quality kitchen to be between £15,000 to £25,000, including the plumbing.

The cost of bifold or sliding doors will depend on the size of the opening and the chosen product. The price can vary between £1,800 and £3,200 per linear metre.

Upstairs

For bathrooms or wet-rooms, you will need to budget for at least £5,000. The cost can rise considerably , based on the quality of the finishings like sanitary ware, shower screens and trays, taps, tiles etc.

### **Will a double storey extension add value to my home?**

In the short term the build costs may, in some locations and properties, minimise the immediate added value. However, given both the improvement in scope and size to the property, the alterations can still work out cheaper than the cost of purchasing and subsequent move to a larger house.

If you are planning to sell and your house is not in excellent condition, a prior renovation can increase your asking price. At this point you can include a double storey extension, as the cumulative price will be lower than doing the renovation and the extension at separate times.

In general, double storey extensions are the cheapest extensions per square metre. In London, for example, they usually cost between £1,800 and £2,800, while the property price per square metre in the cheaper London boroughs would be around £4,000 per square metre.


Planning and regulations for a double storey extension
------------------------------------------------------

It is possible that a double extension falls under permitted development rights.

### **Do I need planning permission for a double storey extension?**

Although the options for a double storey extension are more limited than a single one, planning permission is not always needed.

#### Permitted development rights

To build a double house extension you will need to stay within the constraints below:

1.  **Area**: the area of extensions must be less than 50% of the total free area around the house
2.  **Appearance**: the exterior appearance must blend in with the existing house and the neighbourhood
3.  **Width**: the width must be less than 50% of the width of the existing house
4.  **Length**: the max length of rear extensions is 3m for terraced or semi-detached houses, up to 4m for detached houses
5.  **Height**: for 2 storey extensions, the height must not exceed the height of the existing house eaves. Only single-storey extensions are allowed under permitted development, if the distance to the boundary is less than 2m,
6.  **Balconies and terraces**: they are never allowed within permitted development rights

Rules for permitted development are stricter in designated areas.

#### Certificate of lawful development

Even if you don’t need planning, it’s good to obtain a certificate of lawful development from your council, after the completion of the work. This will certify that you built within the constraints of permitted development.  
The council fee for the certificate of lawful development is £103.

#### Applying for planning permission

If your extensions cannot be built under permitted development rights, you will need to file for a planning permission.  
Depending on the complexity of the proposed work, the process might also include pre-planning.

Appointing an architect is one option, which is cheaper with a freelancer. Another way is hiring a design and build company, which is often the most cost effective approach.

#### Does a two storey extension need to comply with building regulations?

All building work needs to comply with building regulations. Professional building companies engage with the local building control officers or with a certified private agency during the project. At completion, they’ll provide you with a building regulation certificate.

#### Do I need a party wall agreement for a 2 storey extension?

You need a party wall agreement if you are building or altering a wall that sits astride a boundary with an adjacent property.  
When excavating the foundations for your double storey extension, a party wall agreement is needed when you are building the foundations up to 6m away from the boundary, depending on the depth of the foundations.

#### How big can my double storey extension be?

Planning rules include limitations on how big a double storey extension can be.

##### Height

The height of a 2 storey extension must not exceed the existing roof eaves.  
If the resulting ceilings are too low, there are possible solutions, like excavating a few centimeters at the ground floor. Leaving exposed joists at the upper floor is a good option to give a feeling of space and air, even when the actual height is lower than ideal.

##### Footprint

Planning rules limit how far a two storey extension can project. If your neighbours have window openings towards the proposed extension, there are limitations to prevent a loss of light to the neighbours. The extension must project no further back than a line set at 45 degrees horizontally from the centre of neighbouring windows.

### **How long does a two storey extension take?**

The time it takes to complete a two storey extension can vary a lot. External factors are especially difficult to estimate, like planning and party wall agreements.  
It is possible, though, to evaluate average times for each preparation phase. The duration of the construction, on the other hand, is easier to estimate.

#### Planning time

* Design: 8 weeks
* Planning: 8 weeks to 3 months for a successful planning process

#### Preparation time

* Party wall agreements: from 2 weeks to months, depending on how difficult the negotiation
* Technical drawings, building regs, structural design: 4 to 8 weeks

#### Construction time

As an average, the construction of a double storey extension takes 14 to 16 weeks, depending on the size. This might sound a lot, but it is important to give each phase the appropriate duration for the best results:

* Excavation and foundations: 1 to 3 weeks
* Structural beams and columns: 1 week approx
* External walls: 2 weeks approx
* Ground floor slab and 2nd storey suspended timber floor: 1 week approx
* Roof: 2 weeks approx
* Dry lining and plastering: 2 weeks approx
* Electrics and plumbing: 1 week approx
* Decoration and painting: 1 week approx
* Flooring, skirtings, windows, doors and other joinery: 2 weeks approx

![front-and-rear-elevations.jpeg](/uploads/front_and_rear_elevations_57ffa2ebb9.jpeg)

Types of double storey extensions
---------------------------------

According to the relative position to the existing building, there are different types of double storey extensions

### **Two storey rear extension**

It’s an extension at the back of a house, often in the garden. It’s a good option for detached and semi-detached houses. A terraced house extension at the rear of a property is also sometimes feasible.

### **Two storey side return extension**

It uses the narrow space at the side of a house, without using up garden space. It’s a great option for a ground floor extension, to implement a change of character on a ground floor without compromising the back garden area. This is an option for a semi-detached or detached house extension. Keep in mind that neighbouring properties with overlooking windows might limit this option

### **Two storey wrap around extension**

It’s the combination of rear house extension and side extension. It can be a very big addition in size to the existing house. It’s feasible for a semi-detached or detached house extension.  
This is the optimal solution to maximise the added space to the existing property.

### **Two storey front extension**

This is the least common type of 2 storey extension. Extending at the front has the biggest impact on the appearance of your house. In all councils this means stricter rules to what alterations can be made.  
It can still be feasible, especially for detached houses with a large front garden.

### **What direction should I extend?**

There isn’t one right answer to this question, Usually the easiest option is extending to the rear, if the garden is big enough. Side extensions can be a great option, when there are no windows from the neighbours’ side.  
If your neighbour wants to do a side extension as well, you might consider the option of filing a planning application together, to use up all the space between the two buildings.  
Having a good architect on your side will help you understand all the options and make the best decisions on the direction of your 2 storey extension.

Designing a double storey extension
-----------------------------------

Doing a 2 storey extension is not only about space. The way you design the space must meet your priorities.

### **Interior layout of your double storey extension**

Depending on whether you are building a kitchen, a bedroom, a shower room, a playroom, the requirements will be different, and small details can make a huge difference as well.  
Given the financial outlay and potential disruption such projects can cause, it is always wise to hire professional designers and a building company to ensure the smoothest possible outcome.

#### Downstairs

Building a double storey extension is an opportunity to improve the layout of the existing spaces. If you are planning a kitchen extension, you might create an open-plan living room or a larger dining space to entertain family and friends.

An extension is also a good opportunity to make space for a utility or a laundry room in addition to the enlarged rooms. Avoid wasting space in hallways and corridors.

A smart placement of the columns will be very important in ensuring uninterrupted open plan space.

#### Upstairs

What would you like to achieve with your new space upstairs?  
If you are building a new bedroom, for example, the height of the ceiling may not be as important as in the living room. Make it an ensuite, if possible, as ensuite bedrooms are an added value to a property.

Remember there are building regulations on the size of staircases, landings, corridors etc. Make sure you seek advice from a professional for the layout design, to avoid issues that may become evident towards the end of the project, when they are costly to resolve.

### **Exterior materials of your double storey extension**

Choosing matching materials for the exterior is the easiest option, especially for the planning. When it is not possible, one good option is to design in contrast with the existing building.  
All glazed or naked concrete extensions can result in a stunning contrast for period properties.

Having a good architect or designer on your side means you will be able to understand all the options and choose the best for you: the right creative design can completely transform a property.

### **Doors and windows of your double storey extension**

The positioning of doors and windows is very important for a double storey extension, as it often requires the loss of the existing openings.  
The windows should either match the existing or be chosen in contrast.  
Bi-folding or sliding doors, roof lights, glazed walls and structural glass are all options that a good architect will help you evaluate to get the best for your priorities.

### **The roof of your double storey extension**

The design of the roof of a 2 storey extension will be subject to planning requirements, but there are still options to make the best choices.  
If there are properties around you that will overlook the roof of your extension, a green roof could be a great option to get through the planning.  
If the roof surface is not visible from the ground floor level, you can choose a flat roof, making sure that the visible parts still blend in with the existing building.

### **The indoor-outdoor link**

Doing a two storey extension is also an opportunity to get more daylight in and to create a link between inside and out. This will enhance the sense of being immersed within your garden, even if the weather does not permit.

Bi-folding or sliding doors to the garden are a great way to achieve that. Glazed walls and structural glass are all options that a good architect will help you evaluate to get the best for your priorities.

**Get in touch with us for a chat, a free site visit or a free quotation from our specialists in double storey extensions. We can help with rear and side 2 storey extensions for terraced, semi-detached and detached houses.**

Learn about double storey extensions with this 2023 guide. Including costs, planning permissions, regulations and more. With houseUP, a London based company.

Double Storey Extension Guide | 2024 Costs & Tips | houseUP

Double Storey Extensions: The Comprehensive 2024 Guide

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Vinz is the CEO and co-founder of houseUP. He is a true authority in financial planning and risk management, coming from years of working in financial services and digital payment industries

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