Trimble Architects

RIBA Architectural Services

Phone Number: 020 8538 9303

Mobile Number: 07785711635

Are you looking for wrap around extension architects in London? Our RIBA local architect services works throughout Hounslow, Twickenham, Richmond, Kingston Upon Thames, Teddington And Throughout London.

Wrap Around Extensions

For those who have outgrown their London home or property and are desperately searching for ways to add additional value to sell it shortly or remodel it for your aesthetic pleasure, we recommend looking into wraparound extensions as a solution. 

Our London-based architects at Trimble Architects Ltd have impressive years of experience in the field of house extensions and, therefore, plenty of knowledge of single-storey, wraparound and side return extensions throughout various locations. Our trade focuses on Kensington, Chelsea, Merton, Elmbridge, Kingston, Lambeth, Wandsworth and Croydon.


Wraparound extensions are much like a collaboration of rear and side counterparts that collectively form an 'L-Shape' wrapping around the two sides and rear wall of your household or property. 

You can generally opt for single or double-storey wraparound extensions to expand the back and adds extra width to your building.

It matters not whether you're searching for a dining area, utility room or new kitchen extensions; wraparounds are ideal solutions for those wishing to create a more open-plan kitchen or open-plan living space. 

We have good architects on board that will ensure they are thoughtfully designed to become a central statement throughout your home, ensuring they are modelled with love, care and innovation. 

Our in-house structural engineers will work with you closely, collaborating on numerous good design ideas and offering advice on how best to navigate the design process to achieve planning permission and compliance with building control. We'll be right by your side the entire process through to the completion of construction.

No matter the type of extension that interests you, Trimble professionals will always be here to offer various extension ideas that would best suit your property and its structural integrity. On our page, you will find our contact details. Get in touch today to speak to our specialist advisors for free quotes and more information.

What is a Wrap Around Extension?

A wraparound extension is a hybrid of side and rear building work that creates an L-shape towards or around the back of your property. 

As mentioned in the name, the wraparound practically wraps itself around two specific sides of your household on one side elevation, going around rear extensions at a single or double height. The purpose of such a build is to add extra width to your property.

The wraparound extension could add around 15-60m2 of new space to your home or garden; however, this will predominantly depend on the size of your site or land. These builds are most suitable for ground-floor flats to add extra width, yet if this is the build for you, you may want to obtain further permission for a License to Alter.

How much will a Wraparound Extension cost?

Each extension that our Trimble architects design is incredibly unique, and therefore, it can be challenging to issue a more general cost that suits one or multiple types of extensions. 

However, we can offer some guidance on the matter; for example, wraparound extensions are often some of the largest extensions that professional builders and structural engineers can form, and this is because they utilise the dead space from two specific areas. 

They also require extensive structural calculations and labour to complete as the new build supports your current property and helps create an entirely new one at its rear. Typical wraparound structures on existing London properties with a width of 4.5m and room length of around 8m will often cost at least £70-80K to build.


Regarding the design fees, Trimble Architects Ltd provides its London area customers with an efficient design package that allows our architects to provide architectural design drawings, help with planning permission, curate planning applications and the building regulations approval pack, including the necessary structural details.

Packages of such kind often cost within £3-4K for ground-level wraparound extensions. It is our responsibility to assist you in developing your design and planning drawings, that way, we can ensure what suits your budget and the themes or aesthetics you wish to opt for. We can also ensure that whatever we design fits the necessary building regulations of your desired area.

You can experiment with a combination of transformative options and unlimited amendments by selecting an architecture package and working with our qualified, creative professionals. 

Once you and our staff have curated some basic floor plans, we'll recommend some high-quality professional builders to discuss budget estimates that accurately suit each design choice and calculate a final cost. With Trimble Architects Ltd, you'll move smoothly throughout the process to create a proposal that matches the feasible planning policy regarding your budget.

Frequently Asked Questions about Wraparound Extensions

On the one hand, the designing stage of any extension projects within your desired area can be an exciting venture; however, the most challenging part tends to be the project's budgeting and general construction costs. Take a look at your design brief; this is what the general cost of your project will depend on.

Wraparound extensions are one of the most significant extensions, typically attached to the side and rear of your original building or home. The typical cost of your square metre wraparound extension is usually around £2000-£3000. However, larger wraparound extensions can cost anywhere around £40,000-£180,000 due to their size.

When finding the overall cost of your extension, the use of your desired extension will also have an impact on its final price. You want to ensure a thorough idea of how much you wish to spend on your brand-new bathroom or kitchen is essential for those planning a new build project. 

Kitchens and bathrooms, on the other hand, are often trickier to budget compared to living rooms or bedrooms. The reason for this is the necessary plumbing you must consider, alongside the fittings and appliances it will need to function.

The cost of implementing your dream kitchen extension will begin at prices of around £10,000 for the cheapest designs. Plenty of the price will come from the quality of your chosen appliances and the materials used to curate them. A bathroom extension will ultimately increase the overall cost of your project by approximately £5,000, yet this will usually depend on the style of finish you're after.

There are numerous variables to consider when totting up the overall costs of your household-extending project, so it's often helpful to decipher how the budget will be split between each aspect and the professional costs involved.

For example, a good rule of thumb to go by is:

The average fees of London Architects will take up around 10%

The administration fees will take up 1%

Your structural engineer will often take 4%

Your surveyors will often receive 3%

Your contractors will take 30%

The materials will take up 20%

The fittings will take up around 5%

The effective structural glazing extensions take up 15%

Finally, the VAT will often sit around 20%

You can help extend an existing building separately and along the side of the rear without the need for planning permission, as this typically falls under 'Under Permitted Development.' 

However, you must beware that once your extension additions form L-shaped extension walls or join with other extensions to curate an accessible wraparound, you will require planning permission to complete your build. If big projects extend over the maximum height, you'll be asked by planning consultants or a local authority to alter or remove your progress.

Almost all existing wraparound extensions end up connecting to create an L-shape along the rear or side of your home, acting as a privacy design or party wall; therefore, you need planning permission as these do not fall under the permitted development rights and services. 

The Party Wall Act states that you require planning permission before implementing a wall onto your existing home that could overshadow or block your neighbour's view, limiting the value of their property and quality of living.

For extensions such as single-storey extensions, wraparounds or double-storey wraparounds, you must ensure that your architects consider the following factors:

The visual amenity of the location

Any overshadowing or loss of natural light

If the new build or extension has any effect on conservation areas, period properties or listed buildings

If your extension significantly impacts the overall appearance or character of the surrounding area.

Assessing the area scale and dominance of your extension

Consider any loss of privacy that the extension could create.

Finally, we recommend looking more closely at the materials, design and overall appearance.

When working with our architectural team at Trimble Architects Ltd for any planning or development you require, our staff pay particularly close attention to such matters, ensuring your planning applications include all the necessary and suitable components to guarantee your wraparound extension planning permission.

A whole host of research has been carried out by Nationwide that demonstrates how much home extensions of various kinds can add significant value to your property. 

The amount will depend on the type of extension you opt for. For example, adding a double bedroom or en-suite bathroom to your household can increase the overall value by approximately 23%, as many homeowners are tempted by having their private bathroom. 

To boost the value of your home by around 13%, we recommend adding a kitchen extension with square footage to your single-storey; many future buyers and tenants are persuaded by a much larger kitchen that promises more room for cooking, eating and chatting with guests.

Trimble Architects

Based in Twickenham

South West London

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If you require help and advice from our wrap around extension architects get in touch today. Trimble Architects are based in Twickenham and work across south-west London.

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