• Naomi CB

To Extend or Not to Extend...?

If you are looking to upscale your home, but are not too keen on the idea of moving, a house extension may be your answer. With 41% of homeowners who would rather choose to extend rather than move house (according to TSB Bank’s research on homeowners), carrying out building works to create an extension has become a popular alternative, even if this may mean remortgaging. Most houses in London have an imbalance of spaces between living and sleeping; there are many bedrooms for only small amounts of social spaces. Rebalancing this is often done through extending the kitchen outwards, towards the rear of the property. Many Victorian homes have an ‘outrigger’ (L-Shaped extension) that creates a ‘dead’ space to the rear of the property, originally design for light to enter the main house. This is now an ideal space in which to extend and current glazing technology allows high levels of light to be maintained. Sometimes you may also need more bedrooms or home offices (especially with the pandemic).

As well as upsizing, you probably will have some ideas as to what you want your new space to achieve, and there will be many design options available for you to successfully realize your vision. A house extension will almost always increase the value of your property, sometimes up to 30%, so it is definitely something we encourage homeowners to consider.

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Getting Started

Before you appoint an architect or designer, here are a few things that we recommend you do on your own. The more thorough you are, the more likely you are to successfully achieve what you are looking for, both in terms of personal comfort and in terms of budget.

1. I think I want to extend, but I’m not sure…The main deciding factors for homeowners who opt to extend rather than moving include a sentimental attachment to their current home, the cost of moving for additional space being greater than the cost of extending, or finally the neighbourhoods and communities being nice. If these ring a bell, it might be worth doing some research on home extensions…!

Although extending your home will often be less expensive than moving, this will ultimately depend on the size of the extension, as well as the finishes and quality you expect from it. Start by making an in-depth study of possible moving costs, so that you can eventually compare these costs to those of a house extension. Finally, look at other extended homes in your area to understand the possible value an extension may add to your home. You should do this whether or not you eventually intend to sell as it will provide a balanced perspective. You may need to invest more than the extension is worth, but perhaps this is worth it if you intend living there for the foreseeable future.

2. What kind of extension do I want?; this may seem obvious, but the clearer the idea in your head, the more time and cost you will save during the process. Are you imagining separate dining and utility spaces, or do you prefer a more open-plan design? Perhaps you want more room for food preparation, but do not want this to be at the expense of the atmosphere in the living room. Our advice: think carefully about what you would like to achieve with your extension for the most effective results. Little things can have a big impact and save time! It is important to give a clear brief when you engage a designer or architect to propose an extension to your home, but remember to allow them some freedom in design. Stay open minded to their creative and professional approach.

Here are a few types of house extensions and their advantages to help you decide.


a. Single Storey and Kitchen Extension: for a little extra living space – ideal if you have a growing family. They can often cater to a greater variety of budgets, depending on size and finishes, and has the possibility of adding up to 10% value to your property.

b. Loft Conversion: the more popular option – it is usually less disruptive in terms of building work than a ground-level extension, which is perhaps more attractive if you plan to be living-in during building works. In terms of planning permission, loft extensions are often considered less invasive, especially if designed on the rear of your property, and therefore are more likely to have a smaller lead time towards completion. Plus, a good-quality loft extension could increase the value of your home by 12.5%.

c. Two Storey Conversions: These are usually more expensive given the deeper set of foundations, as well as the more probable need to apply for Planning Permission. However, they will add the greatest amount of surface area to your property, thereby increasing the value of your home in a more cost-effective manner than single-storey extensions, if designed properly. They hold the opportunity to provide an integrated kitchen-living room, as well as an extra bedroom within the same footprint, so definitely and option worth considering.

3. How big does it need to be? Size will greatly affect the cost of the project. You may imagine your extension to be only a kitchen, but perhaps with the space and budget you have, you might be able to fit in more without increasing the size. Or perhaps you want to keep it small, but you are unsure as to whether your envisioned project will fit. Determining the right size will set you on the right path for a successful project completion. To help you decide on the proportion of your house extension, have a look at our blog on your Permitted Development rights as a homeowner here.. Anything beyond this guidance will require planning permission.

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4. Don’t Forget the VAT! One of the most important things to know, is that most builders and architects often talk excluding VAT. Remember that VAT is 20%, depending on potential exclusions, and so be mindful to mention that your budget includes or excludes the VAT.

5. Have a little extra! Finally, it is possible that some issues will arise during the construction process that may require additional costs. Most extension projects in London are old Victorian buildings so don’t be surprised if you discover that something needs fixing! Since this might be the case, make sure you have a little extra saved up ‘just in case’. The industry standard is recommended between 10-15% of the construction budget (+VAT).

6. When do you need it finished? You might need the extra space to be ready for a certain time, and otherwise, it might prove difficult to adapt your life to the building works being carried out in your home. Consider the implications of this, and consult with an architect or designer to confirm whether your timeframe/expectations are realistic. Most rear extension take 10-14 weeks in construction. Loft extensions vary between 8-16 weeks depending on their complexity and whether clients are living in. We always recommend leaving a little bit of margin time to avoid unpleasant surprises, both before expected construction commencement and expected finish time. Problems can always arise regarding neighbours, suppliers or even pandemics! We recommend proper planning and getting any party wall negotiations underway as soon as possible. Allow 6 months to 1 year prior to construction starting to give you time to get the design you want, planning permission and finding the right builder for you.


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