Using the Calculator
With our calculator you can input your desired size in metres, type of extension or conversion, number of storeys and then location. The calculator will estimate the total value of the extension or loft conversion based on the regional price per square metre and expected uplift each type of extension will add.
Single & Double Storey Extensions
When inputting the extension size remember to use external dimensions, the calculator automatically calculates the correct floor area taking the wall thickness into account.
Loft Conversions
When using the calculator for a loft conversion it’s important to enter the dimensions of the useable floor space. This is the total loft floor area minus the space for the stairwell and any floor space where the height from floor to eaves is less than 1.2 metres, this will give you the total usable loft space used for the valuation.
Our extension cost calculator and loft conversion cost calculator can be used first to determine the expected build price, once you have this plus the value added figure from above you can then calculate your return below.
Return on Investment
Enter the calculated figures below to determine your return on investment for the build. A good ROI would be in the region of 70%, but can vary greatly.
How much value can a single storey extension add to my home?
A single storey extension can add approximately 5-10% to your property’s value. This increase depends on factors such as the extension’s size, quality, and how it enhances the existing living space. For example an open plan kitchen diner can be more desirable than a simple addition of a study or playroom.
What is the potential value addition from a double storey extension?
A double storey extension may add around 10-20% to your home’s value. This is because it often increases both living areas and the number of bedrooms or bathrooms, which are attractive features to potential buyers.
Do loft conversions significantly increase property value?
Yes, loft conversions are highly effective in adding value, potentially increasing your property’s worth by up to 20% on a typical 3 bedroom house, especially in built-up areas. They are popular due to their affordability and the additional living space they create without expanding the property’s footprint.
How does the quality of an extension affect my home’s value?
The quality of construction and finish is crucial. A well built extension with high end internal and external finishes can enhance your property’s value. Conversely, a poorly built extension may decrease the value and deter potential buyers.
Are there other factors that influence the value added by an extension?
Yes, factors such as the property’s location, the type of extension, and its integration with the existing structure play significant roles. Consulting with local estate agents and your architect can provide information into how an extension might impact your home’s resale value.
Is it more cost-effective to build an extension or move to a larger home?
Building an extension can be more economical than moving, especially when considering costs like legal fees, stamp duty, and moving expenses. Additionally, extensions allow you to customize your current home to better suit your needs, potentially adding significant value.
Sources
https://www.gov.uk/guidance/about-the-price-paid-data
https://epc.opendatacommunities.org/