EXTENSION COSTS PART 1: SINGLE STOREY
In the first of our mini-series on extension costs, the Build It Estimating Service’s Adrian Wild sets out indicative costs for single storey additions
Get an idea of what you can expect to pay for your project with indicative prices from the Build It Estimating Service
Extending is a fantastic way to add space and make your home work more effectively for you. But as with any major project, one of the key questions you’re likely to ask is what it will cost: and this miniseries aims to give you a starting point for your scheme.
Developed by the Build It Estimating Service, the indicative costs given in this first instalment are based on a singlestorey addition suitable for a kitchen, with a gross internal floor area (GIA) of 25m2. Prices include all the infrastructure (including cooker and socket circuits, hot and cold water supply, and extension of the heating system).
An internal door has been included, but a wide structural opening from the main property would be an additional cost – as would internal walls, flooring and the kitchen fit-out (all of which can vary significantly depending on specification).
Our standard specification is based on a brick and block extension with PVCU windows and standard patio doors. The flat roof would be in torch-on felt, while pitched versions are based on concrete tile. The optimised spec demonstrates what you might expect to pay for upgrading the project. It’s based on stone and block construction, aluminium windows and bifold doors. The optimised flat roof option features a roof lantern and GRP roofing, while the pitched designs include a vaulted ceiling, rooflights and clay plain tile finish.
These prices take in the builder’s overheads and profit, as well as VAT. If you did the work DIY, you might save as much as 50% on total costs; but at the expense of your own time and the risk of missteps along the way. Potential additional costs include architect’s plans (if you’re taking this route), clearing the site and moving services (such as drainage).