This is perhaps the most commonly asked question when clients start thinking about a home extension or internal reconfiguration project.
It’s also the toughest question to answer, as there are so many variables …and every property and client brief is different. Even builders, who provide project quotes as per of their job, struggle to provide estimates for the same reasons.
But obviously, (unless you have a money tree growing in your back garden!), it is important to consider budget and end value throughout your project. Especially when making design decisions and to help manage expectations.
We find that calculating the size of your extension using a rough price per square meter can be a good starting point. In Yorkshire, this typically ranges from £1500 - £1800 per sqm (with a second storey around £1000-1250 per sqm). This ‘build cost’ usually covers the cost of construction - standard foundations, external walls, standard windows / doors, internal walls, floors and ceilings, steelwork, plastering, basic heating, plumbing and electrics. You then need to allow for VAT, any demolition, upgrades to more interesting windows and doors, kitchens, bathrooms, underfloor heating, feature light fittings, floor finishes, tiling, etc. And around 6-12% for all your professional fees (Architect, Planning, Building Regs, Structural Engineer.)
I recently came across this article, which I found simple and informative. (The internet can be a wondrous thing at times!) Here’s the link:
https://designfor-me.com/cost-planning/how-much-does-a-house-extension-cost/