Cost of an extension
Before contemplating the costs of a house extension, it's worth considering how much it would cost to move to a larger home if your decision to build an extension is based on running short of room.
While an extension is inevitably a sizeable investment, the costs compared to moving are likely to be quite favourable. When you consider the costs of moving in terms of stamp duty, estate agents, legal fees, removal costs and sundry expenses the decision to stay put and build an extension might be the most cost-effective option.
Working out costs
The first thing to stress is to make sure you know exactly what is being quoted for. If you ask a builder like ourselves to provide costings for your extension, be clear on what is and isn't being quoted for.
A rough and ready guide is to take a base figure of £1,200 - £1,600* per square metre and multiply it based on the size of structure. If it would go to two or more storeys, then you'd use half the above figure to factor these in as the ground floor work would have to be done irrespective of whether extra storeys are being built.
This rough calculation would provide a guide price for an extension with basic plumbing and electrics, but wouldn't include items such as a fitted bathroom or tiling.
* This figure is very approximate and may need to be double checked in the light of increased costs.
Design and architects
You'll need a design professional such as an architect to provide a proper blueprint for your extension. They should provide one or two variations on the plan to take into account possible planning objections, and it gives your builder a proper basis to provide an accurate and inclusive quotation.
You may need the services of specialists such as engineers and structural experts. For example, if special work is required to prepare the ground for building or underpinning then consultation may be needed.
Your architect or your builder can advise on what expertise you may require.
There will be costs to submit plans and obtain building regulations approval.
Some factors can be neglected but can affect costs significantly. For example, even moving a gas meter might cost several hundred pounds or more and it may turn out to be be more involved - and therefore more expensive - to connect to the drainage system.
If you're looking for a specific finish to match the rest of your property this can add to costs. Matching an extension to even a relatively modern house could add more expense such as locating bricks of the right shade.
Covering all eventualities
Your architect and builder should, between them, be able to appraise you fully of the costs involved. As experts in their fields, they'll be able to spot things you might not be aware of and advise accordingly.
That's why it's very important to engage an architect and building company with a demonstrable track record of providing a high standard of service. Using locally-based professionals is a sensible option as they'll understand local conditions and will likely have had many dealings with local planning authorities.
As respected builders who have built extensions of various types in the Portsmouth area, we'd be only too pleased to advise on your extension aims and provide a full, no-obligation quotation to help your decision making.
Call for help now on 023 9383 8191.