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Cost of 2 Storey House Extension

Why build a two storey extension

Many people find that they outgrow their property as their commitments and family size changes and that they need further bedrooms or an office and are worried by the costs involved in moving to a larger property. It can therefore be a more sensible option to build an extension as long as you have the extra land available. Building an extension of any sort can be a hassle as you may be unable to use your garden or driveway while building work takes place.

How much will it cost?

On average building a single storey extension will cost roughly around £1000 per square metre with a two storey one costing the same plus approximately 20 per cent. The increase in cost for two storeys is down to several reasons, the main one being that the building of a second floor is more labour intensive as the single floor can be built without scaffolding. Other extra costs to be taken into account include the use of extra concrete as the foundations for a double storey need to be stronger and deeper than a single one, the extra materials needed i.e. plumbing, insulation and windows and the extra roofing costs incurred with tying into the original roof. There are also costs involved with hiring an architect to draw the plans and with applying to the local council for planning permission and building regulations should they be needed, with the building fees being the largest. Planning costs will vary with the size of the extension requested and a completion certificate should always be obtained from the building inspector once the work is finished. This will be needed if you decide to sell the property at any time. It will also need to be remembered that plans can change once the work has commenced as extra work below ground can sometimes be required and this can add to the quoted cost as most builders only quote for what they can see.

How to keep costs down

Keeping costs of an extension down can be done if you are prepared to do some or most of the work yourself. Project managing, labouring and waste removal can all be done fairly easily to help reduce costs. It can also be helpful to source the materials needed yourself and just pay the builder to build and fit them. It is certainly worth getting a quote from the builder for both though.