House Extensions

Costs and Problems with House Extensions

Q -The foundations of our extension are underway but we have a problem with the contractor. He says that he is having to fix timber boarding in the trenches to support the sides because soil is so loose and he ants paying extra for this work. Is this our responsibility and, if we have to pay extra, what should it cost?

A - Supporting the sides of trenches is normally a risk that is assessed by a groundworks contractor when preparing his quote. Your contractor must have inspected the site before he quoted you so he should have included the cost of this work then. But you may think it is worthwhile to pay a nominal sum in case he leaves the site.

There are two kinds of earth support, close boarded and open boarded (it used to be called planking and strutting). Close boarding is used where the trench sides are not able to support themselves, such as in sand. Open boarding is used where it just loose earth and requires intermittent support. In clay, the sides of the trench would be self-supporting and would not need boarding. Close boarding costs about £10 per square metre and £5 for open boarding.

House Extension Quotations

Q - We have received two quotations for a large extension from to our house and we need to examine them in detail and negotiate a firm price with one of them. Unfortunately, neither of us have any experience in the construction industry. We have been advised to employ a quantity surveyor to do this for us and wonder what this service would cost us?

A - The fee scales recommended by the Royal Institution of Chartered Surveyors for ‘...negotiating and agreeing prices with a contractor...' are £750 plus 0.3% for the balance of work over £150,000 but these fees are recommended not mandatory so it may be worth shopping around.

Q - I live with my parents in an end-terrace house with a single attached garage. I would like to rebuild the garage and turn it into a one-bedroom flat for myself on two floors with a bedroom with en-suite bathroom on the first floor and a small living room/kitchen on the ground floor. Could you give me any advice on the feasibility and cost of this idea?

A - Assuming that you intend to demolish the garage and build a two storey self-contained extension it should cost between £25,000 to carry out this work including a small sum for paving and drain connections. The first step is have a talk with your local planning office. Make a sketch of what you would like to do and get their informal reaction.

Building Extension Problems

Q - We have accepted a quotation from a builder for a large extension to our house. This firm has carried out a lot of work in this area and has a good reputation for fair prices and good workmanship. Unfortunately, he is also is also renowned for going missing for a couple of days and not completing the work on time. He has assured us that this won't happen in our case but is there any way we make sure of this?

A - On large building contracts, a system of liquidated damages is enforced where the contractor is liable to pay weekly damages for delays that he has caused. But the damages must represent the assessed losses suffered by the client and not be a penalty.

If the completion date is important to you, and if you can afford it, you should consider offering a bonus for completing on time. Also let the builder know that you are keeping a diary of the project so that he knows that slipping off to do other work will be noted. Finally, make sure that you don't overpay him, particularly in the early stages of the job, because an overpayment can lead to a lack of commitment.

Contractor prices for Extensions

Q - We live in a fairly remote cottage and there are very few builders in the area. We would like to build an extension but are concerned that cost of contractors travelling from the nearest town (thirty miles away) will make the cost prohibitive. Any suggestions?

A - You are probably worrying unduly. The travelling time involved is only three quarters of an hour each way so it will probably only add a few hundred pounds to the overall cost of the work.


If you found this page useful please click the +1 button below to tell Google that its a great page!

Please share this page with others, and leave a comment, we value all feedback!

Was this page useful? Do you have something to add? Do you disagree?

If your comments meet our guidelines then we will publish them (you do not need to register!)

Ttradesman - click here to join our network to receive leads from customers in your area