Double Storey Side Extension and Single Storey Rear Extension

newnhambolton

The double storey side extension consists of the following:- on the ground floor , a garage, study and cloakroom. On the first floor, a bedroom and a shower room. The footprint measures 8.75m x 2.5m.

The rear single story extension consists of a kitchen/breakfast room and utility room measuring 8.35m x 4.2m in total.

I have asked all the builders to quote to build a shell up to plastering, including electrics and plumbing. So no decorating, tiling, kitchen fitting, etc.

The quotes have come in as £63K, £90K and £110K. My budget is only £70K.

Is the £63K quote a reasonable one for a project of this size? Do you think he may have underestimated? Or do you think my budget is unrealistic? I am based in Bristol.

sujman

For shell builds, I have previously used £1,800 per square metre (footprint) for a double and £1,100 for a single (ex VAT).

Using these numbers, the cost of you extension should amount to around £78,000.

Perhaps then £63k is a decent quote.

newnhambolton

The 63K quote included VAT!! I don't want to discover half way through the project that he has massively underestimated.

sujman

Perhaps say to him you are very interested in his quote and that to double check he is building to your required spec, ask for a detailed breakdown of the costs.

If he still comes back with the same number, you could be honest and say the quote looks "a little cheaper than expected", can he explain how he can save money where others can't?

Obviously, you dont want to pay more just for the sake of it but as you said, you dont want to be caught out short later down the line.

Another key check is to view examples of his other recent work and be cheeky enough to ask the other customers how much they paid and see if it stacks up.

Worst case, the builder is quoting cheap to secure the job, get some money (deposit etc) and abandone the job or "blackmail" you into paying more later, in order to complete the job.

I looked up an old quote I had done last year for a rather large extension (therefore scale plays a part and reduces the average cost per sq mt) but the "finished" cost of the extension (which included kitchen, bathroom, tiling etc etc) averaged:

£2,100 for the double and £1,250 for single, inclding VAT.

On these numbers, your finished cost should amount to just under £90,000.

Therefore your overall budget of £70,000 may be ambitious but possible, especiall if £63k quote is correct.

newnhambolton

So, is the 90K for the finished product? The 63K the builder is quoting is for a shell, including plastering, plumbing and electrics but no finishes.

We are doing the kitchen, tiling, painting, supplying our own sanitary ware, shower, shower door, shower tray and even the radiators and TRVs.

sujman

Yes, £90k for the finished product. But, I had a quote for a 54m2 double storey (versus your 22m2) so some fixed costs are shared over a lager area and therefore my cost per m2 is lower.