I have planning permission for a single storey extension to the rear of my house, opening up the existing lounge / kitchen into the new extension. I have architect & structural drawings complete.

I’ve involved 4 local building companies, who gave me an estimate price based on the architectural drawings, 3 of which were within £5k of one another. This was in March. Based on those being within my budget, I decided to proceed.

I now have the planning and full drawing package. I’ve asked them each for a quote.

Here’s my dilemmas. Firstly is it normal for a builder to ask you to pay for a quotation, namely £300 to cover the QS costs and second, the huge variation between quotes £40k, compared to estimates £5k. This is just 2 months later and with basically the same drawings.

I know you can’t make the decision for me but I’d appreciate any feedback on the request to pay for the QS and the substantial variation in cost.

Thanks in advance.