Extension - what do you wish you’d done??

[Helladelinquent]

We are FINALLY getting round to doing an extension on our house. We’re at the planning drawings stage and the engineer seems determined to take away all our wall space! He’s putting in big windows and widening doorways. We want wall space for bookcases and display cabinets.
(we have a meeting with him later to discuss).

In the meantime - any advice on things you did/didnt do that you wish you had??

I wish we had thought more about heating and we should have put underfloor in but it was a cost too far at the time. Also lighting, we never use our central lights however I do wish we had put one in the extension. We have bifold doors which are the width of the extension and are fab as when open the whole space works.

We’re doing underfloor heating in the extension and retrofitting the existing house.
We haven’t thought too much about lighting though so something to think about.