Having a builder on board is great – they are sometimes hard to come by!

But you should use people for jobs that are appropriate to the skills that they have. A builder is usually great at building things, but is unlikely to produce accurate and detailed layouts and schedules, which will make it very difficult for you to know what you are going to get and agree exactly what work will be done. If you leave it to your builder then they will be deciding your construction materials and methods, the performance of the fabric, the heights of windows, the details of the eaves, the number of sockets in each room….

This often ends in misunderstandings and a long list of additional extras that weren’t discussed at the start but are essential to your satisfaction with the project. These extras will end up costing you more as the project progresses.