JackCD

Yes I believe they will have to, to accommodate the block space.

Yep exactly. The critical error is the drop in the wall. They simply needed to follow the course of blocks form the utility all the way around. The only thing I would accept as a resolution has now been agreed. They are going to lift the frame up, build the course of blocks with damp on top and then set the frame back on top. How it should have been done from the start.

This is nothing to do with vertical DPC. It's the base DPC below the wall plate that has been installed too low. Basically for some incase reason they dropped the wall when they got to the garage instead of running the same course of blocks through to keep the 150mm+ to DPC. In terms of a shed Yeah I tried to convince my mum to have a proper brick/block extension but unfortunately it fell on deaf ears. Update: Building work paused, building inspector will be checking and I will make the issue clear.

Thanks a lot for the info guys. It confirmed my suspicions, I knew the DPC height was a massive failure as soon as I saw it. If she chooses to continue I hope the building inspector has them correct the DPC but the state of some new builds these days I don't have much faith. Once the ground is levelled off it will be under in some places. Even if they still believed the old law of having the floor drop it makes 0 sense that they choose to drop the wall also. They should have carried the DPC of the utility (matches the house - 150mm clearance) all the way around. Another thing I noticed is the left over blocks you see in the photos would cover the wall they dropped so it appears to have been calculated to go all the way around.

Hello all, My mum is having a timber framed extension built on to her house (side extension). The extension has a utility room at the back and garage at the front. The damp course around the utility matches the house as you would expect. However, the garage wall drops down 150mm where the damp course is barely 10mm above ground. The builders said a garage floor has to be 150mm lower than the house which turns out to be correct (some fire regulation). While the floor has to be lower I don't see why the wall should be lower. In my view it should match the height of the extension with only the floor dropping. The builders have accepted that the damp course is low and said they would put in drains. ----- I would love to hear your opinion on this. My view is either 2 things should happen: 1. Pause construction and have the plains changed to a habitable room instead of a garage (my mum does not intend to use the garage as a garage, only storage). 2. The walls of the garage should match the wall of the utility so damp course follows through. This will not effect the concrete floor which will remain 150mm lower as the utility will be insulated and screeded. I have attached some photos and would love to hear your opinions. Many thanks.