MartB

Thanks Jules. Your advice is much appreciated! Martin

I live in Milton Keynes (Loughton). Also, I just had a look at my messages with the builder and this was his assessment: "there is no desiccation, no roots visible below 500mm from the removed tree; the moist clay that we have uncovered is low to medium shrinkage". Builder's assessment was that under these conditions, heave will not be an issue. I have also attached a picture of the trench showing the clay soil (if that helps).

Hello, I had to remove a hawthorne tree (7m tall) when building our extension. The (now removed) tree was 0.5-1m away from the new foundations of the extension. We have clay soil, and I am worried that heave may occur. I am thinking about laying a patio over the area where the tree used to be and direct any rainwater away with an ACO drain. Would this help against possible heave? The details: I cut the hawthorne tree down to 1m above ground level in Sep 2020. I also cut down two smaller trees (3m tall) growing right next to the fence. The soil is clay, and the effect was that during heavy rainfall, the water was standing on the lawn in this area (which did not happen before removal of the trees). Construction works began in early April 2021. The position of the hawthorne tree is 0.5-1 m away from the foundations of the extension. Foundations are 1.5m deep (trenchfill). The area between the new extension and the garden fence, where the trees used to be, is about 2.5-2m wide. My thinking is to lay a patio there and direct any rainwater away from this area with an ACO drain. The thinking is that if the clay soil cannot get wet, it cannot swell (?). Even if this thinking is correct, I do wonder if this could potentially cause subsidence issues due to the clay soil drying out. Any advice would be much appreciated. Many thanks. Martin