ian cooper
hi, basically you will have to dig deeper for the foundation if you don't want to use piles. different species of trees require different depths depending how close to the new build they are. you say you have conifer trees, if they are leylandii at 4m away you will need a foundation depth of about 2.5m from ground level, then a 50mm compressible material (claymaster) on the inside face of the trench and mass fill with concrete, the new floor should then be suspended onto this foundation, even cutting the trees down will not solve the issue. hope this helps. ian.
