Hi all, I was considering using Thermalite type 3N Trench blocks 300x450x215 for below ground ( small single storey ext.) but they look quite soft and easily chippable I wondered are the strong enough in damp foundations??
anyone experienced using them? Are they ok because they would save valuable time in getting out of the ground.
anyone experienced using them? Are they ok because they would save valuable time in getting out of the ground.