Hi, A little background info first- my house is an 1870's double front cottage with two 70's additions at rear. The former owners in their infinite wisdom decided not to take down the yard level when laying terracotta pavers over sand, so pavers were raised to the level above sub-floor vents. Unfortunately the paving was so smooth that rain ran in a sheet to the vents and went straight in! I am laying an 8 square metre slab (10cm), to be under 10cm sandstone paving, the slab being...

More...