Expert: Bruce E. Johnson - 11/10/2008

Question
Hi, We have an 1870's double brick with two 70's rear additions that we are planning to put a patio to.

The former owners had installed paving over sand that came up flush with subfloor vent holes and water ran straight in when it rained, so I ripped it all out to put in a patio.

We have a lipped brick row at the wall footing/foundation and I have two rows of brick height before I hit dampcourse and ventholes.  I would like to put down a slab with thick sandstone over the top (approx 8 square metres) and would like to know how the slab should meet or stand off from the wall as the foundation bricks jut out and would not like any settling to upset the wall regardless of the smallish slab size.

Any advice regarding laying the slab next to this would be appreciated.

Answer
Hi garth, if I am understanding you correctly  you should put an expansion joint between the slab and the house brick.  This is a 13mm or 1/2" thick by 4" high material made for this purpose.  It is installed against the brick and then the slab is poured up to it.  This expansion material allows for movement between the two different materials.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com