Hi
I'm laying some slabs up against the wall of my house and the top of them will end up only one brick course below the DPC.
I always understood it should be 2 courses below - but reading some stuff on this NG it seems DPC's aren't all they are cracked up to be. Is one course going to be OK or should I put a piece of DPM under the slab and up the wall?
Dave
reason is that it is reckoned rain drops can rebound to about 6ins (150m)- ie around 2 courses of bricks, so wet/damp bricks remain below the dpc.
That is also part of the reason why blue brick dpcs are 2 courses thick.
but reading some stuff on
that's right, if laid poorly or without due regard to masonry & other absorbent building materials bypassing them; not so, if care is taken. Also beware of subsoil being under water pressure, which will find any weakness in dpc defences.
Is one course
might be, especially on sheltered side of building.
or should I put a piece of DPM under the slab and up the
unless that is fully sealed into the building dpc, it could very well make matters worse.
reason is that the underside of your dpc will be damp under the slabs and almost certainly the damp will be sucked up the dpc upstand against the wall by various processes like wicking and capillary action. Your bricks under the dpc would then be permanently damp.
IMHO you'd do best to see if you can place the slabs lower, slope them away from the wall, or improve shelter against rain falling vertically.
If your dpc is blue bricks, then IMHO you're less likely to have problems, the gap then only helps keep the mortar courses of the blues dry.
HTH
Hi
I'm laying some slabs up against the wall of my house and the top of them will end up only one brick course below the DPC.
I always understood it should be 2 courses below - but reading some stuff on this NG it seems DPC's aren't all they are cracked up to be. Is one course going to be OK or should I put a piece of DPM under the slab and up the wall?
Dave
The solution I have heard to this problem is to lay fine gravel between the slabs and the wall, perhaps a 6" strip. The reasoning is that raindrops can splash
6" high when hitting a hard surface, but have some of their energy take from them when hitting gravel and thus don't splash so high.Andy
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