Waste pipe in wall cavity

macgabhs

New build underway waste pipe from upstairs ensuite was to be routed internally to avoid a drain pipe on the front elevation of the building. Architect is suggesting placing the pipe within the wall cavity between the inner and outer leaf of the external wall. It's a 200mm cavity to be fully filled with beaded insulation. This just sounds wrong to me for numerous reasons not least the fact that it will be completely inaccessible should anything happen but I'd be worried about the potential for condensation within the cavity. Architect is saying the cavity is large enough so that there would be no thermal bridge. Has anybody heard of this approach before?

Gumbo

Wouldn't be mad about the idea myself, even if,it could be designed to comply. I'd rather have it internally and boxed out.

Metric Tensor

Wouldn't be for me either OP. Future access problems alone would be enough to stop it. Not to mind question marks over venting, etc.

The best way to do sewer pipe drops is to come out through the wall and down the outside (vented upwards) with the sink and shower into a hopper alongside for venting/smell redundancy. In the days of the Celtic Tiger aesthetics seem to have taken over from good design and in many cases there is needless complication and future problems brought about by trying to "hide" such things.

Now having said that if this is the front of your house I see a definite reason not to have the pipe outside - even if it's the best solution you have to bow to aesthetics sometimes! As kceire says box it off inside the wall. That way if there's problems in future at least you have some level of access. Bear in mind the venting may be difficult and there is less than ideal shower/sink connection detail also forced upon you.

Gumbo

Metric Tensor wrote: »

Wouldn't be for me either OP. Future access problems alone would be enough to stop it. Not to mind question marks over venting, etc.

The best way to do sewer pipe drops is to come out through the wall and down the outside (vented upwards) with the sink and shower into a hopper alongside for venting/smell redundancy. In the days of the Celtic Tiger aesthetics seem to have taken over from good design and in many cases there is needless complication and future problems brought about by trying to "hide" such things.

Now having said that if this is the front of your house I see a definite reason not to have the pipe outside - even if it's the best solution you have to bow to aesthetics sometimes! As kceire says box it off inside the wall. That way if there's problems in future at least you have some level of access. Bear in mind the venting may be difficult and there is less than ideal shower/sink connection detail also forced upon you.

I've seen down pipes painted with extreme care to match in with brick and mortar coursing so also. Might be worth exploring.

Poor Uncle Tom

Why not hide it in plain view, embrace design features......

I have an example picture but I can't embed it...

Curious Geroge

Where's the problem ? Where the sewer pipe is in the cavity, it is vented through the roof. Once in the cavity and the build completed, the sewer pipe in the cavity could'nt be more protected, what could possibly happen it that would cause damage to it?

gctest50

Curious Geroge wrote: »

........what could possibly happen it that would cause damage to it?

these lads, they'd think they're at a water park, then get bored and eat their way out through the pipe :

mel o

O how I wish I didn't press play. With my volume turned up. Urgh

mel o

O how I wish I didn't press play. With my volume turned up. Urgh

mel o

O how I wish I didn't press play. With my volume turned up. Urgh

gctest50

mel o wrote: »

O how I wish I didn't press play. With my volume turned up. Urgh

then they'll never leave :