Cutting into sips walls...

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charliegolf

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Hi all,

I have built a sips garden room from a kit- all good. For the electrics (4 sockets and lights), I have considered flush mounting all the fittings using drywall pattresses. This means cutting the inner wall and scooping out the insulation to the depth of the box. I'm confident the building won't fall down due to a few small holes being introduced. But should I worry about cold spots and possible condensation leading to dampness?

It would be nice to have them flush.

PS, I am not dry lining: the finished wall is staying as OSB. Thanks
 
Don’t blindly follow this advice but I watched a programme about sips.

The way that they routed cables was to heat large ball bearings to red hot (in tongs) and drop the ball onto the polystyrene.
Obviously check there are no noggin like obstructions.
The ball drops using gravity right through the poly.

You’d need to do this on install if doing horizontals, but it can be done on built sips by correct positioning and fitting a chute to catch the ball when it drops.
 
You'll get condensation inside the back boxes, as they will be inset into the condensation so will be the coldest points in the room. Rusting and/or electrical issues will follow.

Get some nice industrial fittings and ducting, it looks great if done neatly with all the proper fittings.
 
Ivor Windybottom said:
You'll get condensation inside the back boxes, as they will be inset into the condensation so will be the coldest points in the room. Rusting and/or electrical issues will follow.

Get some nice industrial fittings and ducting, it looks great if done neatly with all the proper fittings.
Click to expand...
Doubtful, the insulation behind the boxes will still be 100m thick or thereabouts.
 
freddiemercurystwin said:
Not sure he's thought that far ahead ....
Click to expand...
Oh but he has... Cables outside the sip in conduit, but inside the cladding. Penetrating behind each fitting, and going back out again to route to the next. On reflection since asking, fittings will be surface mounted slimline back boxes. Leave the sip alone. (apart from cable holes) A pro is doing the job, by the way; and was ok with my first idea of drywall boxes, but I think we'll play safe on the condensation front.
 
You'll definitely get condensation within the trunking if you're going to/from the outside of the insulation all over the place. The cables will be freezing cold in winter, so will make all the metal contacts as cold as the outside air. Everything will be dripping wet in no time. I doubt you'll have a seal in the backs of the boxes, so the air will be as cold too, possibly with draughts blowing through any gaps.

Keep it simple! Putting any holes through insulation is likely to result in condensation, damp and rot issues. For the same reasons I wouldn't put recessed lights in anywhere that's an external facing ceiling, e.g. a top floor, bungalow or flat roof. Many do, but I wouldn't.
 
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