Are you sure it's Cedar? That looks awfully knotty and is the wrong shade of red.Now clad in cedar
Are you sure it's Cedar? That looks awfully knotty and is the wrong shade of red.Now clad in cedar
If that is an unventilated cavity between the insulation and the sheathing, then yes there could be problems.I'm worried I may have caused more of a problem than I solved by sealing everything
I know what you're saying, however having been sawing through it for the last few weeks I can confirm it really is. In fact you can still smell it from the next street. It is knotty, but I couldn't afford the Canadian stuff, as attractive as it is. This is Western Red Cedar grown in the UK. It's knottier than the Canadian version, but it's much lighter than Larchwood and just as resinous as other Cedar so has all the qualities. Shame about the knots, but then it was about £650 for 25m2, so less than half the price.Are you sure it's Cedar? That looks awfully knotty and is the wrong shade of red.
OK, that makes sense, thanks for your input. The room hasn't been used yet or lived in in anyway, so all the moisture present must have been from the plastering and also screeding, although alarmingly that was a few months ago and there are still huge beads of water trapped in there. I could have put insulation behind my sealed containers, but didn't think about it. These were otherwise going to be gaping holes sucking air out into the roof and wall cavities, so my main motivation was just to prevent the air from moving out into those spaces. I might just leave the doors open and run a fan heater or something for a few days for it to dry out. Worried about future use though..The problem is there's no insulation behind the backbox so the back of it is freezing cold and a massive thermal bridge.
There will be a minimum amount of insulation needed to prevent it getting too cold.
It is better to trap the condensation in the box then let it form further into the structure though.
If the room has just been plastered them there would be a lot more humidity, so it would be less bad if it's kept dry and well ventilated in future.
Yes, reading the tech guidance from Kingspan I understood that cavity was to remain sealed as it forms a closed cell of insulation with the PIR. The studs are 90 - 100mm, so as the PIR is 70mm, and the remaining 20-30mm is supposed to be unventilated I thought. Then there's OSB on the outside, membrane, battens and then ventilated cladding. The air from the internal space isn't supposed to leak into the framework. I could have got it all wrong though!If that is an unventilated cavity between the insulation and the sheathing, then yes there could be problems.
There is already air in there (it's not a vacuum), and despite anyones best efforts there is always some air leakage - that's why cavities like this should be vented. But what you should have done is not had a cavity at all and put the insulation tight up against the sheathing.The air from the internal space isn't supposed to leak into the framework. I could have got it all wrong though!
But have you formed a ventilated cavity?I just watched a quick video from Kingspan:
..and it does say that if you install the PIR boards flush with the inside wall just behind the plasterboard, as I have, that you should fit battens behind it as 'stops' to prevent it moving into the cavity at the back of the studs. That's the way I did mine. Obviously what's great in theory doesn't entirely work out in practice, but I'll just have to live with what I've got and hope the little air leaks and breaches don't become catastrophic. I'm working on the assumption that all the water I'm seeing collected in all my sealed service voids is just from the plaster as it dried back in October. It's had nowhere to go. It's alarming to see but a good airing out is long overdue, and maybe some heat.
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