Mouldy walls

Fern Bench

Hi

I'm finding cold, damp patches on the walls of child's bedroom. Mould is starting to accumulate there. I've cleaned it off so it doesn't really show in the pics, but I want to show the affected areas. It's the area where the top of the bedroom wall curves to meet the slope of the roof, (it's 1 1/2 storey)

I reckon this must be because there is a weak spot of insulation in the attic all along this curve. The corresponding area is affected in all upstairs rooms. The rest of the room is fine.

I looked at the insulation in the attic that was put into these areas and to my untrained eye it looks like there is not enough rockwool between the joists. The rolls are only 2/3 of the with of the joists and in Some spots I can actually see around the rockwool and down towards the plate. I know that you're not supposed to pack it in more densely as this reduces insulation, but if I pulled out all the old stuff and cut a new roll to the proper width do you think this would help?

Is there anything that says I shouldn't interfere with it as it allows for air flow etc? I also noticed last year that the attic was damp, some of the joists actually felt wet to the touch during the coldest months.

10-10-20

Yes, that's poorly done alright. Really the insulation needs to run in a consistent and uniform manner from the sloped ceiling into the attic, covering over that wooden plank too, but leaving a 50mm gap between the insulation and the white airtight membrane. You can get a rafter vent tray/spacer to maintain that gap, might work for you here.

https://www.goodwins.ie/products/roll-out-rafter-vent-tray-600mm-x-6mtr-00520425.html

https://www.goodwins.ie/products/eaves-protector-tray-225mm-x-1-5mtr-ep15.html

But yes, get at least 150mm of insulation as far down that ceiling as you can.

DC999

https://www.boards.ie/discussion/comment/122846729#Comment_122846729

Thanks for those links. We've same roof type in Drimnagh. Must be thousands of old council houses in Dublin alone with that type of roof and insualtion problem.

Fern Bench

https://www.boards.ie/discussion/comment/122846729#Comment_122846729

Thanks for the links. I'll look into those. I might be back on here asking how to install them at some stage.

Pandoras Twist

https://www.boards.ie/discussion/comment/122846828#Comment_122846828

I'm in the same area, the eaves are only about 11cm, so you have to peel the rockwool when you're putting it down so that it doesn't touch the roof.

I got mine done professionally because I was too worried about getting it wrong but haven't had any issues since it was done.

As an additional fun fact, because the curved portion is only about 11cm, you basically can't get the SEAI grants, unless you also slab the interior ceilings with insulation board because you need to have 300m of insulation in all roof spaces. Slabbing is expensive and messy as you'll have to replaster every ceiling on the top floor. Nightmare.

kaizer13

A very common problem and not only with curved perimeter ceilings. The simple fact is that to install insulation correctly in those areas is difficult and can be physically challenging. As is also, the inspection of that work. Consequently, knowing that the householder is not likely to go to those lengths to examine the work and that they would not appreciate the difference between right and wrong installation. The cowboy insulation fitters continue to get away with shoddy work.

You may be able to find a conscientious and knowledgeable builder or even a handyman who is able, after inspection, to provide you with a practical and affordable remedy to the problem.

In the meantime, to minimise the occurrence of black mould, surface temperatures must not be allowed to drop below 16 degrees (difficult if the insulation is non-existent) so that means keeping the heating on or use a dehumidifier to lower the moisture levels of the air in the room so that condensation is kept to a minimum.