Insultating the back of a cupboard with solid walls

Postby Ian Dudley » Mon Sep 13, 2010 11:53 am

Hi, I have a 1920's detached house, with loads of condensation problems thanks to over-insulation by previous owners. Every winter we get loads of damp and black mould thoughout the house.

I'm starting a number of projects to attack this, first of which is a couple of built in wardrobes in the master bedroom. These get lots of mould which is ending up on my wife's clothes, so it is right at the top of the priority list! :)

The cupboards are fitted wood construction, floor to ceiling against a solid brick external wall. One is between an closed chimney breast and external wall (i.e. it covers the corner of the house), the second is between the other side of the chimney breast and an internal wall, so only the back of that one is external. The external wall is normal solid wall construction, with a render coat on the outside that's been painted with Weathershield type stuff. Immediately above the cupboards is the loft, which has bits and pieces of insulation but doesn't seem to be ventilated at all (which is probably project number two). The external wall in question is north facing.

Even with everything else I'm doing, we're going to really struggle to get decent ventillation in these, due to them being packed with clothes and being built out of walls on three sides (if you include the Chimney). In the winter, you call feel how cold the extrenal wall is, and being in a bedroom there is quite a bit of warm moist air floating about. Plus both are lined with wallpaper which merrily absorbs the moisture to provide a cosy home to black mould.

I have the following plan to try and fix this without major work and was just wondering if some more knowledgeable people than me could give me an opinion on how well this will work and any potential pitfalls.

I'm planning to take out the internal shelves, etc, then strip the wallpaper. I'll then clear out any mould with fungicide, make sure the wall is sound (it appears to be from investigation) and paint with a fungicidal paint. Then I plan to line the external wall parts of the cupboards with an insulating laminate, something like polystyrene or Sempatap, that kind of thing. On top of that I'll then put some thin wood board to make a new wall surface, which will then be painted itself with fungicidal paint. I plan to use a relatively thin sheet of insulator, as I don't have much space to play with within the wardrobe and still leave it useable. Not sure about fixings yet, might glue the insulation on, but will probably use screws through to the wall for the wood board as it's thin and will need to be held fairly rigidly.

I'm hoping that this will provide enough insulation to avoid the wall surface geting cold enough to generate the condensation. Bear in mind the room itself is kept reasonably warm, its only these walls in the back of the cupboards which get this problem (in this room anyway). Getting rid of the wallpaper will hopefully help as well.

As it's a cupboard lining, I'm not too worried about how it looks, provided I can finish it neatly. Plus we won't be mounting anything on the wall so it doesn't need to be structural. I'll also probably cut a couple of vents into the cupboard to help with ventilation (there is a thin strip of thin wooden wall proud of the chinmney breast on each side which would be ideal for this).

I'm aware that this sort of lining can cause issues of moisture within the walls, but I'm hoping that since I'm only doing this in a realtively small area at the back of the cupboards it won't be severe enough to cause any problem. Plus I won't be lining the chimeny breast side (as it doesn't get particularly cold), so there should still be ventilation into the walls through that.

Overall I recon I can knock this out pretty cheaply and quickly, probably a weekend per cupboard, and score some good kudos with the wife.

Do you think this will work? (having the mould come back, even if at a reduced rate, would be bad for my kudos and health in general) Also, are there any pitfalls I should be careful of, or is the whole thing a long term bad idea in general?

Any advice appreciated.
Ian Dudley
Posts: 8
Joined: Fri Dec 05, 2008 11:18 am


Simply Build It

Postby Ian Dudley » Tue Sep 28, 2010 8:53 am

Not having had any responses I thought I'd post a quick follow up for anyone who wanders in with a similar problem.

Having scouted out various insulation options at my local DIY stores, I settled on some Warmaline thin polystyrene veneer. Very cheap at £3.50 a roll, vs £20 plus for smaller sheets of thicker stuff, plus it won't eat into the space in the cupboard. Plan was to double line with this stuff, overlapping the sheets so there is no gap through to the wall. Then cover with thick lining paper (1700 stuff from Wickes) so as to protect the rather fragile warmaline. Then a final coat of mould resistant paint. I also painted the bare walls with the mould resistant paint after stripping the old paper. As soon as I put up the warmaline you can feel the difference to the touch, the wall feel warm on the veneer and cold on the bare wall right next to it, so fingers crossed this will stop the condensation forming on the wall in the cupboards (I know it will go elsewhere, but I can deal with it easier in the open away from clothes).

A few tips for anyone working with warmaline. You essentially treat it like wallpaper. Cut it to the rough size you need but with excess all round, slide it into position then trim. It's really fragile though so you need to be very careful. I also recommend you use an extremely sharp knife for trimming, as the slightest snag will cause the stuff to rip, which is hugely frustrating. In fact a good thing to get is one of those small wheel wallpaper trimmers, like a mini pizza cutter. It does a great job of cutting warmaline as it rolls and so won't tear the stuff. Not easy to use on the wall, but excellent for trimming on a wallpaper table or making small patches to a particular shape.

The only other recommendation I'd have is to avoid the Warmaline branded adhesive, as it's expensive and useless. Despite following all the instructions and leaving it to dry for the recommended time, it all started to peel off in great big sheets when I put on the lining paper.

Just to add insult to injury, when I went to get some more I ended up at Wickes and bought thier own brand version of Warmaline. They don't stock the warmaline branded adhesive, and instead recommend using standard ready-mix wallpaper paste. This was £5 for 5 litres, compared to about £13 for 2.5 litres of the Warmaline stuff, and is a much, much better adhesive. Holds the veneer on a lot stronger and I haven't had anything peel off where I've used that.

Sadly pretty much everything I did with the Warmaline glue has come off, so I'll need to completely re-do those sections using the wallpaper paste. Hopefully I can keep the sheets intact though so they will still fit and just need sticking back up. Bearing in mind that for the volume the warmaline glue is 5 times the price of ready mix paste (and even more times if you mix yourself), I have to say it's a complete rip off.
Ian Dudley
Posts: 8
Joined: Fri Dec 05, 2008 11:18 am

Postby welsh brickie » Tue Sep 28, 2010 3:54 pm

really ventilation is the key,cutting a vent through the back of the wardrobe to the outside is the key and then fitting a hit and miss vent internally and a plastic vent to the outside is the best solution.
With regards to the wall inside the cuboard you could use cork tiles to insulate the wall and glue them in place
welsh brickie
Posts: 2155
Joined: Sat Apr 12, 2008 7:54 am

Postby Ian Dudley » Thu Sep 30, 2010 9:02 am

I'm putting internal vents in the cupboards at floor, head and ceiling height, plus some internal vents between the different sections of the cupboard to help the air circulate. Knocking through to the outside isn't really going to be a goer. Would need scafold in the neighbours side passage, plus the outside is rendered so that would need sorting. Way too much hassle for a cupboard! I'd rather knock down the fitted wardrobes and put in standalone than go through that much faff. Hence I'm hoping that better insulation in the cupboard plus some internal ventillation will sort the problem. Fingers crossed!

Incidentaly, all the existing sheets that came off were useless. The lining paper had gone stiff and couldn't be made to sit on the wall properly. so I bit the bullet and pulled it all off, which leaves me back to a single veneer of warmaline again. Really annoyed with how useless the warmaline adhesive was. Total waste of money and now I need to buy more veneer and paper plus spend another weekend faffing about with delicate polystyrene!
Ian Dudley
Posts: 8
Joined: Fri Dec 05, 2008 11:18 am

Postby welsh brickie » Thu Sep 30, 2010 1:54 pm

dont use polystyrene or warmaline they produce surface moisture use a carpet tile or cork but stick them with bitumen paint to stop moisture penitrating
welsh brickie
Posts: 2155
Joined: Sat Apr 12, 2008 7:54 am

Postby Hirenashiani » Fri Jan 11, 2013 1:03 pm

Hi there.

I have exactly the same issue am I will be installing vents into the fitted cupboard so that the heat generated from the radiators in the room will car any condensation/ moisture in the cupboard.

Did your fix work? And issues in the winter?
Posts: 1
Joined: Fri Jan 11, 2013 12:57 pm

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