Insulating a damp bathroom that already has exterior render?

6 years ago

Hi all, looking for some advice.

Our Victorian mid-terrace has a problem with condensation in the downstairs bathroom. It's a solid wall brick extension (30s/40s?) so the walls get icy cold in Winter and it is impossible to heat. The cold walls (on 2 sides) mean we suffer heavily from shower steam condensing, ruing the decor and causing mould.

I'm exploring options for insulating and improving the room. Ideally I'd like to use internal insulation because it's cheaper than external insulation and we could install it ourselves - even if it means going back to brick.

I was looking at replacing the extractor with a more powerful model, then lining the walls with waterproof insulated tile backer boards, with floor-to-ceiling tiles to the face.

However I've been told by a friend that we should be careful as the exterior of the walls are completely rendered and we risk trapping moisture by not allowing the walls to breathe.

Is this advice correct or can we somehow safely insulate the bathroom internally? I think that external insulation is going to be out of our price range as it is not a DIY job.

Comments (4)

PRO
Opun
6 years ago
Hi Guy,

Internal solid wall insulation usually involves fitting ready-made rolls or boards of insulating material over the inside walls of your house. This can be disruptive - You may need to relocate, radiators and fitted furniture as well as a slight reduction in floor space owing to the extra thickness of insulated walls. . Your walls will need to be carefully prepared before internal wall insulation can be fitted. Any damaged plaster needs to be either repaired or removed, and bare brickwork should be treated to eliminate areas where air can escape. We would also suggest painting on a waterproof paint on the wall so no water penetrates past the brick.

Hope this helps?

For more tips and advice check out our blog. We love sharing our expertise as we build lofts, extensions, bathrooms, and kitchens all the time :).

Opun - your home improvement experts
Guy Incognito thanked Opun
Guy Incognito
Original Author
6 years ago
Thanks for advice. We're prepared for the slight loss of space and disruption. We're actually also anticipating having to remove the old plasterwork so the total space lost will be minimal anyway. Would you say then that it is safe to insulate internally even though the exterior of the walls are sealed by render?
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Bah, wrote a long reply and it all disappeared! 😥 Anyway, it was saying I finally managed to get a builder here AND a quote from them, lol. Was £760 to put a window in NOT including external rendering (pebble dash!) or internal plastering etc so it’s a lot of money. It can’t be too deep either because I didn’t realise the outside gate is in the way so it will end up just being a narrow slit. However, he was a nice guy and knows my neighbour well (who recommended him) and he asked to look in the loft space and said we could actually have a velux on the side which we didn’t think we could have. He doesn’t do them (need a roofer for that) but he said it would need a joiner to create a tunnel inside. Next step is to get prices for that but our roofer is booked up for another month with roof repairs (including one for us!) so will have to be patient, bah. Lol. Internal window idea - we were going to do that and if the velux is too expensive then we still will. Will be better than nothing I guess but not very bright. Sun tunnel would probably cost the same as a velux to put in but the latter will give us more light so ..... Watch this space!
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PRO
Flint and lime
6 years ago
Hi There - Have a look at this product if you require further advice please feel free to contact me -

http://bauwer.co.uk/
Guy Incognito thanked Flint and lime
Guy Incognito
Original Author
6 years ago
Thanks Dylan - this is an interesting product. Are you suggesting this to replace the external render?

Insulating a damp bathroom that already has exterior render?

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Insulating a damp bathroom that already has exterior render?

Comments (4)

Opun

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Flint and lime

Guy IncognitoOriginal Author

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Guy Incognito
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Guy Incognito
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