Bedroom Bay wall - Replastering/insulation?

[Jumbo Jim]

Hi,

I have had what appears to be either a penetrating damp and/or condensation problem in a bedroom bay wall. Pic below shows the worst section of staining but other areas of the bay also suffered from dampish wallpaper so I decided to remove all the plaster in this area (possibly foolishly).

The wall is solid brick (no cavity) and when I removed the wallpaper could see the worst section appeared to have been patch plastered. I'm presuming maybe if water has been coming in at this point it may be a recurring issue in the house.

Trouble is I don't know what's best do do from here - there more I read the less I know i.e. re-plaster with a lime plaster allowing wall to breathe etc - also advice on insulation seems to be a bit of a rabbit warren with warnings about causing greater problems than you're solving.
Also seen warning about needing to insulate voids under floorboards etc near bay if you are going to insulate wall.

Can anyone provide any pointers or steer me to a link about best way to deal with this ?

Bay Window3

• Jumbo Jim
• 12 Nov 2019

Bay Window2

• Jumbo Jim
• 12 Nov 2019

Bay Window

• Jumbo Jim
• 12 Nov 2019

Bay Window4

• Jumbo Jim
• 12 Nov 2019

 

[KeenDIYer87]

I'm no expert but I own and live in a Victorian house of similar construction and have experienced similar problems. First thing I would check for is loose/missing pointing on the outside of the bay or cracks in render if it is rendered.

The whole "allowing the plaster to breath" is so that warm air in the room doesn't settle on the internal cold surface of the wall, creating the problems you've experienced with paper coming off or worse - mould. My personal opinion is to not allow the internal surface to get cold in the first place by insulating using wooden batons, insulation boards and plasterboard. Create your own mini cavity wall with the batons and insulate. For a bay window you would have to extend the sill which adds to the work. As stated earlier, I'm no expert but that is how I would do it.

 

[JP_]

I'd stick kingspan (or similar) to the wall, plasterboard over and skim. For good insulation go for 50mm, but to stop condensation 25mm will probably be enough, and easier to make good.

Insulating the floor is always a good idea, but it should not be required to stop the wall getting damp. Be sure to seal insulation boards with silver insulation tape to prevent moisture from room getting to bricks (do same if you insulate floor with kingspan).

Saying all this - I did not insulate my bays because I had radiators in them. No damp problems there.

My 1930s bungalow - insulating ... note the Cillitbang black mould remover - sprayed that everywhere before covering with insulation!

floor

finished job

One year on and not a drop of mould.

 

[SFK]

Looks like Jonbery is doing the same as I am doing to my house.

I did have to insulate the bay.
So I did similar to keen:
- re pointed bricks with cement mortar
- Put in treated wood batons screwed to wall using Framing Screws (I used treated 25mm deep battens from wickes as I used 25mm PIR there as was linted on space.
- Note that for speed I put up battons by hand pushing them aganst wall, and drilling pilot hole straight through wood and into brick using a singe masonary drill bit, poping in framing screw and hitting it home with hammer (this is how you are supposed to screw in Frame Screws).
- Put PIR between each batten.
- Tape up all battens and PIR joints with metal tape
- Screw plasterboard onto battens.

I was luck as window cill over hang by ore than 25+12mm, so I did not have to change it.

https://www.wickes.co.uk/search?text=Wickes+Treated+Sawn+Timber+-+25mm+x+38mm

https://www.screwfix.com/p/easyfix-frame-fixings-8-x-100mm-10-pack/19356
SFK

 

[Jumbo Jim]

Thanks for the heads up. My thoughts right now is to monitor it to see where the water is coming from and attack it properly when we have longer and warmer days. Just need to put the heavy duty quilt on for a couple of months.