Mould under 1930 bay window

[chrisjjr1980]

Do you think I will need the insulation in your picture or would the insulated plasterboard suffice?

 

[JohnD]

The more insulation, the better.

 

[noseall]

Do you think I will need the insulation in your picture or would the insulated plasterboard suffice?

You need to fit as much as you dare between the uprights, whilst leaving a wee air gap on the cold side and then as thick as you dare (without compromising the window board) ACROSS the studs - prior to fixing the plasterboard.

 

[Diver Fred]

Have a look at

Should give you ideas and thoughts on how much you can do.

 

[Jonesy85]

Hi all, decided to tackle this myself. Wasn't expecting straight to brick wall. No going back now, but thinking I'll need to build inwards now with small gap from brick > insulation board > plasterboard?

 

[marc.knuckle]

Sorry to jump on this but i have a similar issue and will be working from the inside.
If i DO find any light coming through from the outside indicating a gap, what type of material would i use to fill it before then doing the insulation? Cement, plaster or something else?

Cheers, Marc

 

[JohnD]

Do you mean a gap in brickwork? Mortar

Or a gap round the window frame? Silicone sealant which I find much more durable than old acrylic. Clean away dirt and cobwebs. Apply timber preserver.

Some bays are just tiles on a wooden framework, and you need something to keep rain and damp out. Roofing membrane is probably best. Ideally applied from outside under the tiles, shaped so any water runs outside. You want to keep the insulation and the timber dry.

In dry indoor conditions you can use expanding foam to keep draughts and spiders out. It is messier and more tenacious than you think.

 

[marc.knuckle]

Do you mean a gap in brickwork? Mortar

Or a gap round the window frame? Silicone sealant which I find much more durable than old acrylic. Clean away dirt and cobwebs. Apply timber preserver.

Some bays are just tiles on a wooden framework, and you need something to keep rain and damp out. Roofing membrane is probably best. Ideally applied from outside under the tiles, shaped so any water runs outside. You want to keep the insulation and the timber dry.

Thanks John.

Outside it's like the original posters window, render. I think when i open it up there'll be something like thin wood slats that the render is stuck to maybe and i thought just in case i can see any light coming through, is it best to use something specific? It's definitely not bricks.

Thanks for the reply.

 

[JohnD]

It might be a wooden framework with wooden laths and render pressed on. When it rots and falls off you can do a more thorough job from the outside with cement board and breathable membrane. It will be better and fairly simple, and preferably use a scaffold or tower.

Mineral wool insulation is IMO better when you are fitting it between timbers into irregular gaps. You can nail foam board or insulated plasterboard to the inside surface. Run any wiring for sockets, TV or external lamps while you have it open.

As far as I can tell, ordinary mineral wool is not treated to repel water like the stuff used in cavity walls, so you must have, preferably breathing, barrier on the weather side, such as roofing membrane. You can use the same method on a good shed.

 

[marc.knuckle]

It might be a wooden framework with wooden laths and render pressed on. When it rots and falls off you can do a more thorough job from the outside with cement board and breathable membrane. It will be better and fairly simple, and preferably use a scaffold or tower.

Mineral wool insulation is IMO better when you are fitting it between timbers into irregular gaps. You can nail foam board or insulated plasterboard to the inside surface. Run any wiring for sockets, TV or external lamps while you have it open.

As far as I can tell, ordinary mineral wool is not treated to repel water like the stuff used in cavity walls, so you must have, preferably breathing, barrier on the weather side, such as roofing membrane. You can use the same method on a good shed.

Cheers mate and should i first fix any holes, however small, with something like cement?

i.e. fix with cement>breathable membrane>air gap>insulation> foil backed plasterboard>plaster

 

[JohnD]

Show us the holes.

 

[marc.knuckle]

Show us the holes.

I will hopefully be doing it in 2 weeks when I'm off so I'll check if there any and post on here.

 

[marc.knuckle]

I will hopefully be doing it in 2 weeks when I'm off so I'll check if there any and post on here.

Hi all, finally got around to starting this. Please see photos.

I pulled away a small part of the black cover and the concrete doesn't look too bad, I'm wondering whether i just patch up that hole with membrane and don't try to revcoat each section with concrete.

You'll see the lead and the gap between it and the window frame there's a gap right out to open air. Should i press it to the top and somehow seal it or shove something in there like silicone?

I'm thinking - existing black covering>air gap>foil backed foam insulation>moisture resistant plasterboard.
Maybe doesn't need a separate moisture barrier?

 

[JohnD]

The metal mesh (expanded metal lathing) and black roofing felt look like a fairly modern repair. I don't know what caused the hole.

If it was me, and I was working from inside, I would brush and hoover away all dirt and dust and use a timber preserver, then patch any gaps in the render with sand and cement, brushing on PVA solution first to help it bond, then staple roofing membrane to the timbers so that any penetrating rain runs outside, then fill between the timbers with mineral wool insulation, then apply an insulated plasterboard to the face of the timbers, skim or fill, and decorate.

Tack the lead flashing to the frame with large-headed clout nails so any rain runs outwards

If you have space for a thicker inner board, you could use a Kingspan or similar board with plasterboard on top. I favour boards with the aluminium foil cover as it is a barrier against moisture.

Loft rolls give heat insulation, but the denser and heavier cavity batts or sound wool will block noise better. Those tile hung bays are very insubstantial and let noise through as well as heat.

When the tiles or render fall off the outside of the bay, you will have access to give better weatherproofing and run membrane all over the outside, and a ply or insulation board, working from the outside.

 

[marc.knuckle]

The metal mesh (expanded metal lathing) and black roofing felt look like a fairly modern repair. I don't know what caused the hole.

If it was me, and I was working from inside, I would brush and hoover away all dirt and dust and use a timber preserver, then patch any gaps in the render with sand and cement, brushing on PVA solution first to help it bond, then staple roofing membrane to the timbers so that any penetrating rain runs outside, then fill between the timbers with mineral wool insulation, then apply an insulated plasterboard to the face of the timbers, skim or fill, and decorate.

Tack the lead flashing to the frame with large-headed clout nails so any rain runs outwards

If you have space for a thicker inner board, you could use a Kingspan or similar board with plasterboard on top. I favour boards with the aluminium foil cover as it is a barrier against moisture.

Loft rolls give heat insulation, but the denser and heavier cavity batts or sound wool will block noise better. Those tile hung bays are very insubstantial and let noise through as well as heat.

When the tiles or render fall off the outside of the bay, you will have access to give better weatherproofing and run membrane all over the outside, and a ply or insulation board, working from the outside.

It was me that cut away that section in the black felt to see behind. If i was to want to check all the render i would have to cut away the rest. I was thinking that as the felt looks like it's in good condition so hopefully the render is too, just to repair the hole i made with something like breathable membrane then do the rest of the things you've said but not to have to do the sand and cement bit

Also does the length of the clout nails matter or am i unlikely to go too far into the window base?