Sealing Bay Window Surround

[macker6464]

I have posted before about my whistling windows and fixed a few through removal and binning the plastic trim, filling, caulking and painting. Looks good and no whistling.

Now I have started on the lounge bay window but the gap is rather huge. I have removed a piece of trim from the front right and the gap is big. I can get my fingers in and push the outside of the house side trim which is not sealed down very well. No wonder the area was cold and whistley!

Should I fill with expanding foam and then seal up with filler and/or do I need to re-use the trim pieces and glue them on properly?

Should the gap be left full of air to stop condensation or something? Does the foam insulate?

Any ideas appreciated.

The photos give you an idea of what I am talking about.

Also if I did use expanding foam how would I stop it coming out the trim on the outside of the house? Can you trim it back when it sets?

If I clean up and reglue the trim on what adhesive do you use?

Cheers

Macker

Bay Window

• macker6464
• 18 Feb 2015
• 1

Trim removed on RHS

RHS showing removed trim

• macker6464
• 18 Feb 2015
• 1

Large gap between wall and frame

• macker6464
• 18 Feb 2015
• 1

Fingers pushing external trim

• macker6464
• 18 Feb 2015
• 1

damp proof layer at side

• macker6464
• 18 Feb 2015
• 1

Large gap - stuffed with green plastic bag

• macker6464
• 18 Feb 2015
• 1

Ouside view of bay window

• macker6464
• 18 Feb 2015
• 1

loose trim on outside

• macker6464
• 18 Feb 2015
• 1

 

[JohnD]

I got a neat job by tacking a batten on the outside to prevent the foam oozing out.

the foam is very sticky, so wrap the batten in clingfilm first or it will be difficult to remove later.

Also cover the brickwork and the frame with tape and clingfilm so it is not marked by the foam.

In my case I had a wooden trim round the windows so the batten was suitably stained and retained as part of the trim.

On the inside, protect the frame and the face of the wall in the same way.

Clean out the gap to remove all dust and dirt first, and spray it with water, both to wash out dirt and to leave the surfaces damp, which helps the foam expand and harden.

If you run wide tape over the gap on the inside, and poke small holes through it every six inches or so, you can inject through the holes. Poke the nozzle into the centre of the gap. Start at the bottom. Patch over each hole with more tape after injecting. After you have injected into one hole, wait until the foam has stopped expanding before you inject into the next higher one. If you leave nowhere for it to expand into it may put pressure on the frame or wall.

Spay water on any gobbets that fall out to form a hard crust which will reduce them sticking to whatever they touch. You will need good floor coverings and a lot of disposable gloves.

The foam breaks down in sunlight so any foam exposed on the outside needs to be covered, or painted, or sealed over with dark silicone. Once fully hardened, you can trim the foam with a serrated knife or coarse sandpaper.

 

[Gazman16]

Masking tape every thing 1st too, If you use the cheap disposable diy cans of foam it will go everywhere