Fitting new timber windows

[paulb33]

Happy New Year to all. A quick question: what is the preferred way to seal around new timber windows? My new wooden frames will be installed into brick and roughcast rendered elevations. Is there a product that i should insist is used to seal the frames (internally & externally)?
Regards,
Paul

 

[plasticpigeon]

I live in a cheap Edwardian house with sash windows. As far as I can tell there was nothing bedding the windows in. The windows were fitted from the inside and butted up to the inside of the outer leaf or brickwork. The small gap between window and brickwork was covered by a scotia bead. On the inside obviously plaster and architrave covers the gap. I think the most suitable thing for sealing the outside gap would be trowel mastic (sand and linseed oil). The modern method is to fill any void with expanding foam. Although i don't care for that idea, I'm not sure I can think of any real problem with it other than it gets everywhere and is difficult to remove if needed.

 

[Roger H]

Expanding foam filler. I’d suggest masking tape to surrounding areas and then fill her up. Then when it is set excavate it out an inch or so on the outside and insert appropriate period filler – burnt mastic.

 

[DJH]

I agree but I would use a strip of damp course fixed to the top, sides and bottom of the frame to isolate the wood from any damp in the masonry/brickwork. Expanding foam negates the need for fixings, such as screws which might penetrate the dpc, and will act as an insulating barrier between the cold walls and window frame. A smearing of Vaseline or silicone grease on the dpc will prevent the foam sticking to it so future replacement of the windows will leave the foam in place.

If the windows are being fitted from inside, up against render for example, a fillet of a polysulphide type mastic on the edge of the frame will help weather that joint.

Angle brackets can be used to fix the windows on the inside if you wish, which keeps them inside the building in the dry, avoiding rust or corrosion and leaving them accessible for any future work/maintenance etc.

I know this will excite some people but it's how I've fitted my windows and I'm more than relaxed about the method I've used. I bet period builders would have used foam if they had it... 8)

Doug

 

[88v8]

Trowel mastic
http://www.everbuild.co.uk/index.php?route=product/product&product_id=163

Other trowel mastics are available.

Ivor

 

[paulb33]

Thanks all. The joiner mentioned mastic, which troubled me (hence my question). Looks like it might be OK.

 

[skier-hughes]

Depends on what mastic he was talking about They aren't all the same.
I've used oak wedges to hold in place and burnt sand mastic to seal.