Fitting a Window Sill (& window) to new opening

Dustypig

Hi All,

This is our first post so hoping someone can help

We are converting an old unloved room into useable living space. The problem is that it only has 1 small window so we need to fit 2 new ones.

We have cut new holes in the walls, fitted new lintels and made cut outs for the sills to fit in.

The walls are typical 1970's cavity block walls (double 4 inch solids tied together with metal straps & no insulation in the cavity).

Questions are:

1. How to fit the sills (do they sit across the cavity or on the outer blockwork)?
2. Does the DPC under the sill run up the sides of the window hole and for how far?
3. How to we close the hole in the cavity (looks to me that the new window wouldn't do it on it's own)?

This is very much a "learn as we go" project so any advice appreciated.

Thanks All

Fries-With-That

Dustypig wrote: »

Hi All,

This is our first post so hoping someone can help

We are converting an old unloved room into useable living space. The problem is that it only has 1 small window so we need to fit 2 new ones.

We have cut new holes in the walls, fitted new lintels and made cut outs for the sills to fit in.

The walls are typical 1970's cavity block walls (double 4 inch solids tied together with metal straps & no insulation in the cavity).

Questions are:

1. How to fit the sills (do they sit across the cavity or on the outer blockwork)?
2. Does the DPC under the sill run up the sides of the window hole and for how far?
3. How to we close the hole in the cavity (looks to me that the new window wouldn't do it on it's own)?

This is very much a "learn as we go" project so any advice appreciated.

Thanks All

Window Cill sits on outer wall with DPC under and coming up both sides, AFAIK you have to use 9 inch.

We used expanding foam to bridge the the gap at the sides and top of the window.

We made sure that The DPC was against the outer wall up both sides of the window too.

AckwelFoley

You have to put insulation behind the cill 1" to prevent cold bridge where the window board will be

dharn

You should get the cavity filled with foam or bead, makes huge difference to the heat in the house