sash windows again

[plasticpigeon]

Hello again. I have yet another sash window question. I've now made and fitted the sash window. The builders I employed rebuilt the brick arch and squared up the opening but unfortunately I don't think they did a particularly nice job, but I will have to live with it. Maybe I will redo or at least repoint some of it at a later date, but for now I need to get the room habitable. My question is that there is a gap on the inside skin between the sash box and the window reveal. Originally this gap was stuffed with newspaper, the architraves put on and the whole lot plastered over. Does anyone see any objection to spraying expanding foam in there, or would the newspaper or something that just acts as a filler (fibrelass insulation) without sticking it all together be a better bet.

Many thanks.

 

[Lime]

DON'T USE EXPANDING FOAM!
It will prevent removal of the window in the future, may enter the weights area and is totally OTT in this situation.
Far better that you had flattened the brickwork (with mortar or polyfilla) on the inside of the reveal BEFORE putting the window back.
However putty or simple filler is all you need to use.
It was usual to have a piece of quadrant over the gap outside and architraves inside.
(nothing wrong using newspaper to fill a gap either)

 

[Moo]

I like the newspapers idea. Some future owner will find them fascinating.

 

[plasticpigeon]

Ah, yes I am planning to put a quadrant on the outside of the sashbox where it meets the inside of the outer skin. In fact the window is very close to the brickwork where it butts against the outside skin. It is between the sashbox back linings and the inner skin that there is a gap. I know it will be covered by architrave but I thought it might be good to fill the gap with something. I shall just use newspaper then, I didn't think about it being fun for future generations. However that assumes my house will last another generation!!!!!!

 

[Moo]

Which leads to the next big question: which edition of which newspaper?

Methinks a supply of KitKats should be on the next shopping list.

 

[plasticpigeon]

Here are the gaps. Not sure I have time for a Kitkat.

 

[AMc]

I'd be worried that a small ingress of water/condensation etc. or simply the moisture in your surface filler could turn newspaper into mush. If it were mine I'd probably stuff fibreglass insulation in there then cover with a filler/mortar.

 

[Schoolmarm]

I have to confess to using chopped up car was sponge, it pokes right in and stops all draughts. I meant to take it out before the plasterers started though.

 

[Lime]

I'd be worried that a small ingress of water/condensation etc. or simply the moisture in your surface filler could turn newspaper into mush. If it were mine I'd probably stuff fibreglass insulation in there then cover with a filler/mortar.

I had assumed the newspaper filler or whatever is to be plastered over?

Plaster is not going to collapse even if the paper were turned to mush but I think I'd be much more concerned about the saturated plaster and wood by that time if it were to happen.

 

[Lime]

However, looking at the last picture again, the sill needs to be supported by something substantial.
Bricks would be a good idea.

 

[plasticpigeon]

The window is really hanging of the top horns, that was how it originally was!It is also sitting on a blue brick sill, and will need the small gap between this and the wooden sill to be sealed. I will have to put bricks under the bottom horns for support though. The gaps at the side will be covered by architrave, so once plastered there shouldn't be any gap as such, I just thought it prudent to fill the gaps with something before plastering.

 

[AMc]

I wouldn't leave a big void to allow the wind to whistle around the window but I'm not any kind of expert so feel free to ignore my thoughts
Half hearted fitting and filling between the new window boards/cills and walls in my bathroom resulted in quite a draught. One of the many things that I had to "fix" after the builders left.

I recently found a sealed old copy of Green Building Magazine from 2009 - I didn't have time to read it while the renovation was in full swing - it had an article on convection losses within poorly sealed insulation which frankly made me want to cry - they showed serious implications of 1-3mm gaps in substantial amounts of high performance insulation. The devil is in the detail, if only I'd really known

 

[Lime]

I wouldn't leave a big void to allow the wind to whistle around the window but I'm not any kind of expert so feel free to ignore my thoughts

Oh! I agree, but the important things to remember with sash windows is that they need to be installed in such a way that they can be removed in one piece and that whatever fills the voids does not enter or compress the weights boxes.
My comment re. newspaper being ok was in contrast to expanding foam!!!