Window reveals and insulation

[thatsnotafestool]

Will be making some new windows to go into the wooden frame of the black-and-white I'm doing up.

The reveals are rotten and so it's replacement of the lot (done under Building Control Notice). Frame sized to be a snug fit into the timber frame, gaps filled with what? Expanding foam?

Window reveal inside...just plain old wood or did I remember reading somewhere that I need to fix a slab on Kingspan or similar in the reveals between the oak frame and the wooden reveal. If the latter then what do I use to cover the 75mm edge of kingspan that I'll see from the outside? Will mean making the windows smaller as well by 2 x 75mm or whatever.

many thanks

[jfc]

The timber is the insulator in this case so no kingspan , leave that for the voids between the stud work . I would fill the gaps out side with mastic as they are only going to be a few mm and yes timber reveals inside fixed and packed so level straight to the stud work .

[dirtydeeds]

i use expanding foam when re installing or repairing box sash windows

(its only a modern equivilent of the rubbish they used in the first place, generally some form of plaster or very very weak lime mortar with wood shavings, sawdust or horsehair as a binder)

timber has a very high insulation value


if its being done under a notice, i would check before making the windows smaller and especially if its in a conservation area

and even if it isnt i certainly wouldnt do this to a building

[jfc]

Erm the crap they used was folding wedges
Expanding foam is not the best thing to pump around a sash as the backing to the workings is normally very thin . Ive had expanding foam push a sash out of square before as they are not made from the best form of construction . Nice windows but the frame construction sucks .

[dirtydeeds]

jfc

i make and repair box sash windows, i also make and repair modern windows

box sash frames are hung and clamped

they dont need wedging and never did

box sash frames are stiffer than modern window frames

and any fool can bend anything (including a box sash frame) with too much foam

[jfc]

Box sashes where always held into the brick reveal with folding wedges and then plastered up to . Hung and clamped All the ones i have replaced where nailed together with brads .

[dirtydeeds]

the inner cheeks are left long so you can hang them from the inner timber lintol, traditionally they are nailed (i screw them its easier)




clamped for and aft in the opening (having squared them up) and the voids filled (these days with foam) then plastered in

i ve done this with frames up to 4' x 7'6" this is a frame i made on site last year



when they are this big you DO have to be careful with the foam


i didnt take photos of the install, its so obvoius to me its not worth taking a photo

agreed, nailed together with brads, 2 and 3 inch nails, personally i use a pin gun and glue on the frame repairs

[jfc]

Well why didnt you say fixed at the top ;D Foam is good but it does break down over time leaving nothing ( time will tell as it's quite new) holding the window in . I like a few folding wedges holding my box sashes in myself .

[dirtydeeds]

i thaught hung was sort of fixed at the top

then i realised what you ment................... hung is ..............only until you are dead

not nailed in the head and left to rot, like most owners of box sashes treat them

yes im not sure on the longevity of foam but you can usually hoover out the rubbish they used to use

[dexteria]

I also use folding wedges to hold the box in place but I sometimes wonder about this as any windows that I've removed, the wedges were loose or had falled out with the whole thing being held in with the panneling and/or inoperational (usually) shutters or worse still plasterboard.

I would worry that using foam would lead to lack of ventilation and possibly rot where moisture would possibly be in contact with the unprotected inner faces of the box.

I use paper soaked in linseed oil to pack out between the reveals and the box finished off with a lime/linseed putty mixed with sand and moistened with more linseed oil. I was told that Scottish Herritage require it done this way although I've never had any dealings with them myself.

Cheers

Mark

[dirtydeeds]

its not the first time ive heard of this method

but it is for the exterior. the gap between the brickword and the outer cheek/head rather than the void on the inside wall of the building