installing sash windows

[plasticpigeon]

Hello. I have been doing up some sash windows recently and am looking for some advice on how to best fix sash windows in position. In my house the windows were built in, the arches brick being built onto the top of the window frame (which has bricks forming an arch behind the arch filler. They are also fixed into position by mortaring round the horns. this seems a poor way of fixing the windows in, and means that the springer bricks on on either side of the brick arch only exist on the outer skin and the inner side of the arch is not really supported (once the mortar has crumbled and the house has moved a cm or 2!!!) In one book I have it talks of building wooden bricks into the brick jambs in the inside or hammering in wooden wedges and then skew nailing the window into its recess through the inner and back linings. Is this a good or the best method? It seems to me a better method would be to make the inner linings wider so that they overlap the bricks and nail or screw through them, but i am restoring old ones and only replacing the sills. i would be very thankful for any advice.

 

[agbagb]

Well this is the rather unconventional way I retrofitted mine.

A small bit steel cut from a joist hanger screwed to good bit of brick.

When the frame is in, bend it over and screw in to the sill and another one in the top rail. The tabs are covered by achitrave or hidden by spacer linings if the wall is thicker.

Try and avoid fixing the outer edges of the linings. If you do, any expansion can pinch the sashes.

 

[plasticpigeon]

Thanks agbagb that makes sense. I could do something similar on the sill, but not at the top as there are linings all the way round that are proud of the brickwork. i could perhaps screw into the side of the head in a similar way.

 

[agbagb]

Without bending it round. That would work.

sorted!

Could this be the shortest ever thread?

 

[Andrew Bodenham]

I've just installed some new sash windows in my limestone rubble house.

I secured them by sprayfoaming between the internal lining and the stonework of the reveal. No mechanical fixings were used. The sprayfoam provides draughtproofing, thermal break and moisture resistance, as well as mechanical fixity.

Externally a lime mortar bead closes the gap between the stonework and the side of the window. At the bottom there is a generous gap to allow water to drip from the wooden sill onto the stone sill - further back the wooden sill is sealed down onto the masonry with a thick bead of elastomeric sealant as a second line of defence. At the head a piece of plastic dpm material is dressed over the top of the window to shed any water which runs down the inside face of the external stone lintel. The head is left un-mortared in order to ventilate the wall core in the lintel area - helping to keep the internal timber lintels dry.

This method provides two layers of defence against moisture penetration in susceptible areas, and creates a drained and ventilated cavity to the sides and sill area which will allow any moisture to escape.

In my opinion it is no good relying on a fully water-tight seal around the outer face of the window as this will inevitably fail in time. The detailing should anticipate some penetration of water, and allow for it's removal by ventilation.

The use of sprayfoam may raise a few eyebrows, but my experience leads me to believe that it can have a useful function in certain applications. Having just removed a number of "temporary" windows which were secured with sprayfoam 15 years ago I was pleased to find that the materials remained elastic, and was tenaciously adhered to both stone and timber. In contrast I have often come across failures in silicone and oil-based mastics, and situations where metal mechanical fixings have corroded away or where expanding rust has split woodwork allowing ingress of water.

Detailing is everything when creating junctions between different building elements, and each case needs to be carefully considered in terms of water management. A mix of traditional and modern materials may be appropriate.

 

[dandrew]

The traditional method used 'folding wedges', whereby a pair of wedges were hammered in between the box of the sash frame and the reveal in the brickwork. Typically 1 pair was put in at one end of the cill and 2 pairs went in between the head of the box and the lintel. Wood bricks are only practical when you are building the house at the same time. If you are repairing old ones is it not better simply to copy the previous method ?

There was sometimes also a water bar bedded into the masonary cill with 'white lead' that fitted into a groove in the wooden cill.

David

 

[DJH]

I have fitted eight new replacement four pane hardwood windows here and am lucky enough to know a glazier and he sourced me some old float glass which matched the original wrinkly glass. The light now reflects from different angles outside instead of the single flat black reflection from modern glass.

Anyway, I’m a firm believer that where timber touches stonework a damp proof membrane should be used so that the wood doesn't come into direct contact with cold, damp or ‘heaving’ stones which can cause subsequent decay and rot.

Contrary to all advice from the conservation groups and experts my previously white washed rubble masonry has been encased with a cement based render which, as it’s an old farmhouse, was rendered in the late 60’s when regulations came in for farms to plaster dairies and milking parlours for hygiene purposes. They probably took the opportunity to get it done while the plasterers were on site!! This hard render has in fact, preserved the house during the time it stood empty (nearly 45 years) and made it easier to fit the widows as they butted up to a nice straight edge which I applied a squirt of Calder’s grey coloured lead sealant mastic as it doesn't set hard and the windows are painted grey anyway.

Like Andrew I used some ‘squirty’ foam to both hold the windows in place and also to act as an insulating layer between stone and window timber. With inside shutters on each window the ply window linings are also fixed with foam and the added bonus is that we don’t suffer from condensation in the corners like chuckey does in his post 13th November.

 

[Lime]

God help the person who has to remove these windows in the future.

 

[DJH]

I know what you mean Lime but I don't expect it will be me.

Seriously though, shortly before I retired it was becoming mandatory on certain high value jobs, churches, historic houses and even new build, to hand a 'log book' to the owner or their agents which explained in detail all the works carried out and methods used along with annotated drawings. This seems most sensible to me and if we all did it it would be a great help to those who follow us......

 

[DJH]

God help the person who has to remove these windows in the future.

I've been thinking about this Lime and I believe taking a window out that has been fixed in the way I have fitted them will be a simple job. The common way of removing timber framed windows is to remove the glass or frames, cut the sides of the frame at an angle and lever off the part of the frame that has the upwards or outside cut. The side fixings, be they nails or screws, are usually cut between the frame and wall using a reciprocating type saw.

To remove my windows the shutters and inside cheeks have to be removed (they are screwed using stainless steel nails) and either a wood saw or padsaw to cut the foam and then the frame will come out complete. Simples?? 8)

 

[LadyArowana]

God help the person who has to remove these windows in the future.

God helps those that help themselves. In any case he has little standing in such matters having done a rather rushed bodge job of the earth in 6 days, maybe if he hadn't taken Sunday off, or better still done the work over a month or so there wouldn't be so many issues now.

 

[Lime]

God help the person who has to remove these windows in the future.

I've been thinking about this Lime and I believe taking a window out that has been fixed in the way I have fitted them will be a simple job. The common way of removing timber framed windows is to remove the glass or frames, cut the sides of the frame at an angle and lever off the part of the frame that has the upwards or outside cut. The side fixings, be they nails or screws, are usually cut between the frame and wall using a reciprocating type saw.

To remove my windows the shutters and inside cheeks have to be removed (they are screwed using stainless steel nails) and either a wood saw or padsaw to cut the foam and then the frame will come out complete. Simples?? 8)

You obviously have not tried to cut through mature hardened foam securing a large object that you wish to remove intact.
Expanding foam is one of the worst materials to use on period property because it cannot be removed without damage to structure.

If you think

The common way of removing timber framed windows is to remove the glass or frames, cut the sides of the frame at an angle and lever off the part of the frame that has the upwards or outside cut

you haven't done this very often have you?
I've removed dozens of complete sash windows in my time without having to cut or break any of them.
Sash windows were designed to be simply secured so that removal was able to be done with minimum damage.
Using an adhesive to secure them in place effectively consigns them to the scrap heap when they need removing again.

 

[plasticpigeon]

I know squirty foam makes some sense, but I just couldn't bring myself to do it. I do like agbagb's method which would have worked well at the bottom of my window, and I could have made it work at the top of my window but it would have needed some packing pieces at the top as I couldn't bend the tabs over. In the end I skew screwed through the inside and back linings to wooden wedges I put in the wall. I am not totally sold on this arrangement but the window was quite a tight fit anyway and I like the idea that it can be taken out relatively easily if need be. I didn't think this would be very strong, but it seems solid enough with only 4 screws.

The first window I did, I put back the way it was originally put in which was to wedge the horns and bung up the gaps between horns and brick with mortar. That really will be a pain to take out if need be!!! However I am so pedantic about original windows I would always find a way of removing them whole, even if it meant disassembling some brickwork.

 

[DJH]

Hmm you are making assertions as to what I have and haven't done Lime. Read my posts again and you'll see that we basically agree apart from the use of foam. Using it in the way I have around these windows can only enhance the life of the window itself by isolating it from cold, damp and on more than one occasion wet masonry. The softwood windows I removed were beyond repair, not economically but physically. I did consider the use of chemical fillers to repair them but I'm afraid that there would have been more filler than timber so I had new hardwood ones made, each one a different size, replicating the originals and glazed with 'old' glass.

I also mentioned in an earlier posting that my house is constructed from rubble stonework so I maintain that by using foam in these circumstances I have obviated the need to 'damage the structure' by removing the rubble and building back new reveals. The foam has an added bonus that it holds the window in place without the need for for fixings although I did use modern stainless steel screws to reinforce the fixing of the windows and a vertical damp course on the sides of the window which isolates the foam from the window. The rubble in the wall is also consolidated by the foam.I didn't use foam without considerable thought and came to the conclusion that under these circumstances it is the best solution.

I'm afraid that 'not damaging the structure' is a creed we cannot possibly adhere to in trying to maintain,conserve or repair our heritage. I'm also sure that by the time my windows need attention the people carrying out the work will be well able to remove 'old foam'.

I can't resist the old chestnut that had a lot of these materials been available back at the time they would indeed have been used.

Later edit.....

I recall many historic buildings which have benefited from the use of modern materials and treatments. Ightam Moat, Uppark, Lulworth Castle, Windsor Castle, Ely Cathedral the list goes on................

Ightam Moat,for example, one of the 'jewels in the crown' of the National Trust had gallons of PU resin poured into the ends of large structural beams to both consolidate them and as an adhesive for the new timbers slotted into them.