Sash seals - on the sash rails not the frame

[rich1911]

Any advise on putting draft seals on sash windows?

I don't like brush seals, so I'm looking at Q-lon.

There are many types to choose from, so not 100% sure which are the best to use. Looking at various drawings online, flipper type seals seem common.

I'd like to have them on the sash rails themselves rather than on the parting beads and staff beads etc. Is there any reason not to do that?

This type of arrangement shows a different type of seal to the flipper one:

And this drawing uses the flipper seals:


Maybe both work fine and there's no 'right' way?

Cheers!

 

[Jacob]

Don't put them between meeting rails nor along the bottom rail. These are routes for condensation to drain out and will cause problems if sealed. Also the slot for the seal itself becomes a water trap. The tiny bit of draught resulting is good for the window and for the room itself.

 

[Ollie78]

Reddiseals have a good range.

I use the brushes because there is 3 sizes and this allows for adjustment in old and twisted boxes where 2mm either way can be the difference between them moving or not.
I prefer to use the self adhesive carrier rather than the slot in method, to prevent this being a problem I paint everything before putting the carrier in.
I do put draughtproofing in meeting rail and bottom rail, there is always a bit you can't seal at each corner anyway. To remove moisture from condensation etc the windows need to be opened for 10 minutes in the morning.

Why do you not want to put the seal in the bead ?
The reason not to put seals between the edge of the sash and the pulley lining is that it doesn't take much expansion to wedge it tight. If your box and sash are not perfectly square it can be a nightmare. I have had to rectify many windows made this way.
Sash windows like a bit of float side to side, not loads but some.
I like the 2 part plastic parting beads, great for future maintenance no decorating required.

Ollie

 

[Doug71]

I don't make that many sash windows but like you I am not keen on brush seals on show, they always get grubby or painted.

I tend to use Aquamac 21 in the sash stiles similar to your bottom drawing.

I keep thinking of trying this stuff from Coastal but haven't got around to it yet, it means taking quite a bit out of the edges of the sashes but looks like it would make a good job of sealing the sash and helping it slide.

https://www.coastal-group.com/Twin-Blade-Sliding-Sash-Seal-96m-Coil-Black?quantity=1&size=461

 

[owen]

I don't see what's wrong with having seals on the parting and staff beads personally, you hardly notice them if they're fitted right. Also it seems like a lot of messing about with the sash especially if you have to plane it down to fit, and end up having to re-router the groove deeper. I agree with Jacob I wouldn't bother on the meeting rails, a wedge shape on either meeting rail seals the gap pretty well anyway.

 

[Doug71]

Some people split the parting bead in the middle of the window so the brush seal is hidden behind the sashes in the closed position and you only see it when the sash is open.

 

[Ollie78]

Some people split the parting bead in the middle of the window so the brush seal is hidden behind the sashes in the closed position and you only see it when the sash is open.

This is how I do it.

You can use the Qlon type seals in the 8mm 2 part plastic parting beads and also in the staff beads with appropriate channel if you dislike the brushes.

Ollie

 

[RobinBHM]

I've designed a sliding sash which is fraught sealed with aquamac 21.

It goes on the stiles on the edge - near the inside and outside.

If you get the position correct, it acts as guide for side to side and front to back....the secret is to set the groove position so the aquamac is proud by a couple of mms.

I was a bit sceptical because aquamac 21 is designed as a compression seal not a sliding seal, but it works fine. I intend to ring schelegel and ask if they've tested it for that application.



The problem you will have is getting plain staff and parting beads without the draught seal groove

 

[owen]

Some people split the parting bead in the middle of the window so the brush seal is hidden behind the sashes in the closed position and you only see it when the sash is open.

Thats how you have to do it, it wouldn't work otherwise, unless you have double sided parting beads

 

[rich1911]

Thanks chaps. Lots to think on there.

I hate the brush seals we already have. They were poorly fitted so maybe thats whats making me biased!

One of the main reasons for upgrading the windows is not just for draft proofing and better insulation but I want to cut road noise as much as possible too. I figured good all round seals would do that. (not as good a triple glazing but...)

Our house is very exposed and we are only a few miles inland from the coast, so we get some serious weather. At the moment I tape up the windows and have acrylic secondary sheets over the windows! (Yes it looks really classy!) I don't think there's too much risk of lack of ventilation... Sometimes the wind can blow the secondary glazing sheets off!

I am planning to replace the sashes completely, hence why I was looking at fitting the seals to them. It's no problem to run a groove around the sashes to fit seals.

 

[LBCarpentry]

I see weights in your drawings...

but have you considered......

spring balances??
(I’m enjoying watching your journey into the world of window making btw)

 

[rich1911]

I see weights in your drawings...

but have you considered......

spring balances??
(I’m enjoying watching your journey into the world of window making btw)

I had a few windows made with spring balances. Have to say I'm not impressed. They look tacky and seem to be unreliable.

If I can save my frames, I hope to be able to use lead weights to handle the DGU's.

(Glad you're enjoying the journey too!)

Just getting the joints clear in my head before making a decision on where and what seals to use!
(my sketchup drawings)

 

[Ollie78]

I see weights in your drawings...

but have you considered......

spring balances??
(I’m enjoying watching your journey into the world of window making btw)

I trust this is a joke.

Please do not consider the spring balance.

Rich1911

The solution to noise is acoustic laminate glass like Stadip. The first time I did some sliding sashes with acoustic double glazed units I couldn't believe how effective it was.
Worth the extra few quid per unit every time if noise is your concern.
Bear in mind the thinnest stadip is 6.4mm so this extra thickness must be taken into account.

I still think you should just make your sashes the regular way round.


Ollie

 

[rich1911]

I trust this is a joke.

Please do not consider the spring balance.

Rich1911

The solution to noise is acoustic laminate glass like Stadip. The first time I did some sliding sashes with acoustic double glazed units I couldn't believe how effective it was.
Worth the extra few quid per unit every time if noise is your concern.
Bear in mind the thinnest stadip is 6.4mm so this extra thickness must be taken into account.

I still think you should just make your sashes the regular way round.


Ollie

Hi Ollie, have no fear, I won't be using spring balances!

I'll look into Stadip, not heard of that. Thanks.

So 'regular way round' is fitting the glazing from the outside? Is having the beading exposed to weather a good idea?

All the windows in our Orangery were done like that, but the examples I posted above both do it the other way around, beading inside.

Cheers.

 

[RobinBHM]

So 'regular way round' is fitting the glazing from the outside? Is having the beading exposed to weather a good idea?

industry do it both ways, there is no right or wrong way

internal beading risks leaks if the glass is not sealed properly

external beading risks leaks and potential issues with glazing bead pins, shrinkage and movement of the glazing bead.

Ive had quite a bit of feedback paint reps, joinery consultants etc in the industry and different manufacturers try different methods. Success depends more on the detailing and employees following the corrrect procedures than the method used.

A recent method is to have a small rebate in the glazing bead that goes up against the glass -and after window is glazed the rebate is filled with hybrid paintable silicone. It is even possible to get a special bow pinner to put in pins through the rebate to hold the bead, avoiding any brad heads that need filling and exposed to weather.

 

[rich1911]

I don't make that many sash windows but like you I am not keen on brush seals on show, they always get grubby or painted.

I tend to use Aquamac 21 in the sash stiles similar to your bottom drawing.

I keep thinking of trying this stuff from Coastal but haven't got around to it yet, it means taking quite a bit out of the edges of the sashes but looks like it would make a good job of sealing the sash and helping it slide.

https://www.coastal-group.com/Twin-Blade-Sliding-Sash-Seal-96m-Coil-Black?quantity=1&size=461

Sorry Doug, only just found this.

These look like a great idea! A seal in the corner to support the sash in both directions.

Thanks for posting.

 

[Ollie78]

Hi Ollie, have no fear, I won't be using spring balances!

I'll look into Stadip, not heard of that. Thanks.

So 'regular way round' is fitting the glazing from the outside? Is having the beading exposed to weather a good idea?

All the windows in our Orangery were done like that, but the examples I posted above both do it the other way around, beading inside.

Cheers.

Traditionally windows are made with a scribed joint, so the moulding of the stiles sit perfectly in the opposing shape cut onto the end of the rail on one side of the tenon. This is a very tight fit and provides good glue surface area.
This is particular fun when doing a large Georgian sashes with 10 panes or more.
Not to mention curved ones....

There is nothing "wrong "with doing it the other way exactly. It is one way of accommodating double glazed units with a higher sightline as a deeper rebate on the inside can be hidden with a bigger bead. Not much good on anything with glazing bars though.
To me it just looks weird to see the inside bead, especially if it's extra big. Like some I have replaced.

Stadip is the sgg brand name, there are competing brands but I forgot the name of them. If you fit the laminate inside and toughened softcoat on the outside it looks best.

I don't use a bead on the outside.
I face the window to look exactly like a traditional putty but use a hybrid polymer which is paintable, stays slightly flexible and seals the entire unit in. This way a unit failure is extremely unlikely.
Do it after priming but before topcoat, then it is indistinguishable from putty.

Those corner seals bother me slightly, it won't take much movement to pinch them tight. I suggest ok for nice new accoya boxes and sashes but I would hesitate to put them in an old box with any twist.

Ollie

 

[rich1911]

Traditionally windows are made with a scribed joint, so the moulding of the stiles sit perfectly in the opposing shape cut onto the end of the rail on one side of the tenon. This is a very tight fit and provides good glue surface area.
This is particular fun when doing a large Georgian sashes with 10 panes or more.
Not to mention curved ones....

There is nothing "wrong "with doing it the other way exactly. It is one way of accommodating double glazed units with a higher sightline as a deeper rebate on the inside can be hidden with a bigger bead. Not much good on anything with glazing bars though.
To me it just looks weird to see the inside bead, especially if it's extra big. Like some I have replaced.

Stadip is the sgg brand name, there are competing brands but I forgot the name of them. If you fit the laminate inside and toughened softcoat on the outside it looks best.

I don't use a bead on the outside.
I face the window to look exactly like a traditional putty but use a hybrid polymer which is paintable, stays slightly flexible and seals the entire unit in. This way a unit failure is extremely unlikely.
Do it after priming but before topcoat, then it is indistinguishable from putty.

Those corner seals bother me slightly, it won't take much movement to pinch them tight. I suggest ok for nice new accoya boxes and sashes but I would hesitate to put them in an old box with any twist.

Ollie

Thanks Ollie,

Lucky for me, I don't need to do Georgian windows, just simple sashes. Big, but just simple sashes.

The first window I will do is pretty straight forward. Small and it has a good frame. The bays are going to be the hardest as they are not square any more, the centre frames have dropped slightly and the sides are therefore out of square.

These also need a lot of repair work on the frames, or replacement.

There's a lot of weight on them from above too.

What's the 'normal' clearance on sash and frame? 2mm all round, assuming I have a square true frame? (The seals can handle up to 5mm is some cases.)

Here's what I need to replace eventually! This is one side, there's another exactly the same next to it.

All the woodwork at the top needs looking at too.

The top frames are probably OK, the lower frames have old scarf joint repairs in and a lot of rot.

 

[RobinBHM]

Sorry Doug, only just found this.

These look like a great idea! A seal in the corner to support the sash in both directions.

Thanks for posting.

View attachment 103190

I recently prototyped a box sash window using aquamac 21 as per this drawing.

It works very well and It's now what we do.

The problem with the furry stuff is it gets mouldy and dirty