Gluing Sash Joints?

Wood repairs for sashes, frames and sills.
johnleeke
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Gluing Sash Joints?

Postby johnleeke » June 6th, 2011, 3:42 pm

This has been submitted for inclusion in the Standards:

After all the components of a sash are repaired or replaced, the sash is now ready to re-assemble. Connect the mortises and tenons on the four outside corners using epoxy adhesive. Install original wooden pegs. Place the sash is flat on a work table, square up and brace it until the epoxy dries. Only the corners should be glued. No muntins are glued together; they should be free to float within the frame.


This raises the question of whether or not sash joints should be glued. Traditionally, they never were, which is the important reason we can take them apart for repairs. If we glue them they cannot be taken apart for future repairs.

Glue may prevent moisture from migrating out of the joint, trapping moisture there leading to decay of the wood in the joint.

What do you think? Click on "post reply" below.
John
Standards Co-Founder
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http://www.HistoricHomeWorks.com

oculus
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Re: Gluing Sash Joints?

Postby oculus » June 8th, 2011, 3:05 pm

I don't glue any of my joints in the sash I repair or the sash that I build. The ability to disassemble the sash is crucial to the longevity of the sash. I work a lot with the SHPO here in Oregon and reversibility is a big issue with them. Epoxy is not very reversible in a mortise and tenon joint. I also teach my students never to glue the joints of the sash they are repairing.
Amy Harrington McAuley
Oculus Fine Carpentry, Inc.
http://oculuswindow.blogspot.com/
oculuswindow@gmail.com

"Opportunity is missed by most people because it is dressed in overalls and looks like work"-T.Edison

sschoberg
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Re: Gluing Sash Joints?

Postby sschoberg » June 12th, 2011, 3:29 pm

We have not glued any sash joinery. It just hasn't ever seemed appropriate. We certainly have seen lots of loose and/or hanging meeting rails however that is caused by defferred maintenance. I agree that if sash joiner was glued when made sashes would b e much much more difficult to repair. I say this based on our experience replacing individual parts of sashes. It seems that with the high quality of modern glues and epoxies if we glue sash joinery as we restore I'm afraid the sash would be doomed to much more complicated repairs in the future.

Steve S

peter_carroll
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Re: Gluing Sash Joints?

Postby peter_carroll » June 21st, 2011, 7:01 am

Our practice is to assemble the sash with a slightly larger dowel fit into a predrilled hole to a specified depth. We do use a slight amount of glue around the opening to hold the dowel in place. We rationalize a dowel can be easily re-drilled, however a glued joint will be a big problem.

Having said this, I will say the last two RFP's on historic buildings in W. Michigan specified for all sash joints to be epoxy glued.

Peter Carroll
Old Home Rehab

johnleeke
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Re: Gluing Sash Joints?

Postby johnleeke » June 21st, 2011, 9:30 am

Hi Peter, and welcome to the Forum.

I'm interested in the source of those two RFPs. Do they seem to be written from the same source? That is, do they use the same wording, or are they written by The same person, or from the same business or office?

Do you suspect the RFPs were written by someone with window experience, or by someone copying from a third party source?
John
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Standards Editor

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barnlover
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Re: Gluing Sash Joints?

Postby barnlover » July 8th, 2011, 3:54 pm

It had to be a 3rd party being influenced by the industry where epoxy is forever and who thinks about future repairs nowadays. I say never epoxy or glue any sash joints together. Your just creating a bigger problem for building and repairs for the future. Epoxy has its place and can be used but it also depends on the user.

bobyapp
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Re: Gluing Sash Joints?

Postby bobyapp » July 13th, 2011, 6:50 pm

Glueing mortise and tenon joints was never done traditionally. It wasn't so much much because of the ability to take them apart 100 years later (although that's a bonus), it had to do with contraction and expansion of the wood. Wood contracts and expands the most across its width and at the end grain. If a joint exposed to the weather is glued, it will cause splitting at the joints. The mortise and the tenon move in opposite directions. As such, if movemment isn't allowed to happen the wood in the tenon and the end of the mortised stile will split allowing moisture penetration.

A well fitting joint doesn't need glue anyway.

I'm not a fan of wood pins for the same reasons. I'm using two 1" x 3/32" stainless steel pins (stock from WW Granger) driven into the mortise and tenon at opposing angles. We set them an 1/8" below the surface and fill with linsead oil based glazing putty. We pre-drill the pin holes with a nail that is a bit smaller diameter so that when the ss pin is driven in, the fibers of the wood squeeze tighly around the pins. A drill bit would cut wood away while a nail bit plows through the wood fibers. These ss pins have nice flexibility and allow the mortise and tenon joint to move. We always pin from the interior side so that if the glazing ever failed in the set hole, excesive exterior moisture won't penetrate the joint. Wood pins are exposed on their end grain and are responsible for a lot of rotted sash.

sschoberg
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Re: Gluing Sash Joints?

Postby sschoberg » December 24th, 2011, 9:05 am

I'm not a fan of wood dowels either but we use them, more than the pins. But we try to stay as small as possible, so we don't do any more tenon damage than was done prior.

Were original dowels glued in place or were they more pressed in? I'm thinking no glue was used. As Bob says this not only allows for a bit of expansion. But also allows for a little movement of the sash if and when the house settles----along with the jamb, without damaging it.

We do not use stainless steel pins. Are they more slippery than plain steel? Do they move more with the expansion and contraction of the wood parts? What is your experience and history regarding this Bob? And when you replace the steel pins with the stainless how do you address the tenon repair? Not only the tenon replacements when needed but damage done from say a completely rust pins that deteriorates the hole through the tenon making it larger?

We do use many of the original pins though. If their rusted away we will use a dowel. Which bring on another question concerning damaged tenons. We repair most with epoxy, but sometimes the tenon is so bad a new one must be cut in. A floating tenon but glueing it into the rail seems ok. Lots of restorer judgement happen here at the tenons.

johnleeke
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Re: Gluing Sash Joints?

Postby johnleeke » December 24th, 2011, 12:40 pm

>>sometimes the tenon is so bad a new one must be cut in. A floating tenon but gluing it into the rail seems ok. <<

Steve, we need a standard on this repair method. Would be willing to submit your step-by-step procedure and a couple photos on it?
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

sschoberg
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Re: Gluing Sash Joints?

Postby sschoberg » December 24th, 2011, 2:56 pm

I do not have any previous pics for this procedure but I have an order to restore for some sashes now in the shop. The paint is off of them and they're ready for me to repair as soon as I complete this last storm window order.
I'm sure there will be a few of these dbl hung sashes that will need this procedure. They are rough. I will get to them and have some pics before the end of January.


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