Repair Decayed Lower Jamb Joint

Wood repairs for sashes, frames and sills.
johnleeke
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Re: Repair Decayed Lower Jamb Joint

Postby johnleeke » March 6th, 2012, 5:19 pm

I guess how you orient the lap would depend on whether or not you are taking off the casing. Lap it in if you can take off the casing, lap it out if the casing is staying on. I've usually done these with the casing on, that's why I though of having the lap out.
John
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http://www.HistoricHomeWorks.com

oculus
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Re: Repair Decayed Lower Jamb Joint

Postby oculus » March 7th, 2012, 8:36 pm

Hey John,
Can you do a quick sketch as to what your repair looks like?
Thanks.
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

johnleeke
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Re: Repair Decayed Lower Jamb Joint

Postby johnleeke » March 8th, 2012, 10:01 am

Here you go.
Attachments
Jamb-Rot-2-LeekeLap.jpg
My way of splicing a new jamb joint with the lap facing out, so it can be made with the exterior casing left in place (although this sketch shows the casing removed). There is the lapped splice at the top of the new wood, and the dado of the joint with the sill at the bottom of the new wood. This is a partial splice, it only goes part way across the end of the jamb, as Amy has laid out the repair in her sketch. The top shoulder is beveled, so if the paint weathers off and the adhesive in the joint fails, water would tend to flow out of the joint--that's the traditional detail, in my view water might still enter the joint by capillary action. Sometimes I bevel these weathering joints, sometimes I don't, and have not noticed a difference in performance over the years. It is fun to do the bevel, but takes a bit of extra time and attention.
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

oculus
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Re: Repair Decayed Lower Jamb Joint

Postby oculus » March 8th, 2012, 10:41 am

I understand now what you are talking about. This repair would work quite well if you had to leave the casing on. Do you ever have problems getting the bottom dado to sit properly on the sill? Do you use adhesive in the dado? And add screws to the face?
How would you like the drawings to look for the standard? I would like the slope of the face cut be part of the standard. Out here where we get so much rain the slope of the face cut is critical. Also the fit must be pretty precise as well.
Since we are taking about only partial removal of the rotten jamb, how do you go about it if it is rotten all the way across? Same method? I will sketch up something of how I do it.
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

peter_carroll
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Re: Repair Decayed Lower Jamb Joint

Postby peter_carroll » March 8th, 2012, 12:53 pm

Great drawings John & Amy.

I try not to dutchman a unless the rot appears 1/2" or more past the sill. My method is to loosen the lower ext. casing & blind stop. (which by the way, is generally in the same condition as the jamb). I gently pick off the rot, dry out the space, harden the punk & apply a thickened, non-sagging, epoxy filler. (West, System Three, & ART have epoxies fitting these characteristics)

For a replacement, frankly I've tried all kinds of joints and most have gone over my budgeted time for the repair. I KISS or "less is best" this practice into the following for consideration: Warning! Very non-traditional.
1. Loosen or remove Ext casing. (for visualization/working room & ventilation)
2. Use a simple scarf joint (4:1 optimal/2:1 acceptable) in the Jamb bottom & again higher up on the blind stop. (I have found a butt joint effective in the jamb only & only if it is backed with a butt block of 2" wide X 1/2" thick X full length of joint) Oscillating Saw with fine cut blade & steady hands.
3. Rebate the end of the new jamb (no dado) to accept sill at the proper slope.
4. Apply thickened bonding epoxy to end grains of old & new Jamb/blind stop.
5. Glue & Screw or glue & clamp in place. Clean up access epoxy. (I use clamps & #6 x 3/4" brass wood screws, counter sunk & top filled) If the "fast" acting hardener the epoxy cooks off in 30 min cures in a day.
6. Re-set stop & casing, sand, caulk seams & finish.

I rely on the properties of the epoxy for bonding & waterproofing versus the joinery. Not traditional by any means, however the time for the repair is more predictable and less potential for over runs for the customer.

Longevity.......Don't know. Probably last for my life time & beyond. Technique is used in boat building often. I have a 8 yo wooden boat joined in this fashion that stays in the water or uncover (upside down) 365 days/year in Northern Michigan without any evidence of joints popping.

oculus
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Re: Repair Decayed Lower Jamb Joint

Postby oculus » March 8th, 2012, 1:49 pm

Hey Pete,
Thanks for keeping the discussion going on this topic!
Do you epoxy/fastener the rebate where the sill and jamb meet? Sometimes I try and get a screw into that area from the back but often the angle won't allow it so I then put a block or wedge of some kind in the weight pocket area. I have to make sure it doesn't interfere with the operation of the weights though. I just don't trust adhesive to hold it alone.
I will try and get a sketch up of all the techniques posted on this thread. I'll wait and see if anyone else proposes any more ideas.
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

johnleeke
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Re: Repair Decayed Lower Jamb Joint

Postby johnleeke » March 8th, 2012, 3:09 pm

Amy writes:
>>Do you ever have problems getting the bottom dado to sit properly on the sill? <<
No, the dado "clips" right onto the sill, but the the fit (distance between the dado shoulders) has to be a loose fit, much looser than when I make this joint all new when it is a "press fit."

>>Do you use adhesive in the dado?<<

Not if I'm making it an "open joint", so it can be taken apart in the future. I can usually fasten the dado joint with a long screw (3" to 4" or 5") angled into the joint from where the bottom surface of the sill meets the sheathing or siding of the wall. Before placing the new scarfed piece and the screw, I drill a shank hole from the bottom of the sill, angled up through sill and coming out the end of the sill.

>>And add screws to the face?<<

Yes, two shank holes through the new piece, spread the adhesive on the lap and shoulders, place the new piece, screw the new piece onto the face of the lap on the old jamb.

>>I would like the slope of the face cut be part of the standard.<<

I do too for the illustration. We might mention in the text that beveled is good for wet climates and unbeveled would be acceptable for temperate or arid climates.

>> Also the fit must be pretty precise as well.<<
A precise fit at the lap is good. A loose fit at the dado is sometimes necessary to get the new part into position.

>>Since we are taking about only partial removal of the rotten jamb, how do you go about it if it is rotten all the way across? Same method?<<
Same method, with the lap joint going all the way across the width of the jamb.

>>How would you like the drawings to look for the standard? <<

In this last sketch I just uploaded, I kinda like the combination of sketchy lines for the old wood, and ruled lines for the new cuts in the old wood and for the part made of new wood. You might refine the sketchy lines to single somewhat irregular lines. You don't need to get carried away with rendering on the surfaces. I would have repaired the end-checks before fastening in the new part, so you should probable delete the end-checks.

Let's let this stand for a few more days to see if the discussion develops further before you do the final on the drawing.

If no one else jumps in to write up and submit the standard for this one, I'll do it, but anyone who does this type of repair should feel free to do it. Most of the description and steps are all ready right here in the discussion.

This is looking to me like the ideal sort of "collaboration" this project is all about.
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

johnleeke
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Re: Repair Decayed Lower Jamb Joint

Postby johnleeke » March 8th, 2012, 3:14 pm

Peter:

For a replacement, frankly I've tried all kinds of joints and most have gone over my budgeted time for the repair. I KISS or "less is best" this practice into the following for consideration: Warning! Very non-traditional.
1. Loosen or remove Ext casing. (for visualization/working room & ventilation)
2. Use a simple scarf joint (4:1 optimal/2:1 acceptable) in the Jamb bottom & again higher up on the blind stop. (I have found a butt joint effective in the jamb only & only if it is backed with a butt block of 2" wide X 1/2" thick X full length of joint) Oscillating Saw with fine cut blade & steady hands.
3. Rebate the end of the new jamb (no dado) to accept sill at the proper slope.
4. Apply thickened bonding epoxy to end grains of old & new Jamb/blind stop.
5. Glue & Screw or glue & clamp in place. Clean up access epoxy. (I use clamps & #6 x 3/4" brass wood screws, counter sunk & top filled) If the "fast" acting hardener the epoxy cooks off in 30 min cures in a day.
6. Re-set stop & casing, sand, caulk seams & finish.


If you've been using this method for 10 or 20 years and know it works, go ahead and submit it for consideration.
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

Paul Marlowe
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Re: Repair Decayed Lower Jamb Joint

Postby Paul Marlowe » March 8th, 2012, 7:55 pm

Great discussion with interesting & detailed posts. Many years ago I took the path of repairing most of the exterior wood decay with epoxy & often in conjunction with borates as a preservative. In brief, the reasons would be that I feel when done properly these repairs can be mostly hidden & should last for decades with proper maintenance.

There are some issues to consider when introducing wood into this type of window jamb repair, especially if it is to be done with tight joinery & minimum epoxy or other type of adhesive or sealer. Wood species, heartwood, quatersawn, preserving & sealing vulnerable end grain, minmizing fasteners that are susceptible to corrosion are some items that should be considered. There are probably many times when dutchmen type exterior repairs are justified, especially if the wood is not going to be painted or coated with a solid stain & the texture or use of wood is specified for good reasons.

So as not to ramble on about a subject that might best be discussed elsewhere, I just thought I would mention my general approach & share these two photos. This window jamb is an 18th century reproduction. It is approx. 4x4 stock so the jamb & frame are one. The sash tracks are rabbeted, single hung sash, no parting bead, but I believe the exterior moulding was applied. The corners were pegged mortise & tenon joints & the decay was concentrated at the sill intersection as is common.
window trim & jamb rot prepared edited.jpg
window trim & jamb rot repair finish painted edited.jpg

oculus
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Joined: May 18th, 2011, 12:15 am

Re: Repair Decayed Lower Jamb Joint

Postby oculus » March 10th, 2012, 2:32 pm

Right now I have sketches of 4 different ways of doing this repair. All of them are excellent and valid ways of doing it. My question is how does the standard bring all these methods together and still remain coherent? Do some methods fall under contemporary and others under conservation? And how do we propose one type over the others when the different methods have been practised in such diverse locations? I have some repairs that see 17" of precip. in a year and others that see over 100" of precip. I guess you have to rely upon the knowledge and skill of the contractor doing the work. Knowing which methods will work best in what location.

I will post the sketches on Sunday. I am traveling for work today.
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


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