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casement window (buckled wood sill)

casement window (buckled wood sill)

casement window (buckled wood sill)

(OP)
The wood sill of the metal casement window shown in the attached photos is buckled upward. I am not correlating the buckling with foundation movement. The window crank is operational and the window opens and closes with ease and its arm slides beneath the buckled wood sill with ease.

Here is what I think the problem is; please chime in with comments.....

Changes in temperature and humidity cause the wooden sill at the bottom of the window to expand and contract. Loosely-applied sealant strips fell out of the window when the window was opened. The sealant strips were recently applied to this 25+ year old window. This is an indication that air/water is and has been intruding through the vertical edge of the window, eventually making its way to the wooden sill. Over time, the constant thermal movement has caused the wood to buckle upwards. The house is located in the northeastern portion of the U.S. Proper window sealing s essential to keep moisture away from the sills.

Thanks for comments.

RE: casement window (buckled wood sill)

Is the sill rotten as well? If so, then I would tend to agree with you. Otherwise I'm not so sure. I have a hard time believing the studs are so stiff and the sill was cut so tight that it couldn't swell longitudinally without buckling.

RE: casement window (buckled wood sill)

What time of year did the buckle occur?
Is the window protected by a soffit, or on an exposed gable?
Are the window ext. frame seams intact?
Is it possible water could the assy. and form an ice pocket under the sill?
in the picture showing the splintered woos what is the item shown inside the crack?

Temps and humidity change do not produce this kind of damage.

RE: casement window (buckled wood sill)

The split wood looks fairly dry in the picture. I would suspect an awful lot of moisture would have to get into the wood to force it to expand that much. Doesn't appear to be the case here. Looks to me like forceful damage...maybe someone tried to break in through the window?

I have a few wood framed windows in my house around the same age....when the wind blows, the curtains move. I intend to replace them as soon as possible. The damaged sill is just another reason to replace the window.

RE: casement window (buckled wood sill)

From the Wood Handbook 2010

"Longitudinal Shrinkage
Longitudinal shrinkage of wood (shrinkage parallel to the grain) is generally quite small. Average values for shrinkage from green to ovendry are between 0.1% and 0.2% for most species of wood. However, certain types of wood exhibit excessive longitudinal shrinkage, and these should be avoided in uses where longitudinal stability is important. Reaction wood, whether compression wood in softwoods or tension wood in hardwoods, tends to shrink excessively parallel to the grain. Wood from near the center of trees (juvenile wood) of some species also shrinks excessively lengthwise. Reaction wood and juvenile wood can shrink 2% from green to ovendry. Wood with cross grain exhibits increased shrinkage along the longitudinal axis of the piece.
Reaction wood exhibiting excessive longitudinal shrinkage can occur in the same board with normal wood. The presence of this type of wood, as well as cross grain, can cause serious warping, such as bow, crook, or twist, and cross breaks can develop in the zones of high shrinkage."

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

RE: casement window (buckled wood sill)

Quote (CanPro)

The split wood looks fairly dry in the picture. I would suspect an awful lot of moisture would have to get into the wood to force it to expand that much. Doesn't appear to be the case here. Looks to me like forceful damage...maybe someone tried to break in through the window?

My suspicion as well.

Looks like a pry job - What does the outside look like? Dry wood, sharp break at the middle of the casement. No surface mildow or discoloration, no signs of damage along the casement at the window sill.

If it were caused by expansion of the lower casement, you'd have to see both ends of the casement forced into the lower casement. If pried up from the middle, the lower casement would be pulled away from the vertical ends.

RE: casement window (buckled wood sill)

From the first picture it doesn't look like someone tried to force their way in, I think a pry bar would have damaged the finish more.

Was anyone up on the roof above the window recently?

I have seen similar damage from framers neglecting to put in trimmers for the header, and a cripple below the window pushing in the frame after it crushed a rotten sill. Attached is what we found when we peeled the wall apart.

RE: casement window (buckled wood sill)

This does not look like a moisture issue. I've seen plenty of those and this is not one.

I believe the mechanical actuator arm buckled upward and split the wood. Open the window fully and you'll likely see that one side or the other does not open all the way, or if this is a single swing casement, then compare its opening to an undamaged window.

It is likely that a retaining clip for the actuator arm is broken, allowing the arm to lift upward during actuation.

RE: casement window (buckled wood sill)

Ron has the most likely solution now that I think about it.

RE: casement window (buckled wood sill)

PSUengineer1:
Do you have any more or better pictures of the broken/buckled area? I can’t see that area very well or in enough detail. The broken piece is really a fairly thin, routed-out wooden piece, a trim piece, at the sill, of the entire finished window frame, a cover piece for the operating mechanism, isn’t it? I don’t have any casement windows handy to look at, and there are several minor variations on how that mechanism works and is housed in the finished frame of the window. I think I can see part of the operating mechanism under the broken piece of wood. I’d want to very carefully take the broken piece out, to see what’s going on, and to repair it, glue it back together, and replace it, reinstall it. If the window works fine, and all the margins and reveals around it are uniform and square, I would discount much structural movement. You’ll have to look around the entire sash and finished window frame for signs of moisture intrusion. They should show staining, etc. Clad sash can break at the corners and seams and can take on water, but that doesn’t look to be the case here. You might be able to open the wall below the window, behind the sink, to see if there is any moisture evidence there. The seals and caulking may be missing or failed, and should be fixed. I’ll bet the window was locked or jambed some way, and that someone over-did-it on the crank to try to open the window, and that this caused the mechanism to buckle upward and break the thin wooden piece.

RE: casement window (buckled wood sill)

Which direction does the window face? I have seen one larger window actually bow out and break due to heat from sun shining on that area. Could there be a chance for water within the sash verticals that expanded under that heat and created a vertical compression load in the vertical parts? With the sun now at a lower elevation in the sky, is there more exposure to sun than in summer?

RE: casement window (buckled wood sill)

Ron:
This looks like the great minds thing, again. smile

RE: casement window (buckled wood sill)

dhengr....thinking like me could be dangerous!! lol

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