My brother built a summer cabin on the eastern shore of Lake Ontario two years ago. The builder has lots of experience building here, but the structure has experienced shingle loss both last winter and this winter. The builder is going to replace the stapled-on 30 year shingles with a 50-year shingle, hopefully nailed on this time and with manufacturer-recommended high wind installation techniques. However, this winter something new has happened- the lake winds are so strong this year that the exterior wall that faces the lake is vibrating under wind load to the point that the drywall is cracking. The cabin has a gable end that faces west toward the lake and takes the full brunt of the winds coming off the lake. It has 2 large sliding doors and a semi-circular window high and centered on the wall. The roof structure is exposed heavy timber trusses with a cathedral ceiling; the walls are 2×6, full height of the wall, with T&G wood paneling over the lower 8′ and exposed, painted gyp board for the balance. There are no apparent issues with the exterior side of the wall. The first floor bears on a CMU foundation wall that does not appear to have a bond beam at the top. This wall is full height of the basement level and is also fully-exposed to the lake winds.
We just started kicking around some ideas of how to beef up the wall to eliminate the vibration. I also recommended to him that any fixes be run by a competent structural engineer before proceeding. One of the ideas I had was to strip the interior side of the wall. salvaging the T&G paneling if possible, remove the batt insulation and replace the gyp board with similar thickness OSB, glued and screwed to the studs. This will minimize issues with the door & window jamb/head extensions and give him a good nail base for the paneling. The cavities would then be filled with expanding foam insulation, essentially making one big SIPS panel out of the entire wall. This would increase the wall stiffness significantly and eliminate most of the wind-driven air leaks thru the insulation.
How about some feedback on this concept and possibly some alternate ways to address the problem? Thanks for the help.
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Is this resonance (a buzz or hum) or just banging in and out with the wind gusts?
If it's resonance then anything that changes the resonant frequency or disrupts the resonant "chamber" formed by the wall and adjacent structures (think of a massive whistle) will stop the noise.
This can be hedges or walls outside, adding weight to or removing weight from the wall, stiffening the wall, etc.
In fact, if you didn't have the problem previously but have it now I'd guess that some change was made that "tuned" the wall to resonance. Figure out what changed and go in the opposite direction.
bumpThis sounds like an interesting problem!Got any picts?
Yes, a photo or two would help
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<Got any picts?>
Here's one -
View Image
Forrest
Edited 1/1/2008 10:11 am by McDesign
Didn't I see you in one of the Harry Potter movies???:-D
Someone cut his hair quick! Those columns don't look any too strong to begin with.
If your view never changes you're following the wrong leader
"some change was made"The studs dried out and don't absorb shock as well, plus the dynamics of the fasteners connecting the surface material is different having less tension to the shrunk lumber
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This type wall would normally have had some attention from an engineer for wind load. Do you know if tht was the case here or if the builder just threw up what he thought would work?
Your idea might help but I would have it reviewed by an engineer.
Another way is that since this place also has exposed timmbering, he might be able to design a timber frame / pillaster application to apply to the interior of the wall without needing to tear it apart.
another - I have a picture on another PC if interested , is one I did like this where we built a sort of display shelf about 16" deep and 4-5 " tall so that it made a bulwark box across the span of the wall at 8' high. Trimed the face with crown and looked good with ships models etc displayed on it, but it was there to stabilize the wall. On yours it could be at the level wheere you transition from the paneling to the sheetroick.
Any builder who uses staples to shingle in a high wind zone oughta have his fingernails torn out - that is just plain insane
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WYB the basic construction and nailing schedual should be in question...
the stapled shingles are the give away...
more than likely the sheating is loose... no enough nailsd or they are too short...
or both...
would you suspect the sway and lateral bracing is missing???
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Yeah, that is why I asked about the engineering. I'll bet about three more studs and a few nails would have stopped this problem. He proably framed this 20' tall wall the same way he would have done a 8' wall and never considered how those large oppenings would introduce some bounce.It has sliding glass doors IIRC, but if they were regular swing patio doors, this would have been noticeable the first time they closed the door hard.A photo of it framed before getting closed up would say a lot!
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I'm not sure I have any photos, but I'll bet my brother does. My recollection of the International Residential Code, which I believe the New York State Building Code is based on, does not indicate the eastern shore of Lake Ontario as a high wind zone, but there may be some local requirements that would over-ride the basic code. Given the history of strong lake storms all along the lake, I would have to assume that engineered framing plans would be required to get a building permit. I'm going to have to dig into the history of this structure a bit more and get back to you, hopefully with some framing pictures.
I live in Tornado Alley and have some experience with strong winds. I also agree with the comment that a builder that uses staples in a high wind area ought to have his fingernails torn out. In this case, the manufacturer has some responsibility too. They sent out a rep last winter after the first failure and approved the installation! From first hand experience, I know it is possible to have a properly stapled shingle installation if everything is done near perfectly, but I wouldn't expect any roofer to be detail conscious as I am. It just isn't going to happen. I prefer nails anyway- they have a much larger surface area to resist pull-out, and all the manufacturers and building codes around here require it for all shingle roofs.
Just did some quick research:
1. The NY State Building Code is based on the IRC 2000. The basic design wind speed is 70 mph and, unless the local Building Official has declared a special High Wind Speed Condition with specific, higher design wind speeds, the 70 mph design requirements govern. This is normal stuff for framing; nothing special!
2. Last fall's initial shingle blow-off had 40-50 mph sustained winds, with higher gusts. The gusts were probably pushing the limits of the Design Wind Speed. I'm begining to suspect that more severe wind conditions have occurred this year and have exceeded the design requirements. I need to investigate further. The builder may be off the hook on this one if he built it to code &/or design drawings.
Edited 12/30/2007 10:14 pm ET by thedoktor
"My recollection of the International Residential Code, which I believe the New York State Building Code is based on, does not indicate the eastern shore of Lake Ontario as a high wind zone"LMAO here - I am sure the wind doesn't check the code to see if it is supposed to blow there or not! I have never built in a location that is on the map as a high wind zone AFAIK, but I know where the winds are high.I have been to that area and on a day with no storm going on, in the mildness of summer, had a hard time standing straight up in the wind. I can't believe that anybody building there for years would be unaware of how high winds can be coming off the lake! Let common sense trump the codes and remember that the code book is the MINIMUM required.
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Here's the latest: The walls are framed to 8' with 2x6's @ 16". It has a normal double top plate and the rest of the gable is framed the same way as the lower wall portion. At each sliding door jamb, there is a jack stud on each side of the opening supporting a 2x header with a 2x6 stud full height to the plates on the outside of the jack studs. These continue up to frame the opening of the semi-circular window centered between the 6' sliding doors. The normal cripples are above the headers. The load paths for the studs are pretty close to being continuous for the entire wall. Sheathing is 1/2" OSB with Tyvek & vinyl siding on the exterior. Take a look at the framing photos.
My brother reports that there is no apparent resonating of the wall- just bowing from the wind pressure. There are vertical cracks at both jambs of both sliding doors that appear to align with the rough opening.
I'm convinced that the wind load is much higher here than what the Code requires. The builder should have been well aware of this. I'm not sure that the drywall cracking can be stopped- only managed, given the size of the openings vs. the size of the entire wall. Drywall control joints with sealant will be needed, unless someone really likes fixing drywall cracks.
The double top plate acts as a beam of sorts, but obviously it's not enough. Stiffening of the wall is definitely required.
The wall is flexing rather than vibrating. I like Piffin's solution, create a shelf all the way across the wall at plate height. Make it so that it functions as a box beam and is tied into the side walls of the building. That wall should have been built with full height studs, and even then if the wind sped is high enough at that location they might well have had to have been LVL's on a very close center . One other option is to cut the plates out and install two floor to roof vertical tube steel columns, one each side of the upper window. Saddles can be welded to the columns to attach the plates to .
They can't get your Goat if you don't tell them where it is hidden.
The weak link is your top plate. Really should have balloon framed that wall. At this stage one solution would probably be a thrust beam run horizontally at or just above the plate. Unfortunately it's too late to incorporate it into the plate so it doesn't stick out so far.Another option would be knee braces of a fashion, from near the center of the top plate running diagonally to the walls on either side.(I'm assuming that this is an open ceiling.)
If your view never changes you're following the wrong leader
Is there a stud missing on the left side of the arched window ?I see a jack stud "under" the Header....where's the king.......
It is missing, but I don't think that is the cause of his problem.
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OK, Here is what I am seeing in this. First - it probably meets the minimum standards for framing there, but given the size of wall, the number of large opennings, and the wind load, I would have done several things differently.Here is what I see that makes it easy for wind to flex the wall - some of this is monday morning quarterbacking and some is basic stuff.First, the double top plate is not continuous. I see a joint right smack dab in the center. That location appears to me to be the joint between at least three pieces of OSB, so that it does not span that location to add strength. So right in the middle of the wall where flex can be greatest and wind load is greatest, the only thing resisting the flex is one 2x6 top plate.that point gets repeated several times when you consider that EVERY joint is a possible flex joint under lateral loading. That brings me to the second item - I always frame headers full height so there are none of the "typical" cripples above headers. In this wall, the mass also helps with absorbing vibrations. He does not feel vibrations perhaps, but if the wall can flex under wind there is vibration there.Third - keep in mind that the locations you mention seeing cracks in the drywall surface are locations where many sheetrockers find cracks later with NO loading on interior wall. It happens because of the header material shrinking when the sheetrock is fastened tight too close to the corner.There is a kingstud missing to the left of the arch-top window.I am at the other PC now and can find a couple photos for you. This place faces a NW wind coming across three miles of the bay here. Admittedly, it is used wind after your house gets done with it, but it can get pretty high too.;)In finding these photos, I am reminded too that I have a small awning roof along the exterior which probably serves to bolster things in adding resistance to the impact of the wind.Either idea could help add lateral strength to your place.
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Those were a couple of nice catches!. I'll bet the OSB is installed vertically too, rather than the recommended horizontal orientation. I agree that the framing appears to meet the minimum standards & I probably would have done it differently as well.
Your photos show a nicely done cabin & details. Both the awning roof and the interior shelf had to have stiffened up the wall, especially with all of the lower floor openings. Kudos!
Any time you are on a large body of water it is a high wind area. It just makes sense. But hindsight is 20/20.
It would be nice to put something outside to break up the wind before it hit the house but I can't think of anything that would work.
It would have a nice design to have that wall broken into two or three planes so the wind had less of a surface to push against.
I like the idea of a box beam across the whole wall. It would be a nice place to put stuff you don't want touched and you could light them with strip lighting.
Just had a thought. Wondering about the "shelf" on the outside, make a small roof that helped protect the entry doors as well. Depending on siding etc. it may be just as easy outside as inside.
They can't get your Goat if you don't tell them where it is hidden.
Thanks everyone for your insite & input. Hope everyone else out there can learn something useful from this problem. Just remember, as one of you mentioned, the Building Code requirements are just the minimum. Experience and common sense needs to be a part of the solution as well.
It would help brake up the area on the outside and shelter the doors. So it would accomplish three things. Good idea.
Shoot - I oughta get in the habit of reading all the posts and replies before I yump in!;)
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No problem at all. I do that all the time. You did a great job of summarizing it all though. I skipped the mention of the OSB install, and plate ends. Having a sheet of well nailed sheathing span that plate line would have done a lot for stiffness .
They can't get your Goat if you don't tell them where it is hidden.
"it would be nice to put something outside to break up the wind before it hit the house but I can't think of anything that would work."The awning roof I show in photo above or a pergola frame, which could also add strength and add shade to the porch area. since this is on the east shore of the lake, it faces west and must be an awfully hot situation sometimes in summer.
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