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KinAlberta
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# Posted: 5 Jul 2018 13:59 - Edited by: KinAlberta
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Right now this is all just me trying to think through the issues of siding several buildings at the lake and creating much stronger longer lasting structures at the same time. The nice thing about this site is that members will step up and critique my hair-brained thinking. 
I would guess that normally putting metal sheet siding on buildings built on blocks might not be generally recommended because walls can flex or sag. However, I’m hopeful that I could use it as a means to actually stiffen entire walls of buildings on blocks.
Since I’d like to put metal siding on three plywood sheathed outbuildings in the future I am thinking I should do a few things first to dramatically boost the stiffness of the walls. (The buildings are all 1970s constructions: an old 7x14 boathouse on beams and blocks on surface, 16x22 boathouse on beams and blocks on surface of the ground, 22x24 garage package sitting on cinder blocks dug a bit into the ground without any beams and just a dirt floor). Since the ground freezes evenly for all the buildings frost heaving has never occurred, however they each have settled slightly at different points but mostly towards on or more corners.
Right now, none of the buildings are perfectly level, I hope to level them all up, beef up the beams where I can and then likely overlap a new layer of plywood over the old painted plywood sheathing.
Where possible I want to turn walls into double 4’ tall* or single 8’ tall ‘beams’ the length and width of the buildings where no doors exist.
I initially thought a building wrap would be the way to go and then screw the metal to the wall. However, I’m now thinking maybe I could put spots or strips of glue or silicone or something somewhat flexible on to basically laminate the metal to the wood to further stiffen the walls.
So either way, the metal siding itself should also serve to stiffen the walls to reduce risk of sag.
In doing this though, I’d be transmitting more stress to the corners and I’m not sure of what consequences this could create.
* the garage package has staggered 4x8 sheathing installed horizontally. So I’m thinking of screwing, nailing and gluing on either one or two more layers of plywood on their sides as well.
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snobdds
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# Posted: 5 Jul 2018 14:21
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Just use some closed cell spray foam. It provides additional racking strength by 75%, as the manufacturer claims. It does a fantastic job of creating rigidity at very low weight.
Not cheap, but it is fast and very long lasting.
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KinAlberta
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# Posted: 5 Jul 2018 16:19 - Edited by: KinAlberta
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That’s really interesting.
Thanks.
The reason I am thinking that adding more plywood is based on the comment below.
So while plywood is only half or less the strength of a 2x__
(1 1/2â€x_) can go well beyond a 2x12†or 2x14†in terms of depth with 4’ layer of plywood and have a good surface for screws. However just running a 2x12 along the plate and lower sheathing and then 2x4s or something as furing might work better as I could just run 16’ boards rather than doing the sheet lamination thing with plywood.
Basically 50%
“three 2x12s offer 48% more bending resistance than three 2x10s.â€
http://www.finehomebuilding.com/1995/01/01/using-plywood-in-built-up-beams
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snobdds
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# Posted: 5 Jul 2018 17:23 - Edited by: snobdds
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https://www.whysprayfoam.org/builders/building-strength/
Your adding a lot of weight to prevent the weight sag problems in the first place.
I don't know if you can tell, but I love spray foam. Next to GRK screws, it's the best construction advancement in the last 20 years. It's amazing how much it does for a building.
Insulation
Vapor barrier
Increases racking strenght
Thermal break
Noise control
I don't know if you have paid attention to how an expensive car sounds when a door is shut, but you get that same solid feedback in a spray foam enclosure.
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ICC
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# Posted: 5 Jul 2018 22:47
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Quoting: KinAlberta spots or strips of glue or silicone or something somewhat flexible on to basically laminate the metal to the wood to further stiffen the walls.
You are trying to remedy a foundation problem with band aids. Construction adhesives creep when shear forces are applied... seen it happen. Those glues are good at preventing floor squeaks and are a good easy way to attach decorative panels but not so great for structural use.
Silicone is very flexible. It will not increase shear strength or increase rigidity.
Some metal panels are rated for structural use. Most are not.
Closed cell foam sprayed into stud bays can increase rigidity, make a wall more resistant to racking. Must be closed cell foam, the type that cures hard.
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ICC
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# Posted: 5 Jul 2018 23:20 - Edited by: ICC
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Do a search on stressed skin panel or stressed skin construction. You might find something there that will help. Or search shear wall construction
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KinAlberta
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# Posted: 6 Jul 2018 22:52 - Edited by: KinAlberta
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I wouldn’t say they are foundation problems that need to be remedied but I would guess that in order to use metal panelling a stiffer wall would be better than not. The buildings are all currently doing very well considering they sit on blocks. They all flex a bit and if re-leveled would be fine for several more decades. Doors and everything work fine too. However, if I can stiffen the structure, spread the load more evenly then there will be fewer pressure points and less potential sag and less risk to metal paneling. Screwing through the metal into the studs would also likely lock them pretty well into place.
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ICC
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# Posted: 7 Jul 2018 10:13
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Why not install some more supports/piers/blocks? Make the beams better supported and the walls will not be able to sag.
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KinAlberta
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# Posted: 8 Jul 2018 16:27 - Edited by: KinAlberta
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That's a great point and I can do that with our boathouse.
The garage though is already supported every few feet by cinderblocks (wrongly set flat side up). It also sits in a poor often wet location which gets the runoff from a couple different directions depending on whether it’s snow melt or rain. So it looks like the wall has sunk by maybe 1/2†or so in a couple places and I can see a bit of stress/separation in a couple points in the old sheathing. My thinking is that like a dry cardboard box vs a wet cardboard box, strong walls would spread load over soft points. The 2x4 stud walk sits on a 2x4 plate on top of a 2x6 I believe. Basically only 3†of 2x on the flat. It’s the sheathing that is currently keeping the wall as horizontally straight as it is.
Maybe a better analogy than the structural rigidity of a cardboard box would be the floating effect of snowshoes or tracked vehicles vs tires. Spread the load broadly and evenly and it floats on the surface. Whereas tires and boots and walls without beams or walls that can’t act like beams* themselves would concentrate weight and sink.
Putting in piles would always be a wonderful solution but the costs quickly add up and possibly hit again in taxes. I don’t think our small 7x14 boathouse on skids is even taxed.
* aka: stressed skin, insulated panel, torsion box, unibody vs body on frame...
Interesting old article:
STRESSED-SKIN PANEL PERFORMANCE
AFTER
TWENTY- FIVE YEARS
OF SERVICE
By OTTO C. HEYER, Engineer, and R. F. BLOMQUIST1, Chemist
FOREST PRODUCTS LABORATORY 2
U. S. DEPARTMENT OF AGRICULTURE, FOREST SERVICE
https://www.fpl.fs.fed.us/documnts/fplrp/fplrp18.pdf
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