Articles on diagonal bracing and other lumber reduction ideas
joenorm
| Posted in General Questions on
Hello All,
I’d like to build a 20×20 enclosed shed in the next few months but I have the lumber price blues like everyone else.
Because it is a shed/garage I am more willing to experiment with ways to save. This will not be permitted.
The main way I can think to do this is to leave off plywood sheathing and brace the walls diagonally. Are there any resources out there detailing this procedure?
Are there any other ways to minimize material you-all can think of if you were building something without county regulations?
thanks for any ideas.
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Replies
Joe, this section of the IRC has a lot of relevant information: https://codes.iccsafe.org/content/IRC2015/chapter-6-wall-construction#IRC2015_Pt03_Ch06_SecR602.10.1. Even if you don't have to meet code, it's a good baseline for safe construction.
This article is an oldie, but goodie! Produced by the Forest Products Laboratory in the late 70's.
To summarize, it has all the math and models needed to made decisions on let-in bracing.
https://www.fpl.fs.fed.us/documnts/fplrp/fplrp301.pdf
Diagonal bracing- let-in wood bracing, or steel bracing - works very well, and particularly for a shed/garage would be a great idea. I've built two of my homes with both methods and can attest to its quality. Done correctly it willmoffer every bit of diagonal strength your structure requires. Another big cost savings is rough-sawn lumber. At least in my neighborhood the cost of rough-sawn has not followed that of dimensional lumber, and remains considerably more affordable, although more labor is required because of the inconsistencies in dimension that can vary considerably depending on the sawyer.
Daniel,
It depends entirely on what shear resistance the structure requires. There is a sliding scale of effectiveness starting from having the walls designed as shear-panels with mechanical hold downs connected them to what is above and below, to relying on the moment connections of the framing alone, with diagonal bracing somewhere in the middle.
As I recall Joe is in the PNW where diagonal bracing may or may not be enough, although for non-residential structures it would probably meet code. I'm doing much the same thing with two shops I'm building right now, using let-in bracing on both the walls and roof, but I have no illusions on how they will fare in a significant seismic event.
Let in braces used to be lots more common, and are still one of the prescribed ways to brace a wall allowed by code as far as I know. You would use diagonal 1x4s for this.
If you want to be creative with your structure to save on materials costs, be aware that even if you're not pemitting the structure, you do still have a very real safety issue if it fails. If you're going to stray too far from the normal code-approved building methods, you should really have an engineer review your plans prior to building. In today's lumber market, the engineer will probably be cheaper than the extra lumber so you'll still come out ahead, but you won't have to worry about your structure collapsing on you in a windstorm.
Bill
Thanks Bill,
While I am trying to get creative I don't intend to build an unsafe structure. But I think we can all admit we often have a tendency to overbuild. My family has a 100+ year old barn built on wood rounds with no form of diagonal wall bracing, and skip sheathing on the roof. While yes, it looks it's age, it is still a useful utility space that has never been a hazard to anyone.
Joe,
I d0n't think that's true at all. While wood frame buildings are often not engineered to within an inch of their life they way more technologically refined products are, the redundancy in their structure is what makes the method so resilient over time. The benchmark surely isn't whether they are hazards or not.
Agreed. All I was just getting at is there are multiple ways to do things. Simpson brackets and plywood is not the only way.
One benefit of sheathing is that it makes for a decent critter barrier, depending on how persistent wild life is, you might need it.
If you decide to skip the sheathing, one budget siding option that I've done that also is great at keeping critters out is nailing up vertical galvanized sheets. After nailed up, roll it with a color of your choice (make sure to use the right primer for galvanized) than cover the nails and seams with battens for a pretty traditional board and batten look. If you go with fiber cement or composite battens, it will be very durable. Without any sheathing behind and nailed on 16 OC, you'll probably get some oil canning.
Besides the benefit of keeping critters out, the nailed up sheets will make a huge difference in strength and add a lot of extra bracing to the structure.
I'll second the critter barrier aspect. Having built two homes without any plywood or osb may have saved me money, but it cost me in the additional labor - a lot of time, effort and energy to seal things up against unwanted intruders that plywood would have been a simple and effective solution to.
Doesn't siding keep critters out?
One thing that hasn't been mentioned is that your square length width ratio and small footprint makes an inherently strong shape unless you have a bunch of large door openings. My thought would be that with diagonal bracing and good hold downs is that you'll have a sturdy building. You could always add interior sheathing down the road if lumber prices fall. Or you could use tongue and groove boards to sheathe the inside wall, which is a classic look.
Hi,
Simpson has metal coil straps that are listed for wall bracing - the product is RCWB Rolled Coiled Wall Bracing. If you plan to sheetrock the inside then it is code approved for bracing, if nailed correctly. The IRC prescriptive guidelines have many ways to brace a building.
I think a 20x02 is more than the 120 sf that is exempt from the code
Joe,
You might want to read this article I wrote on the topic: "Four Options for Shear Bracing Foam-Sheathed Walls."
Another relevant article is "Wall Sheathing Options."
Pole barn.