The current issue of Fine Homebuilding carries an article comparing OSB with plywood. I wanted to ask for opinions on sheathing with old fashioned T&G board sheathing. I know it’s old tech but I’d be curious to hear pros and cons from forum members. Has anyone studied the comparative installed strength versus OSB/plywood sheathing? What about horizontal installation of board sheathing versus angled?
A second but related question. I’ve worked around the chemical industry a lot over the years and have a very healthy respect for chemicals and the effects of exposure to them. Does anyone know of recent studies (hopefully by relatively unbiased parties) about offgassing from products such as OSB, plywood and engineered wood products? Homes are literally full of these products today. Somewhere between the manufacturers and the environmental groups must lie the real story. The trouble I often find in the chemical industry is that the compounds are often too new to have any long term data available. As a result, we become the test cases for future studies. My usual approach with chemicals is to minimise exposure to them if I can. For example, I recently put up a building using board sheathing. More work, but my weekend labour rate is pretty cheap.
I realise that modern construction with tight schedules and cost controls influence material choices and construction practices but I just wanted to ask the pros for their thoughts. Thanks.
Replies
I'm concerned about off gases.
That didn't stop me from building with osb and plywood.
I drink more than 2 cups of coffee each day too. I like living on the edge.
blue
Just because you can, doesn't mean you should!
Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!
Coffee drinking reduces the odds of getting liver cancer.
Installing diagonal sheathing increases the labor costs of closing a frame.
Most of the diagonal sheathing I've replaced the siding on was utility grade (#3) doug fir, was riddled with loose knots or empty knotholes....a little problematic at times when the occasional siding nail blew through a F/C plank and rattled to the bottom of a stud cavity.
Diagonal sheathing greatly increases the shear strength of the wall.
Diagonal sheathing greatly increases the shear strength of the wall.
...in comparison to horizonally placed 1x's.
I believe the Notch was referencing a comparison with osb/plywood sheet goods which at a minimum equals the diagonal layout of 1x's.
be board"Live Free, not Die"
Diagonal sheating has proven longevity - lots of old buildings sheathed this way are still standing. Plywood is a post-WW2 building technology, OSB was introduced in the '70s iirc.
An alternative is gypsum board sheathing. Better fire resistance than wood products, also.
I'm pretty sure studies have been done on off-gassing. For a while, lots of products had formaldehyde in them and that was a problem. My understanding is that this is less of a problem now. You may try looking on the web for studies. There's a place that does lots of research, something like "Forest Products lab" or similar (can't remember exact nemae) that may have info. Maybe even Consumer Reports. If you were very concerned. you could provice a breathing space between sheathing and siding using vertical furring to allow some ventilation.
I just read the article today on the comparison between the two products and found it interesting. I do not think that you have to worry too much about the off-gasing from plywood and OSB. The biggest culprits are the VOC's and chemicals such as urea-formaldehyde which is used in the glues in particle board (e.g. kitchen cabinets and IKEA furniture!!). There are some places in the world however, that are quickly addressing Indoor Air Quality issues and countries like Japan are now requiring that all framing components with glue (e.g. OSB and plywood) that are in the conditioned space (the building envelope) of a building get tested by a Japanese agency. Some people call this protectionism but others call it progressive?
I also wanted to make the point that I thought FHB was a bit slanted in their comparison of the three products (OSB, plywood and the "new generation" OSB such as Advantech). It seemed to me that they were promoting the new generation OSB as being the superior product and I found this suspcious given the amount of ads I see for Advantech in FHB.
Nothing suspicious about this. Before they did the article, they came to this forum for comments and suggestions and they were overwhelmend with the number of responses from those of us who use, recommend, and admire the Huber Advantech products. All you have to do is to use it once and you'll be a true believer too. It beats OSB or plywood hands down.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
pg... i wouldn't use osb on a bad bet..
but i'll use Advantech until the cows come home.. used to be just for sub-floor..
but from now on, with our 110 mph windload requirements, we'll also be using the Advantech 5/8 t&g for all of our roof sheathing..
and ...... for sidewall , i'll be using either Advantech or 1/2" plwood , whichever is less $
and.... i make those choices based on quality... not price..
i think FHB is basing their Advantech push on their reader's pull....
builders who've used Advantech , that prefer a quality product, won't use anything else
but, hey, whadda i no ?
Mike Smith Rhode Island : Design / Build / Repair / Restore
I've worked on a lot of floor systems with OSB and I've never noticed any problems. I have been told however, that some flooring manufactures won't warrant their wood floor products over OSB, so that IS a problem.
I've only used advantech a few time, myself personally, and find it to be a nice product, but I'm not sure why I would choose it over OSB if I'm not putting a wood floor on it.
As far as sidewalls, I'm totally happy with ANYTHING.
Roofs...I hate clips and I think that Mikes 5/8" t&g would actually be faster than installing clips. I'm not sure I would want the 5/8" advantech up there on the roof, so I'd probably opt for "regular" osb. Buttttttt, since the t and g is a lot more cash than clips, I'd probably opt for the clips for my own house. I'm all for pinching pennies where ever possible and I really don't get that entrhalled looking at overbuilt roof sheathing...after all it all get covered up with layers of leaking tarpaper and shingles anyways.
blueJust because you can, doesn't mean you should!
Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!
Mike,We never, ever, ever use regular OSB for our panels we ship around the world. We also rarely sell OSB subfloor and never sell OSB roof sheathing. We have used Advantech or like product (e.g. Norboard, Grant Flooring) when available. The only problem for me is getting Advantech in my neck of the woods. We are big proponents of plywood Spruce on the wall and Fir on the roof. Advantech is a superior product but it is over priced!
The off gassing issue is an old one. Few products contain the offending chemicals anymore. When you use board sheathing there are a couple things to consider. Horizontal boarding is not very strong laterally. Many areas will require diagonal bracing with this choice. Going diagonal with the boards is more work and takes a 45° cut on each end. A horizontal boards spans 16" centers 14 1/2". On a 45 it is more like 20", not very strong especially on floors. It was widely done this way last century because that's what they had. The diagonal placement aided in later installation of hardwood flooring, which could be placed in either direction in individual rooms. Boards shrink and sometimes take the other materials attached to them along for the ride. The resulting gaps let in air and heat loss. Windows and doors come made for 4 9/16" thick walls or 6 9/16". They don't quite make it with board sheathing.
Most of the builders in my area use Advantech on the floors, 7/16" OSB for sheathing and 5/8" CDX for roof sheathing. They are all excellent products and do the job they are intended to do when installed correctly. Far superior to #3 boarding or we'd all still be using it. You are more likely to have gas problems with cheap carpet or imported upholstered furniture. Super tight houses may cut energy consumption but they can be very unhealthy without proper air exchange. It has more to do with what you do and put in the house than the products it's built from.