LD1
Epic Contributor
That is like those trusses I was talking about that had angle iron tops and bottoms with round bar in between. (or sometimes little angle iron in between.)
OSB or Plywood for Truss Gussets?
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That is like those trusses I was talking about that had angle iron tops and bottoms with round bar in between. (or sometimes little angle iron in between.)
LD1
Epic Contributor
All this talk of OSB and trusses had me thinking about a crazy idea, that would probably never work anyway....
And would only be cost effective on larger trusses that use heavier members, like 2x8's and up......
Why not build a truss like the OSB I-joists? No ope webbing, rather all closed in with OSB and 2x4 around perimeters?
Of course not having open webs would be a drawback... But something like 6 sheets of OSB for a 4/12 pitch 40' span truss. That ~$60 and about $40 of 2x4's around the perimeter. I would "think" that would be as strong as one of them large OC spaced trusses that has 2x10 tops and 2x8 bottoms. Cause those trusses are ~$300 or so to buy?
I know its a crazy idea, but I am bored.....what the heck. (I am not actually going to build trusses like this).
I am sure the first time someone had the notion to make the i-joist people called him crazy...
And would only be cost effective on larger trusses that use heavier members, like 2x8's and up......
Why not build a truss like the OSB I-joists? No ope webbing, rather all closed in with OSB and 2x4 around perimeters?
Of course not having open webs would be a drawback... But something like 6 sheets of OSB for a 4/12 pitch 40' span truss. That ~$60 and about $40 of 2x4's around the perimeter. I would "think" that would be as strong as one of them large OC spaced trusses that has 2x10 tops and 2x8 bottoms. Cause those trusses are ~$300 or so to buy?
I know its a crazy idea, but I am bored.....what the heck. (I am not actually going to build trusses like this).
I am sure the first time someone had the notion to make the i-joist people called him crazy...
6sunset6
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A note about glue
I have built 5 buildings with field built trusses, the last one a monster 34' span trusses on 8ft centers ibeam rail for hoist suspended on centerline. That structure has been up for 20 years with lots of hoist activity.
Glue yellow ,white are not structural. glue line creeps under load. Construction adhesives the same. There were 2 structural waterproof glues, epoxy and the two part resoursanol . Rsoursanol is no longer available due to emissions. Epoxy is expensive. The one that still works structural, water resistant is the urea type. Indoor use only . Brown powder that you mix with water. The nails provide clamping pressure. I use plywood and over size the gussets to increase the glue area. All that said I would just buy trusses next time.
one other note I build a parallel chord truss bridge , 34' , , for the Appalachian trail, used the urea glue (indoor use only ha) . We just took the bridge down 2 years ago . It was up for 25 years and still had some life left although sagging a bit. Previously Hurricane Irene flooded the area , brought down a hugh tree which lifted the structure off its supports and sent it down stream, in one piece. Flood subsided some, we went swimming and floated it back up steam, jacked it up and winched it back into position. I can vouch for urea glue.
I have built 5 buildings with field built trusses, the last one a monster 34' span trusses on 8ft centers ibeam rail for hoist suspended on centerline. That structure has been up for 20 years with lots of hoist activity.
Glue yellow ,white are not structural. glue line creeps under load. Construction adhesives the same. There were 2 structural waterproof glues, epoxy and the two part resoursanol . Rsoursanol is no longer available due to emissions. Epoxy is expensive. The one that still works structural, water resistant is the urea type. Indoor use only . Brown powder that you mix with water. The nails provide clamping pressure. I use plywood and over size the gussets to increase the glue area. All that said I would just buy trusses next time.
one other note I build a parallel chord truss bridge , 34' , , for the Appalachian trail, used the urea glue (indoor use only ha) . We just took the bridge down 2 years ago . It was up for 25 years and still had some life left although sagging a bit. Previously Hurricane Irene flooded the area , brought down a hugh tree which lifted the structure off its supports and sent it down stream, in one piece. Flood subsided some, we went swimming and floated it back up steam, jacked it up and winched it back into position. I can vouch for urea glue.
Capricious
Platinum Member
That's the Weldwood "Plastic Resin" glue that i mentioned in post #34.
Supposedly it is not considered waterproof because the glue bond will fail in boiling water.
I have used it in boatbuilding although my preference is to use epoxy (which will get soft in boiling water as well.)
Epoxy is not as expensive as it used to be, as long as you avoid Gougeon Brothers ("West"). I have used epoxy from (2) discount suppliers in Florida:
This outfit used to be about the cheapest, last time i checked:
Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc.
This guy was a little more expensive, but had the advantage of having "slow" and "fast" hardeners that could be mixed to taylor the "set-up" times to suit the ambient temperature and the particular job:
Raka, Inc. 772-489-4070
Second guy also had a "cold weather" hardener that i used for winter work (does not harden "clear")
EDITED TO ADD; If i was building the subject trusses, I would use a marine-grade fir plywood (or something that looked as good- many layers of veneer, few voids), bolt the connections, and use the Weldwood glue which is cheap and easy to use, but requires temps of 70 F or above in order to harden (If it were winter I would have to re-think the glue).
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Egon
Epic Contributor
If you are worried about glues stay clear of modern airplanes.
Think the Mosquito used a Resorcinal type glue and plywood.
Think the Mosquito used a Resorcinal type glue and plywood.
/pine
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FWIW...Resorcinol glue is still available...from many places even amazon
Amazon.com: Aerodux Resorcinol Resin Kit - 1 Gallon Bottle: Industrial & Scientific
Amazon.com: Aerodux Resorcinol Resin Kit - 1 Gallon Bottle: Industrial & Scientific
SPIKER
Elite Member
Never really checked this issue out that well, we build trusses on site for my barn. They were built and done for about 3 weeks before the crew made it back. They were stapled and PL400 glued, on both sides with 1/2" Solid Core plywood. They were flipped after being glued and nailed on one side and none of them gave any when being flipped. They used 1.5" x 1/2" staples I think they were 18gauge on the other side & to fill in between the nails. The exterior staples used on the T1-11 didn't hold all that well & had some edge pull issuse. The roof seems good with no issues after 13 years.
They DID have one problem when they laid out the gambrel truss design & was off 1/2" from side to side (so there was a left/right problem) so some they flipped upside down and others spun over so the lefts and rights got messed up some which made some up/down un evenness on the roof but no biggie.
(EDIT IN)
I went back after the roof was on and cut 2x6s and filled in the outer sections that were spanned with plywood only used PL400 in the opening and hammered the 2x6 cut to fit into opening and added nails. This was done to have a nailing surface on that angled part when or if I ever get it finished.
As far as WET OSB there are different glue grades as well, I have some section of that floor that is wet peel up a bit but not bad. Some cut off sections of that floor material has been laying off the edge of the slab for 2 years now & just last few months been soft enough to feel it give when stepping on it.
As for Glue and the Waxy side you actually would want to use the rough side for the glue to stick to. Like attics you will actually see the WAXY side INSIDE when laid correctly & the outside shingles/tar paper will be stuck to the dry/rough side.
Mark
They DID have one problem when they laid out the gambrel truss design & was off 1/2" from side to side (so there was a left/right problem) so some they flipped upside down and others spun over so the lefts and rights got messed up some which made some up/down un evenness on the roof but no biggie.
(EDIT IN)
I went back after the roof was on and cut 2x6s and filled in the outer sections that were spanned with plywood only used PL400 in the opening and hammered the 2x6 cut to fit into opening and added nails. This was done to have a nailing surface on that angled part when or if I ever get it finished.
As far as WET OSB there are different glue grades as well, I have some section of that floor that is wet peel up a bit but not bad. Some cut off sections of that floor material has been laying off the edge of the slab for 2 years now & just last few months been soft enough to feel it give when stepping on it.
As for Glue and the Waxy side you actually would want to use the rough side for the glue to stick to. Like attics you will actually see the WAXY side INSIDE when laid correctly & the outside shingles/tar paper will be stuck to the dry/rough side.
Mark
sld
Veteran Member
The only reason you even see OSB is because it's cheaper and easier to work worth. Quality plywood is stronger in every way than OSB. Emphasis on quality. The multiple layers of crossing grains make it very strong in shear and compression.