*
I have seen and am considering using a wall construction system that I’d like other’s opinions on. Let me try to describe it:
There is a foam core to which 2X3’s are laid flat on either side and long screws go through the 2X3 on one side, through the foam and into the 2X3 on the others. The ends of the 2X3’s are flush with the top and the bottom of the foam core. Each “panel” is then toe-nailed thru the 2X3’s to the sill, and a top plate is added, nailing down through into top of the 2X3’s. The gaps between the foam cores are filled with a can of spray foam.
Any obvious flaws?
Replies
*
Why are ther3e gaps between foam cores?
How thick is the foam?
What size are the plates?
*This sounds like prefabricated foam panels.You cannot make them at home.
*What is the intended result? Sounds kinda shakey, like a lot of work to accomplish what? Why 2x3? Every time I see 2x3s they look like crap, kinda like tomato stakes. Joe H
*Piffin: There are gaps between the foam panels because I can buy them only in 4'X8' panels (maybe 4X12) so every 4 feet there will be a gap (perhaps I should say seam?).George: The foam panels are prefabricated (we have an outlet nearby for seconds and so can buy them pretty cheap). The walls themselves *can* be made at home, I've seen a 28'X40' 1.5 story addition made with this construction. Joe:The intended result is a wall with a thermal break that is cheaper than SIP's. Higher efficiency and all that. As to why 2X3's, I think the answer is that when screwed together like this they may not be as strong as a solid 2X6, they're probably stronger than a 2X4, so... why not? :-)
*Sounds goofy, buttttt, how are you going to space the 2x3s? Use 2x4s and put them at the joint and secure them with your foam adhesive. What kind of screws are you planning to use? Screws aren't free either, all this cheap might add up to wasn't so cheap after all. What kind of foam is it, what is it made for and why are the panels seconds? Joe H
*Piffin: There are gaps between the foam panels because I can buy them only in 4'X8' panels (maybe 4X12) so every 4 feet there will be a gap (perhaps I should say seam?).George: The foam panels are prefabricated (we have an outlet nearby for seconds and so can buy them pretty cheap). The walls themselves *can* be made at home, I've seen a 28'X40' 1.5 story addition made with this construction. Joe:The intended result is a wall with a thermal break that is cheaper than SIP's. Higher efficiency and all that. As to why 2X3's, I think the answer is that when screwed together like this they may not be as strong as a solid 2X6, they're probably stronger than a 2X4, so... why not? :-)
*The building I saw had the 2X3's 16 inches on center. The joints were all in the middle between 2 studs. In other words, on a 4' panel, the 2X3's were centered at 8, 24, and 40 inches.You're right about the screws. The ones used are the ones used to secure decking over foam on roofs. For the building I mentioned earlier, I think the screw bill was about $250.The foam comes from a foam insulation outlet (so called) and is either truly seconds (which are great if you have to cut around things anyway), or they come from distressed situations, usually when an insurance company paid for a total loss (but the foam wasn't really damaged - as in a warehouse fire) or from inventory liquidations. For this application, I would be steering away from the true seconds.
*Sounds a little goofy to me too - but where would America be if it werren't for innovators trying and then trying again. If you've seen it and it's your money.......I'd rather spend it on a two x four wall and add an inch of foam to the inside for thermal break. But it ain't my house.As to the gaps, I stillldon't see a need to have any fitting the panels snugly together behind 2x3s. Save the foam for the damaged seconds repairs.
*piffin:I appreciate the endorsement :-). I have thought of the 2X4 with foam laid on the outside too. Have questions about where that will put the effective dewpoint/condensation point. Don't want no rotting in the walls.As for the gap - it is really small, 1/16" - 1/8" is about usual as it looked to me, but worth foaming as it would be in the method you suggest.
*John, have you bought a copy of Joe Lstbreck's book that matches your climate? Lot of details that would help you I think. Not necessarily with this particular question, but the overall project. Taunton Press, find the book section here & pick one of the three. How much is a 4x8x2" of this foam? Joe H
*Notice I said foam on the INside, NOT OUTside.When Thermax was first marketed it was to place on the inside over fibreglas, this was in the seventies when energy was a big thing and when the 2x6 @24" walls got started. A 2x4 wall with fibreglas and foam was showen to be more efficient than 2x6 with fibreglas only, parly 'cause of the thermal break and draft stop.
*Joe:4X8X4" (not 2") is $27.50
*
I have seen and am considering using a wall construction system that I'd like other's opinions on. Let me try to describe it:
There is a foam core to which 2X3's are laid flat on either side and long screws go through the 2X3 on one side, through the foam and into the 2X3 on the others. The ends of the 2X3's are flush with the top and the bottom of the foam core. Each "panel" is then toe-nailed thru the 2X3's to the sill, and a top plate is added, nailing down through into top of the 2X3's. The gaps between the foam cores are filled with a can of spray foam.
Any obvious flaws?