Rim board as headers.
Salibonz
| Posted in General Questions on
I appreciate any help and advice in advance. I have 2 questions
1) in zone 6a, is it a good or bad idea to frame a 2 story home with 2×4, diligent air seal and r10 continuous exterior insulation? Considering it is a spec home.
2) is it a good idea to use the rim joist for headers for all openings to add better insulation? Is it more or less costly as well? ( I guess 3 questions).
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Replies
Salibonz,
1) I don't see why not. The depth of foam does add some complications, but it yields a well performing wall. In other threads you expressed some concerns it would be difficult to market 2"x4' walls to buyers. I wonder how they would even know what the framing was?
2) & 3) It's simple to do. I suspect the cost is a wash. Framing the headers at the rim-joist is quicker and easier, but you do have to add hangers for the joists they support. Using them on a top storey only works if the roof is trussed with raised heels - and again necessitates the use of truss hangers, as well as altering the length of those trusses.
.Hey Malcolm, thanks for all your help. Yeah, I'm new in residential (been doing commercial), and I just want to be sure I'm not building a bad product. Most builders in my area do standard 2×6, I want to incorporate some green building techniques without breaking the bank. As far as altering trusses...why is that? I do plan on a raised heel for better insulation but on 2nd floor there wouldn't be a rim joist to beef up, it would be normal header placement I guess?
Salibonz,
When you add a header outside the truss heel above where the openings are, the trusses there - which usually span to the outside of the top plates - need to be shorter to accommodate it. The other alternative, which you can do both there and at the floor below, is run the beam (or doubled rim-joist) the whole length of the wall. That means you don't have to worry about where the openings below are, and would make moving them in the future a lot easier.
Hey Malcolm, if I add a double rim the whole length wouldn't that be more costly then to just beef the rim joist up at the window locations. I like the idea for better insulation but I also want to try and be cost effective. I appreciate your advice.
Salibonz,
Yes definitely more expensive. It's something I'd do for clients or myself.
You might look into using Zip-R sheathing. This gives you continuous external insulation but also provides you a wall that is fully sheathed with an OSB like material, which means installing doors and windows feels much more familiar than trying to work with details where the rigid insulation is outboard of the sheathing.
When looking at costs, it's important to look at the cost of the entire system, including labor. Don't just compare material costs of Zip-R and a sheet of OSB and conclude it's going to cost more.
I'm a big advocate of rim joists as headers. Malcolm told you all the important points.
Thanks jolly. The thing with zip r is it not enough to meet code if I do 2×4 framing and if I do 2×6 r factor of zip insulation won't keep the sheathing warm enough for the dew point causing condensation. Also zip is above $90 a sheet while zip sheathing is 32 + 45 for 2 inches of halo gps. I appreciate you input thank you