Second time homebuilder needs some advice from everyone–I’m going to post this under “energy, heating and insulation” as well.
First of all, has anyone used Obdkyke’s Homeslicker plus Typar? Do we know if that actually works? Is 1/4″ enough of an airspace to actually work as a rainscreen?
Secondly, I’m trying to make this home as tight and well insulated as possible. Want to completely eliminate thermal bridging. If I did NOT use that Homeslicker, my wall assembly would most likely look like:
2×6 studs,
1/2″ OSB,
Typar/tyvek,
1″ polyisocyanurate rigid foam insulation
1/2″x2″ (ripped treated plywood) vertical battens on the 16″ spiked into the studs
clapboard siding nailed into the battens on the 16″
So is this completely stupid? can you get away with only nailing off your clapboards every 16″?
If I did use the Obdyke product with no battens, can you get away with nailing off the siding with 8d ring shank nails through the rigid insulation or is there no way it would hold?
I read that one shouldn’t put the rigid insulation between the studs and the sheating because it compromises the shear strength of the nails. If one were to frame the wall but let into the studs a diagonal brace, then go ahead and sandwich the rigid insulation between the studs and sheathing, would that solve the problem?
What do you veterans think?
Replies
Just one note : around here we only use a rain screen on walls with exposure to high winds or minimal roof overhangs, often it's just one side of the house depending on the lot etc.
regards
Rik
UM,
First, I know nothing about Obdyke.
"I read that one shouldn't put the rigid insulation between the studs and the sheating because it compromises the shear strength of the nails. If one were to frame the wall but let into the studs a diagonal brace, then go ahead and sandwich the rigid insulation between the studs and sheathing, would that solve the problem?"
Would it solve WHICH problem?
Placing an effective thickness of insulation between the studs and the sheathing negates all its effectivness as a shear (anti-racking) membrane. If let-in diagonals are sufficient bracing for your area, you won't need sheathing as a shear membrane anyway. If they aren't, you need to figure another way.
Why not reverse the sheathing and insulation? Studs>>Sheathing>>Insulation>>Battens>>Drain Plane>>Siding.
You say 'rain screen' and I say 'drain plane.' I consider the siding to be the rain screen since it acts like bug screen. It only keeps the big stuff out, but lets air and water flow thru.
The components of your wall are as follows:
You could use a material that combines the functions of insulation and drain plane.
Depending on the decorative skin you use, it probably is sufficient in itself to provide the air and water flow needed to make the drain plane work and allow moisture to evaporate after a rain fall. If you did not caulk the heck out of the battens it could be fine without an 'air gap' behind it. Depends on how fast the siding itself has to dry out.
SamT
If you want to reduce thermobridging and also reduce air leakage why not use SIP's.
In many areas of NA, it is an urban myth that you need panel sheathing for shear strength. I haven't compared codes and don't know the extras needed in earthquake zones but in most of Canada, you only need a 1/2" DW on 16" OC studs to meet codes. If you have a "weak" wall with a lot of windows, it is reommended to use wood panel sheathing.
When you use 1x4 inlet bracing plus the 1/2" DW, you now have 1 item more than the code requires!!! The drywall adds a lot strength to a home's walls. I feel the 1x4 inlet brace + drywall is all you need unless the siding needs a solid base for random nailing such as in eastern white cedar shingles with 5" exposure. My 18 year old home has foam sheathing with 1x4 brace +DW. We went through a Category 2 hurricane (Juan) 2 years ago with no damage or extra DW cracks!!
If there's one area the code may be still a bit conservative in is the framing. Systems like "Optimum Value Engineered" framing reduce lumber use while building a good house with better energy conservation features- all for $$$ savings at the time of construction!!
This is exactly what I was after....Where do you live that you were allowed to let in the 1x4 brace? What kind of finish did you use and what did you attach it to?
the reason I wanted to both let in the diagonal brace AND use OSB over the insulation was to have as much nailing as possible for the clapboards. do you think that's overkill?