air barrier for loft ledger (pic of 20x30)

[JeffnTN]

John, I am having trouble finding a previous post using the search feature.  It had to do with using Tyvek as an air barrier at the ledger for the loft on the 20x30.  Can you repost this?

Thanks for all your help!

Jeff

[John Raabe]

I'm not sure which post this might have been.

If you want a better than normal air barrier you could use a strip of Tyvek (or poly) behind the ledger to carry an air barrier to the wall surfaces above and below. Just lap over the studs above and below.

Otherwise, an air barrier on the exterior of the wall would normally cover this area as well and cut down the airflow.

[JeffnTN]

Thanks, John.

I have the entire exterior wrapped and taped with tyvek.  I just want a really well sealed home.

I originally planned to sheetrock before installing the loft floor but the sheetrock guy talked me out of this.   Less $$$ for me to pay if he has the loft to work off of even though mine is only 12 ft of the 32 ft length.

Without being able to fully mud and tape all those seams (at the loft/beam joint) due to the loft floor being installed first, would you use poly or tyvek and tyvek tape for this barrier?   Both, maybe?

I have plenty of both left over.... No additional $ in materials and  my labor is cheap...just my timeLOL,

thanks, Jeff

[John Raabe]

If the ledgers are already up I wouldn't worry about it as the exterior Tyvek is a good barrier. If not, then put a strip behind it as I noted above as you put it up. This is extra protection for airflow control.

[JeffnTN]

John, Thanks for the help.   I will prob just not worry further.  I guess it will be ok.


I just want this to be the best I ever built since it is the first  (and probably the only) one I have/will build for myself.   Helped build many for others but this is my first.  Thanks again for the great designs.  It was a great help to have a starting point like that.

I will try again to post a recent pic (yesterday) of the cabin in the snow.  Tried yesterday but did it not work...

OK it worked this time.  Thanks again everyone for the input.

[John Raabe]

Nice Job Jeff! Looks good.

Also, on your airsealing, since it sounds like the ledgers are up, you can caulk the drywall or wall covering to the ledger after the fact. In fact, wait until the house has dried out pretty well (but before any trim). A little extra airsealing makes a difference in a cold climate. Also, caulk the wiring and plumbing holes in the plates. Check with the electrical inspector for the right caulk for the wires. Latex is OK for the other airsealing.

[JeffnTN]

Uh Oh.  I already used Great Stuff expanding  foam to seal the MANY oversize holes  that the electrician driiled through the plates.

i did not event think that might be a problem.  It should be ok, should`nt it?  I sure hope so.

Jeff

[JeffnTN]

no inspection here....   no meter since I am hooked up to a previously inspected meter/service on an existing building.....

[John Raabe]

Maybe you can get a better reply from an electrician, but the main requirement of the sealing is air blockage (both from an energy and fire spread point of view). For that the foam you have used is fine.

I wouldn't be concerned that some code jurisdiction might have a tighter specification on the type of foam.

Here is a report on air sealing Habitat homes in Washington DC. They specify a "red fire rated foam". http://www.greenhome.org/pdf/opcaulk.pdf

[JeffnTN]

I called dow Chem. the mfr of the foam.... they are saying it is ok as long as it is "code"...  that is yankee talk for insulated wires ;;;LOL


They are worried about fire damage and lawsuits as that stuff is VERY flammable during application and curing.  I sprayed it into/around the gaping holes left by the elec when  the wires were not  hot and killed the panel just to be sure.

[CTBuilder]

Actually, what you should be using is fire barrier caulking.  It turns rock hard when dry and prevents fire from running up through holes drilled through plates. Anything to keep a fire from slowly running up the walls saves lives and structures.

Randy