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6 Answers

Dense-Pack Cellulose Cathedral Ceiling

My roof (zone 3B) needs insulation, but between Martin's concerns and the inexperience of the contractors in this market, I am conceding that 5" of polyiso foam isn't going to happen. I think that 3.0" nail base (R15) can though (with taped seams). I'd like to get closer to the code minimum of R30 for the assembly. I would rather not tear out the finished interior vaulted ceiling (cedar shingles on battens on felt paper, I know, strange), but the lousy interior air barrier (i.e. the felt paper) concerns me.

Asked By Keith Richtman | Aug 14 14
1 Answer

Use regular OSB or Zip Wall OSB in conjunction with 2" XPS?

My wall plan consists of:
1- fiber cement siding
2- 3/4" air gap/ 1x4 firing strips
3- 15# felt (or possibly Tyvek housewrap) for general protection of the XPS
4- 2" rigid XPS with taped seams and caulked at butt joints
5- 7/16" OSB (possibly taped Zip Wall)
6- 2x4 24OC stud wall with mineral wool or fiberglass insulation
7- 1/2" drywall sealed at top and bottom and around device boxes and penetrations

Asked By Nathan Mogilski | May 22 15
4 Answers

Does this kneewall plan make sense?

I am in a 1915 Bungalow with sloping ceilings in each of four closets upstairs. I haven't demo'd yet, but I can guess what I'll find in terms of open joist cavities, etc.

My original plan was to demo the knee wall and spray foam the ceiling slope all the way down to the eave, but I just can't afford spray foam. So my tentative plan is to create an unconditioned kneewall area that can be used for storage.

Something about my plan seems a bit off, I'm wondering if I'm missing something big here.

I drew up a plan, I hope it shows up as an attachment.


Asked By Adam Sick | May 20 15
1 Answer

How to finish basement window

My windows have a frame with recessed sides and top. How do i finish, with drywall or wood?

Asked By John Kroeker | May 19 15
2 Answers

The "Perfect Wall" for Conversion Van in Warm/Humid Weather

After thinking about the "Perfect Wall" for an upcoming Van Conversion project, my goal is to use non-toxic, organic and sustainable materials. The base of the van is metal. As for layers I've considered the following starting from metal (inner layer) to floor (outer layer).

1. Lizard Skin Sound Control (Sound/Radiant Barrier)
2. Lizard Ceramic Insulation and/or PermaLoft Wool (Insulation)
3. Recycled Polyethylene (Moisture Barrier)

Asked By Sydney Jamila | May 18 15
3 Answers

How apply wallboard to sloping foil-faced polyiso?

In a Green Building Advisor discussion titled "Proper wall to attach rigid foam to the inside of the wall?" on Nov 17, 2014 asking about applying drywall on the interior side installed foil faced polyisocyanurate Martin Holladay responded:

Asked By Anthony Vogel | May 19 15
1 Answer

Superinsulated Slabs - Vapor Barrier

I'm designing a house for a site in Climate Zone 6B with high groundwater (~36-42" below existing grade during seasonal high water) and in an area of typically high radon. I've been exploring using a FPSF similar to what Alan Gibson described in his April 2010 article on Super-insulated foundations in JLC.

Asked By JMS Build | May 18 15
1 Answer

Why is there no plywood sheathing shown in your window installation construction details?

Hi all,

I was looking through the "How to Install Windows Right: Details for Leak-Free Windows and Siding" and didn't see plywood or OSB sheathing under the rigid foam sheathing in the drawings. What am I missing?

Thanks in advance,

Cecily Feudo

Asked By Cecily Feudo | May 12 15
10 Answers

Should I fill up unvented soffits with cellulose or block them off?

Hi all, I have a c. 1915 house with two gable vents. Until about a month ago, the attic had no access. I installed an access and have been busting my butt getting rid of the knob and tube wiring so that I can insulate. My ultimate goal is 18" of insulation, r-60 i believe. My climate zone is the zone four, but one county to the north is zone five.

Now, to my questions...

Asked By Adam Sick | May 8 15
14 Answers

Open cell spray foam on roof deck & vapor retarding primer


Asked By David Amenhauser | May 4 15
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