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16 Answers

The differences between mass and insulation

The "I installed more attic insulation and now my AC runs more" thread got me thinking about the mass effect a bit.

Asked By Nathaniel G | Sep 15 14
0 Answers

Trying to determine best assembly to insulate an old church roof being converted to office

We are looking to keep the existing roof decking and rafters exposed in a church in Atlanta, Climate Zone 3. We have read Martin Holladay's FHB Article about unvented, Super Insulated Roofs, and Joe LUtiburek's article BSI-036 Complex 3D Air Flows talking about the subject. One of the big differences (really somewhat minor) I see between the two recommended details is the best place to locate the fully adhered air barrier. Martin shows placing it at the outermost layer right on top of the new sheathing, right below the roofing material. In this case asphalt shingles.

Asked By Eric Kronberg | Sep 16 14
4 Answers

Air sealing question: Assistance requested for 6th side of building envelope

My husband and I are homeowners who are working on a very deep energy retrofit of our 1860's house, almost a total rebuild. We have learned so much from this website and the Q's and A's from everyone's contributions, so many thanks to all readers and contributors. We had already started the building process when we learned of this site, and are now attempting to make accommodations for deficits in our education and processes during the early stages of our build.

Asked By Howard Lederman | Sep 14 14
1 Answer

Sill slope? Sealant tape?

How much slope is recommended for window sills? The house isn't in an coastal or otherwise very exposed location, but isn't in an arid or especially sheltered place either.

I'm planning on using beveled siding, placed on a flat plywood window buck, to help move water away from the opening; the exterior face of the window frame will be set about 4 - 5" back from the outside of the exterior sheathing. I'm trying to figure out how much extra room (vertically) to include in the rough opening.

Asked By Graham Fisher | Sep 16 14
13 Answers

Retrofit heating system

We recently bought a second home in the Catskills, which was built in the 1930s. Current heat system is oil furnace forced air with a pretty new high end furnace. We had an energy audit done and found that the house was not well insulated at all and are in the process of takin advantage of energy efficiency programs to upgrade.

Asked By Carole Florman | Sep 15 14
4 Answers

Out-sulation vs Double Stud Walls

I was reading some old GBA discussions about double-stud wall designs and the added difficulty of keeping the sheathing dry (relative to wall designs that place appropriate amounts of insulation over the sheathing). This prompts me to wonder why the double-stud approach has its adherents when an out-sulation approach can be used to achieve the similar R-values and protect against thermal bridging while dispensing with the uncertainty regarding moisture. Besides being of general interest to me, I am hoping the responses will help me decide the 'best' way to proceed for a future project.

Asked By Rob Shuman | Sep 16 14
1 Answer

Effectiveness of roxul "flash and batt" - irregular ccSPF causing air gaps

I have a spray foam crew coming Thursday to convert my attic to "unvented" (2x8 rafters). They want customers to do 5". My plan though was to do 4" and then 3.5" roxul batts to fill followed by a layer of the roxul board to reduce bridging on the rafters. I've spent way too much time researching and cannot find anything decisive on this. Specifically the question is about the air gaps that would be present between the ccSPF and the roxul. I've seen this question come up several times in comments here, but it's never addressed.

Asked By Chuck Swanberg | Sep 16 14
16 Answers

Liability insurance - what would that cover?

1. Does liability insurance cover issues related to removing improperly installed open-cell foam in an attic on the underside of a roof (i.e. all those horror stories about roof rot, or open-cell continually off-gassing or smelling weeks after it was installed, etc..)? Or is that a different type of insurance?

2. Should I specifically ask for the details in the Liability insurance to find out specifically what it covers, is that something contractors should be willing to share?

Asked By George G | Sep 12 14
6 Answers

Raising a sunken floor

I am planning on leveling an 18” deep sunken living room (15 ft x 15 ft ) with the surrounding area and then install travertine flooring. To save some concrete, I am planning on using EPS to fill the first 14” of the sunken room and then poor a 4" thick concrete slab. I read an answer to a similar situation posted a few years ago that lead me to believe that the concrete slab my not be needed, and that I could possibly install plywood or hardy baker board on top of the foam with foam compatible adhesive.

Asked By Andres Ferro | Sep 5 14
1 Answer

Insulating and air-sealing a room-in-truss over a garage

Hello,
I am looking for some clarification on insulation and air-sealing, when dealing with room-in-truss construction for a conditioned space over a garage.
I live in Michigan, climate zone 5. I have a 28x36 garage, with 28ft span 8/12pitch "attic" trusses. the trusses have a 2x10 bottom chord and 2x8 top chords with 2x4's at the kneewall. I have a permanent stairwell going to the room in the truss, and I plan to heat the room. I have in-slab hydronic heating on the garage floor.

Asked By Ben Helmreich | Sep 15 14
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