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2 Answers

I live in Iowa and I want to know if it is necessary to have a vapor burrier on my ceiling if I have roof vents

I'm also considering installing an attic exhaust fan, not sure how to determine the size of fan I need.

In General questions | Asked By Chris | Sep 28 15
1 Answer

Detailing WRB/Roxul/siding in retrofit

I am putting together a plan for a client to add 2" rigid mineral wool as a continuous exterior insulation upgrade. One-story 1974 ranch house, huge 4' overhangs, zone 5 NW Ohio. Existing walls are 2x4 with fiberglass batts and interior poly vapor barrier. Current siding is vertical pine board-and-batten. Already encapsulated crawlspace and insulated foundation walls, air-sealed in attic and blew in more insulation, so doing the walls is Phase 3.

In Green building techniques | Asked By Andy Chappell-Dick | Sep 30 15
3 Answers

Crawlspace foundation with wing insulation as well as vertical exterior insulation?

Hi. In northern New York state, climate zone 6. Preparing to build a 20 x 30 second home for a client that will be insulated but not heated for the foreseeable future. Some day it might be used year round.

Crawlspace foundation with footings to frost depth. We are planning to insulate the stem walls on the exterior with 2" XPS. A slab is planned at level of footing. We are contemplating skipping the sub-slab insulation of 2" XPS and adding wing horizontal wing insulation instead--in addition to the vertical stem wall insulation.

In Energy efficiency and durability | Asked By Jon Brown | Oct 1 15
1 Answer

Polyiso along ceiling under truss chords

New build in climate zone 5. My plan is to establish my air barrier on the outside with zip sheathing and liquid flashing, and want to continue the air barrier across my ceiling (below a vented attic with blown cellulose). I thought about continuing the zip panels across the ceiling attached under the truss chords and tape them from the inside. I want to have options for drywall and tongue and groove wood for different rooms. I also thought about running polyiso boards in the same manner, maybe in two layers with staggered and taped seams. Any thoughts on this option?

In Energy efficiency and durability | Asked By Brian W | Oct 1 15
11 Answers

Exterior siding layers?

Hello all, I have a quick siding question.

When we spray foamed my shop with close cell spray foam we sprayed against the tyvek(housewrap). It was only one layer. It seemed like the best option we had at the time as I knew I would down the road drop the T-111 osb finished siding and replace it with plywood siding and housewrap and then a cement overlay (making faux stone work out of the cement)

In Building Code Questions | Asked By Max Anthony | Sep 27 15
1 Answer

Attic kneewall insulation

I have a raised heel truss system. The contractor installed wall sheathing up to the bottom of the truss 2x4 as shown in attachments. My overhang is 2' so I will have ~2' of soffit. I will vent according to the sq. footage of my ridge vent (hip roof). I am wondering if it is best to leave these gaps alone, at 3.5" tall or if I should put scraps up and make them closer to 2" tall, or if I should block the ones that will not line up with the vented soffit locations completely.


In General questions | Asked By Nicholas | Oct 3 15
1 Answer

Retrofit insulation


I've got a 150yr old big house back house type farmhouse in Maine. Even though there was some blown in cellulous in the ballon frame construction, it's cold in the winter (exterior walls feel very cold to the touch).

I'm debating between the following for adding to the interior side of exterior walls right up against the lath and plaster:

1. Putting up sheets of foam with drywall backing (how many inches is the best efficiency/cost choice)? Any caveats?

2. Putting up a two by four frame then filling with roxul insulation http://www.roxul.com/products/residential/products

In GBA Pro help | Asked By DJ | Oct 5 15
6 Answers

R-values - are they different depending on direction of heat flow?

I have a contractor claiming that their reflective insulation (alarm bells, I know!) has a different R-value for downward heat flow than upward heat flow. Is that possible?

The material is intended to be installed under the roof shingles. I spoke to the manufacturer and he assured me that the reflective property doesn't work when in contact with asphalt shingles, but that the product has an acceptable R-value for "downward heat flow" to be eligible.


In General questions | Asked By Whitney Larsen | Oct 5 15
14 Answers

Ceiling insulation

Have several questions.

1. I found a lot of rigid foam (2.5 inch) in the ceiling which is laid over the cellulose insulation. I thought that the moisture will be kept under the foam. Do I need to take off all the rigid foam? or just leave it?

In GBA Pro help | Asked By Ben Yoon | Sep 28 15
7 Answers

Vapor barrier on DIY walk-in cooler?

Hello, I need someone to answer a simple question for. I have searched the web and gotten conflicting answers.

I'm building a 15X20 walk-cooler that will be kept between 35-40 degrees F. This is for storing poultry eggs on a egg production farm in Milton Freewater, Oregon. (NE Oregon)

Three walls will be inside the larger barn structure, which will be kept between 60-80 degrees F, the fourth cooler wall is formed by the exterior barn wall, facing west.

The design completed so far is as follows;

In GBA Pro help | Asked By Mahlon | Oct 4 15
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