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8 Answers

Cement board "slab" on grade

Hello GBA folks,

I'm in the process of designing a house in zone 7/8 and would like your feedback on this design idea.

Instead of a concrete slab on grade, glue 2 layers of cement board, such as 1/4" Hardie board to each other and to 3 or 4 inches of EPS foam. Offset each layer to avoid matching seams. Prepare the bed with crusher fines and perhaps sand to get level and compacted surface for the foam. This might be difficult? Add a vapor barrier below the foam. Finish floor with tile, carpet (glue tack strips to cement board), etc, but I'd like to use cork.

In Green building techniques | Asked By Mike | Jan 19 16
7 Answers

1980s house with tri-level partial walls, in an attic in Swansea, Massachusetts

A little history. I live in a tri level home in southern Massachusetts built sometime in the early 80's. Been in it about 12 years now as the 3rd owner. It's been added onto by previous owners and part of the old roof over the main floor was partially left on and built over (a story for another time. I have several walls in my home that run from the basement into the main floor attic. I became aware of home performance a few years ago and very interested in improving this hard to heat in winter and hard to cool in summer home.

In Energy efficiency and durability | Asked By Michael | Jan 20 16
5 Answers

Rigid foam sheathing moisture accumulation

I would like to add 2" of exterior rigid foam to a 2x6 wall in climate zone 6. This is a new build. After reading your article "Calculating Minimum Thickness of Rigid Foam Sheathing" it sounds like with only 2 inches I am risking moisture accumulation behind the rigid foam. I've seen that Dupont offers a "Tyvek Drain Wrap" material specifically designed to go behind exterior rigid foam that allegedly allows any condensation behind the foam to drain. Does anybody have any experience with this particular material?

In GBA Pro help | Asked By David | Jan 20 16
1 Answer

Roxul in the attic-vapor barrier?

I'm thinking of replacing the old fiberglass insulation in my attic. I'd like to use roxul but was wondering about the vapor barrier. Can I simply remove the old insulation and lay the vapor barrier over the ceiling joist and friction fit the roxul over the plastic? What thickness vapor barrier should I use? I live in zone 6A.


In General questions | Asked By mike terry | Jan 20 16
3 Answers

Vinyl siding over 2" foam, no strapping?

I'm retrofitting a 100 year old, balloon framed, two story farmhouse in Wisconsin (zone 6). All new windows, removing old siding to board sheathing. Will be blowing cellulose into wall cavities where possible (some have urea formeldahyde from a 1970's attempt). Planning to apply ARB over boards, then 2" polyiso, then vinyl siding. Window/door openings will be picture-framed with boards inset into the foam layer (3/4" board over 1 1/4" foam). Other penetrations will be treated like windows. I would like to use thicker foam but roof overhang is only 12" and adding 2" to 3" is about max.

In Green building techniques | Asked By Edward Odgers | Jan 20 16
5 Answers

Insulating and finishing partial basement with new attached crawlspace

I am in the process of partially finishing my basement in a split level home built in 1950s in N.W.suburb of Philadelphia, PA. (see attachment for layout of foundation of split level home and proposed construction of walls.)

In Interior design | Asked By Jeffrey | Jan 20 16
32 Answers

Curbless shower with a PVC liner -- how to terminate the liner at the floor?

I'm installing a curbless shower----Concrete slab-on-grade with a sump for shower.
Using traditional method for shower floor---PVC liner, with pre-slope and top slope mud beds.
2x2 tile on shower floor and 18x18 travertine on bathroom floor.

My question is how to handle the waterproofing interface between my sump and the bathroom floor level (like where the curb would have been).

In General questions | Asked By john walls | Oct 19 14
3 Answers

Basement insulation in Minnesota


In GBA Pro help | Asked By Jason | Jan 20 16
2 Answers

Insulation and air barrier

I'm starting a major remodel on a 1972 ranch home. SInce I am changing room locations and door and window locations most of the drywall on the exterior will be compromised. Using the DIRTFS (do it right the first time) theory I am just going to remove all of the drywall and replace the insulation with rock wool. I just finished reading about vapor barriers,and air barriers here and there is blood seeping from my ears.

In General questions | Asked By Dan Fedder | Jan 20 16
4 Answers

How to insulate a metal roof that does not have any roof decking?

We are building a red iron framed barn house. The house has all roof framing made out of red iron. A metal roof is being installed on the red iron frame work of the roof. The roof does not have any wood in it. All metal trusses. We are installing a metal standing seam roof on the roof and it will not have any roof decking. My question is: how to spray foam insulation on roof with out spraying directly to metal roof pannels? So when I have to remove the pannels in the future due to an unforseen reason I will not have to redo my insulation.

In GBA Pro help | Asked By Holley | Jan 19 16
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