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2 Answers

Cold climate building envelope question - Adding styrofoam to the outside of the wall

- possible condensation issues, i.e. a second vapour barrier created in the wall cavity. Assuming the typical situation where a poly vapour barrier is installed behind the drywall and fg insulation in the stud cavities.

Asked By Wm Smith | Apr 20 09
5 Answers

Energy Efficieny upgrades for historic buildings

I have a project that entails the rehabbing of over fifty small historic buildings for energy efficiency and comfort upgrades. Because these buildings are part of a National Historic Landmark, we are very limited to how we effect the exterior of the structure including window changes. My plan is to start with insulation upgrades to the attics and crawl spaces. Funds are limited as this is part of a non-profit organization so I want to be sure to spend the money wisely.

Asked By Jeff Medanich | Mar 11 09
1 Answer

Fiberglass over a slab

We are bumping out the garage and turning the exiting garage in to a family room. In the process we are framing on the slab to meet up with the floor in the house. We have put down a vapor barrier (6 mil plastic). The plans call for R19 Fiberglass in the cavities. My concern is condensation within the system (tile will be the finished floor.) also should this space be vented in some manner as well? This project is in Wisconsin so there is a great deal of temperature change. I feel that we should be putting down minimum 1” foam and air sealing all joints.

Asked By Richard Monserud | Apr 20 09
10 Answers

Flashing details

I understand the advantages of using "outsulation" (rigid insulation on the outside)
I am still having trouble finding satisfactory details.
Especially concerning Window head details used with siding.
I went for the pro account here at GBA and started looking at the details.
I still wonder if anyone has actually constructed these details to see what they will look like and how they fit together.
It looks to me like the head details show the water draining behind the window trim(casing) and somehow magically weeping out between the bottom of the casing and the flashing.

Asked By John Brooks | Mar 17 09
3 Answers

Should I convert my boiler from gas to electric?

My house's heating system is gas-fired hot water. It's a fairly efficient system, but I've been thinking of swapping the boiler out and installing an electric boiler.

Here's my thinking, Electric boilers are more efficient, of course. But they give me more flexibility in the actual "power source." With natural gas, the prices fluctuate during oil crises, and there's only one source for gas in my city.

Asked By Brian Siano | Mar 25 09
6 Answers

What kind of exterior rigid insulation should I use?

I am working on a series of small 1950 vintage homes. I am planning on filling the walls with cellulose blown from the outside, adding exterior rigid insulation, and re-siding. The exterior finish is not yet known, but I would like to offer the Architect something that works regardless what is chosen (within reason).

I had been thinking about some kind of un-faced extruded foam (so that I do not add any vapor barriers to the system) but people keep giving me funny looks when I say this.

Any suggestions?

- Ron

Asked By Ron Flax | Mar 23 09
5 Answers

Using 1" XPS as the vent baffle

I am thinking of using 1" XPS as a vent baffle in a cathedral ceiling, similar to what is shown here:

I wouldn't actual use that product, but the same idea. I am thinking of spacing the xps 1.5" off of the underside of the roof sheathing, and sealing any gaps with a combination of sprayfoam and tape. The roof would have soffit and ridge vents. The rest of the bay (approx 7") would be insulated with fiberglass bats. I am building in a cold climate, and the space is a conditioned room over an unconditioned garage. The roof is 2x10 stick framed.

Asked By Tobias Richon | Feb 27 09
2 Answers

Does it make sense to use ICFs for a frost protected shallow foundation?

I will be building a house near Amherst Ma. in an area with a high water table. FPSF seems like the way to go. ICFs are quick and easy. Is there any reason not to use them for this? Any opinions on insulation - xps or eps? Any recommendations on waterproof material under the slab? I have heard polyethylene gets brittle and breaks down over time.

Asked By Ralph Hill | Mar 11 09
3 Answers

Good assembly for cathedral ceiling with blown-in insulation?

This is a hypothetical question but it's something I want to consider for my next house.

I like the natural aspects of cellulose insulation, and I like cathedral ceilings -- what are good ways of making the twain meet? There are advantages to rigid foam, e.g. eliminating thermal bridging (and I noticed that all or almost all of the cathedral details provided on the site use rigid foam), but can cellulose be used and obtain similar performance? How should it be framed?

Thanks in advance,


Asked By Tristan Roberts | Jan 22 09
2 Answers

Basement Window Wells and Exterior Rigid Insulation

I'm working with a builder who is having difficulty detailing a window well with exterior rigid insulation. All the great details on this website and on swear by exterior rigid insulation for basement foundation walls, etc. But for the life of me, I can't find any details on how to deal with a window well space. The foam is exposed to the outside, so what's the best way to protect it and cover it for appearance? How do you trim this out around the window? Does anyone have a link to good details for this?

Asked By Adam Stenftenagel | Feb 21 09
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