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26 Answers

Using polyisocyanurate insulation on the exterior of a home

I just read one of the discussions’ on the use of polyisocyanurate insulation on the exterior of a home and how it acts as a vapor barrier and not to use it because it doesn't breath, thus resulting in potential condensation and mold problems within the walls. My concern is that I am currently getting ready to reside my house and I have already installed this on 50% of my home. I wanted to only add 1.5" thick foam to work with my 8" windows jams that I have upgraded to So I wanted the most R value possible from a foam. And polyiso gave this and It was also cheaper then the 2" XPS.

In General questions | Asked By Shane Kingston | Jul 3 11
24 Answers

Is a thin layer of rigid foam better or worse than nothing?

Hi,
I am building near Madison, WI. Our house plan has walls that consist of (outside-in): Cedar or Hardieplank, tyvek, 7/16 OSB, 16" on center-studs, R23 bib insulation, 6 mil vapor barrier, drywall. My question is whether 0.5" of rigid foam insulation added to the exterior, inside the Tyvek will do more harm than good. I gather it will reduce thermal bridging, but it is too thin and may lead to moisture problems. I know 1.5 to 2" of rigid foam is the correct thickness. So the question is, should I just ditch the foam?

Thanks in advance.
Adam

In Energy efficiency and durability | Asked By Adam Bayliss | May 6 12
5 Answers

Heat loss and condensation through mechanical penetrations in the building envelope

A great deal of space here is dedicated to building air tight well insulated homes. This of course is good but what products can minimize the heat loss and vapor problems that arise from the penetrations in the building envelope by mechanicals? For instance how can a dryer vent be gasketed to an R of more than 1. Likewise how are the bathroom and kitchen vents handled to improve efficiency? Also concerning the dryer vent what is done with the moisture that can form when the moist warm exhausted air hits the cool outside air?

In Mechanicals | Asked By tom ruben | May 10 12
3 Answers

Indoor air quality

Hello GBA!

We are looking for solutions to help with the indoor air quality of our home. We live in the Minneapolis, MN area and have switched our home from forced air to a hydronic system. This was done to enable us to remodel our home to better suit our needs. Due to this change and the tighter envelope of our house, we are experiencing the typical condensation on our windows during the winter. Are there any ideas out there that may help us control the air quality inside our home?

Thanks for the help!

Mark and Melani

In GBA Pro help | Asked By Mark Bowser | May 12 12
27 Answers

Did an add-a-level, insulation options are of concern with solar panels

I have just completed an add-a-level on a New Jersey cape cod home and am at the point where I need to decide how to treat the insulation issue up there. I might add that there is a furnace up there in the attic with lots of ductwork which the installer wrapped. The south facing roof will be completely covered with solar panels. The existing insulation on the first floor is admittedly not the best, but short of ripping out all the walls there wasn't much I could do that I was aware of.

In Energy efficiency and durability | Asked By Monica | Feb 6 10
8 Answers

Mini-split, air circulation and noise transmission

We are considering using a mini-split system on our new tight home (double wall cellulose on a insulated slab) in Upstate NY (Zone 5a). We are both consultants with full time home offices.

One option is a hidden short ducted system on the first floor (1,500 sf) to duct air to the main living area and the master bedroom area and a regular mini-split unit for the upstairs (800 sf) where we will have our two offices, a bath, storage and a guest room. Our mechanical room is on the second floor. I don't want a visible unit on the first floor.

In Mechanicals | Asked By Elizabeth Kormos | May 10 12
8 Answers

Where is the water coming from?

I am working on a house about 30 miles north of NYC. It has had a paint peeling problem for 15-20 years, ever since the house was renovated. It has many large thermopane windows, all with copper pans below. It has a narrow continuios vent at the fascia, no soffit, and a 41/2" pitched roof over the windows that extends to the ridge. the rest of the roof is a 6 1/2" pitch with the same venting detail. there is a continuios ridge vent. It is sided with 3/4" x 10" redwood clapboard siding that was back primed with a 2 1/2" overlap over Tyvek and Barricade wrap around window openings .

In General questions | Asked By James DeSalvo | May 9 12
1 Answer

Polyiso designed for roofing OK in crawlspace?

I want to seal and insulate my crawlspace walls and rim joist area in an affordable manner, which for me is about as close to zero as possible. So I found a guy who has a bunch of used 4'x8'x1.5", with black paper facing on both sides, for $5 per sheet. In looks like its pretty good shape from the photos I've seen and the price seems like 1/5 the retail price.

My question is: what is the purpose of the black paper facing and is it OK to use in spaces other than roof applications?

In Green products and materials | Asked By David Martin | May 10 12
4 Answers

Lighting strategies

i could not find this on any other forum and hopefully my post is relevant

Is there a way to get natural sunlight into a dark room? I have a 1st floor living room in an attached house (attached from both sides) and this room runs north south and has some windows on the south-facing side. Could I use some technique to light up the whole room using these windows? I see a technique listed here but it needs direct access to the roof
http://www.yougen.co.uk/blog-entry/1760/How+to+bring+sunlight+into+a+dar...

Thanks

In Green building techniques | Asked By sam dhak | May 9 12
6 Answers

What is the the thermal mass heat storage capacity of 1/2 inch of sheet rock?

I understand that the BTUs per degree of F per square foot of 4" thick brick pavers is 9, of builder's brick is 6.5 and of hard wood is 1.7 per (Johnston and Gibson, Towards a Zero Energy Home). What are the BTUs per degree of F per square foot of 4" thick sheet rock?
I am building a 1550 sf one-story zero energy home in Bend Oregon. It will have .6 ACH@50p and will have 50 R walls and floor and 60R ceiling. The windows will have a .2 u-value and a SHGC of .6. The south facing living area is approximately 600 sf.

In PassivHaus | Asked By Joseph Emerson | May 9 12
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