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2 Answers

Heat loss from floor drains to daylight

We are in Minnesota (Zone 6a). 2200 sq/ft single level, slab on grade.

This question has been in the back of my mind for quite some time and I can't find an explaination about heat loss from floor drains to daylight. I will heat our garage to about 45 degrees F, and have 2 floor drains that run to daylight. Seems to me that this will be not only a drain for water, but a drain for heat as well. Are there any stratagies for minimizing heat loss through the drain? We are not allowed by code to connect this to our septic system.

Asked By Scott K | Oct 21 17
4 Answers

Attic insulation: Mineral wool batts or blown-in cellulose?

I'm in NJ, right on the border of Climate Zone 4 and 5. 1600 sq ft attic currently R-13 batts with lots of voids. I'm planning to airseal and reinsulate over the next month or two and need some help deciding between mineral wool or cellulose. In an ideal world, I'd take out all the existing insulation, clean up, install baffles, air seal, and then blow in insulation.

Asked By Jay | Oct 20 17
2 Answers

Closed cell spray foam/cellulose combination

To all,

Background: 1500 Sq Ft. single level home, Northern Minnesota Zone 7, almost 10,000 HDD.

I am getting ready to insulate my double studded walls. The wall cavity including 2 2x4 24"OC studs separated by a 1" gap for a total cavity of 8". The ceiling has 2' energy heel trusses with 24+" of blown in cellulose

The original plan was to insulate the whole wall in cellulose, and at R3.9/inch the goal was 31 with no thermal bridging. Inside the cavity there was going to be a smart membrane (Intello Plus)

Asked By Steve Lenertz | Oct 21 17
21 Answers

Automatic control for passive solar overheating in winter?

Hi, I’m designing a passive solar house and attempting to gaining the most energy from the sun, but the more energy you try capture, the more likely overheating becomes a risk on those warmer, sunnier winter days. I was thinking it would be simple enough to have an ERV with a bypass that can exchange overheated indoor air (say 80°F) with the cooler outdoor winter air (say it’s 60°F) when the indoor temperature hits a upper limit setpoint (say 75°F) and the outdoor temperature is cooler.

Asked By Mike AbiEzzi | Oct 20 17
2 Answers

Should I vent an unconditioned roof?

Home Built: 1915
Climate Zone: Marine 4 (Seattle)
Unconditioned Attic, no ductwork

Roof Joists: 2x4
Sheathing: OSB
Pitch: 9/12
Reroofed: Not sure, maybe 20 years ago, asphalt shingles

Ceiling Joists: 2x4
Ceiling Type: Flat, no vaults.
Square Feet: 900
Existing Insulation: Cedar roof shingles thrown on top of fiberglass bat.

Venting at Eaves: None. Zero. Zip.
Venting on Roof: 4 black roof vents (galvanized steel?)

Future Insulation: R-49 or R-60 blown (cellulose or fiberglass)
Future Modification: Whole house fan. (Maybe?)

Asked By Brad Steeg | Oct 21 17
1 Answer

Vaulted ceiling, open attic

I have two vaulted ceilings that I am trying to work out how to insulate. I have read all the material here on insulating cathedrals. However these are essentially a variant on an unconditioned, vented flat attic. If the roof is 6/12, the ceiling is 3/12. Unfortunately while they are not a classic cathedral with only a stud's depth, they still have very little space between the ceiling joist and rafter, ruling out fluffy insulation. (The R-38 batts already brush the roof sheathing halfway down the slope) Dense pack, of course, I hear is a very bad idea due to moisture.

Asked By pshyvers | Oct 21 17
2 Answers

Installing a one piece shower


My cousin and I are installing a one piece shower this weekend, in his guest house he is building on his property. Property is located in zone 3.

I told him I would do a little bit of research beforehand.

He is using an interior vapor retarder called intello plus. I am wondering if it is ok to install the shower directly over this or if there is any reason drywall should go up first?

Also, the manufacturer requires no cements bed under the shower. Would it be wise to lay a vapor barrier cutout underneath the shower or can we just install directly over the plywood subfloor?

Asked By MichaelBa | Oct 21 17
0 Answers

How to get Passive House educated?

Hi everyone,

Asked By DHTaylor | Oct 21 17
8 Answers

Foam first or last in cold enclosed porch floor?


I have seen this question answered many ways while searching online, so I thought I would pose it here. I know there is another thread on this topic, but it seemed worth posting again.

When insulating an enclosed porch that is not climate controlled, should the layering be: pink foam board affixed to the floor underside, fiberglass batts, plywood for vermin control?

Here's the application:

Asked By JonesyHome | Oct 12 17
1 Answer

Rigid insulation above the roof deck

I'm considering a roof design that would place all the insulation above the roof deck with no insulation below. I would use polyiso with a top layer of EPS as recommended in your blog post on the topic. The project is in Climate Zone 4 (Seattle area) and I want to have an open beam look in the ceiling. Placing a layer of fluffy insulation below the roof deck would needlessly complicate the roof assembly. What are the potential problems I could have if I installed all the insulation above the roof sheathing, which will actually be the finished ceiling?

Asked By Stewart Breslin | Oct 20 17
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