Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

Advice can depend on climate -- Please specify in your question.

Please register for a free account or sign in to ask and answer green building questions.

The usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration:
Under the box labeled "More explanation," look for the words "File attachments."
Click that, and you should be able to attach a photo.

Thanks for joining the conversation!

Ask a Question >

9 Answers

20-foot vaulted ceiling & 1970s sagging insulation - need insulation retrofit advice

One of the additions to the house was a huge 20X24 living room with 20' vaulted ceiling. I guess they were all the rage in the 70s and so was insulation that is now sagging. I was looking with IR camera and I could just see these cold spot areas behind drywall where insulation has sagged. That room also drops 2 degrees for every hour, unlike the rest of the house where temps drop 1 degree per hour.

In Energy efficiency and durability | Asked By Apollo S | Jan 6 15

3 Answers

Low expansion foam or airtight tape for windows?

Hi all. One more air sealing question. Is there a preference here between using low expansion foam to seal the gap between a window frame and rough opening vs. tape? I've heard both methods referenced here. Should I consider doing both, or is foam alone sufficient?

In Green building techniques | Asked By Ryan Griffin | Jan 22 15

1 Answer

Persistant smell in house dense packed with cellulose

We insulated both attic and walls with cellulose. One bedroom that has the attic staircase in the closet develops an odor that the customer says "smells like the day you were installing it". When you open the closet there is no smell, so it is not coming down attic staircase. Customer has bought covers for air conditioning ducts that are in the ceiling. Room is heated by a boiler with recessed hydronic registers under windows. Pipes run through the exterior walls that are now dense packed. Shoe molding is missing from baseboard.

In General questions | Asked By Walter Gayeski | Jan 21 15

8 Answers

What are your thoughts here?

This does not really matter ultimately but its an interesting thought exercise.

In General questions | Asked By Alan B | Jan 19 15

3 Answers

Recommendations for concrete sealer?

Our contractor is recommending Clementone Clear Sealer for our new basement slab, which will be frequently used living space. The MSDS lists ethoxylated acetylenic diols, and the regulatory info says it contains substances listed under Title III of the Superfund Act and Prop 65. What less-toxic alternatives would be appropriate for this residential use? We will be moving in with a 1-year- but intend to add a large dog. The uses include mud room and playroom as well as laundry and guest quarters. The concrete has a black tint but otherwise as yet unsealed.

In Green products and materials | Asked By elizabeth skewgar | Jan 21 15

22 Answers

Best HVAC for a 1,100 sq. ft. passive solar house at 46 N latitude?

We are building high-performance, all electric, 1,100 sq foot passive solar home in cold weather winter climate with hot, humid summers. Slab on grade. Exposed concrete floor as thermal mass. Natural gas is not available. Winter temps infrequently reach -20 to -30 degrees range in December and January. We will use modeling to size heating and cooling system. We will have two bedrooms, open living, dining, and kitchen (primary solar gain area). In addition, there will be a full bath, 1/2 bath, mudroom, and mechanical room. Heating days the last 3 years: 7,065; 8,980; 9,799.

In Mechanicals | Asked By Randy Bunney | Dec 26 14

15 Answers

New study on heat pump water heaters' reliance on the home's heating system and viability of ducting the HPWH

https://www.aceee.org/files/proceedings/2014/data/papers/1-1203.pdf

This came out sometime in 2014 and I haven't seen anything about it before.

The points that I took from it are:

The heat "stolen" by the HPWH is less than expected, at least when located in a room that is partially on the exterior surface of the home.
Exhausting the HPWH to the outside without also ducting its intake can have a harmful effect on the home's heating energy use, since it needs makeup air, which comes from outside and can be even colder than the output air of the HPWH.

In Mechanicals | Asked By Nick Welch | Jan 9 15

1 Answer

Guest Bloggers

Well hi there,

I was wondering to whom I should be in touch with to discuss guest blog opportunities. Please let me know!

Best,

Jessie

In General questions | Asked By Jessie Strauch | Jan 21 15

6 Answers

Taping seams of tongue and groove sheathing

Hello, I am remodeling a powder room in a 1928 brick colonial.

While the wall is open I would like to air seal and insulate the cavities from inside the house.

To the best of my knowledge, the sheathing appears to be 3/4" Tongue and groove. I would like to tape the joints and the areas along the studs with 3M All Weather Flashing Tape. What is the recommended overlap of the tape ? It comes in a 4" width, will 2 inches be adequate ?

In Green building techniques | Asked By Kurt Kiley | Jan 20 15

6 Answers

Renovating an older home

We are renovating our house in North Vancouver, BC.
This area gets about 2500 mm of rain per year.
All the siding is removed and underneath, are 1x8 ship lap boards over 2x4 framing.
I removed the old building paper and covered with Typar for the winter.

I was thinking of installing inch and a half Roxul Comfortboard over top the Typar and under the rain screen but I understand that the bottom edge of the air barrier should not be sealed so that any water that gets behind it, can drain.

However, with the board sheathing, I don't get much in the way of air sealing.
Should I remove the

In Green building techniques | Asked By Aaron Gatzke | Jan 17 15

Register for a free account and join the conversation