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

[Click map to enlarge]

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!

1 Answer

Chimney and ceiling insulation

I've been struggling with how to "legally" and safely get a class a chimney through r80 insulation in a ceiling The listed hardware only accommodates 10" of insulation above framing. Is the only alternative build a plywood box (chase) that provides 2" clearance around the chimney from ceiling to roof? Would an 8 sided duct made of duct board be a safe and legal "chase"? Can the "chase" end short of the roof?

In General questions | Asked By Jerry Liebler | Sep 8 12
2 Answers

How do I insulate a room with a concrete floor and concrete roof?

This room is used year round. The room has a garage underneath the floor. The ceiling is also the roof which only has a rubber sheeted on the outside. We live in Pittsburgh which is very cold for a good 4-6 months of the year with snow, and reasonable amount of rain in the season.

The height of the room is only 7.5 ft. So interior clearance for insulation is at a premium. Can we insulate from the outside on the roof and subfloor?

The walls are made of concrete block with firring strip, rigid foam, and drywall. I suspect it was a garage once.

Thanks for your help.

In Energy efficiency and durability | Asked By Matthai Markose | Sep 5 12
4 Answers

Framing splayed window openings with double frame walls

I'm building a double frame house with 2x4 ext, 2x3 int offset. I know that usually people line up the interior and exterior framing at doors and windows to make the boxes. Are there any words of wisdom or ideas about details for building boxes for "outie-style" windows with sides that are splayed out at 45 degrees?


In Green building techniques | Asked By tim desmond | Sep 5 12
3 Answers

Problems with mini-splits?

I'm looking into mini-splits for my new house (2700 sqft SIP construction zone 3) but my HVAC contractor mentioned that they have had a terrible time with sensors failing on both the indoor and outdoor units. His feeling is that their complexity and maintenance costs outweigh any efficiencies. Does anyone have any experience with mini-split maintenance?

In Mechanicals | Asked By Chris Baddorf | Sep 7 12
3 Answers

In western NC I am considering using 7" of closed cell foam in a retrofit project and wonder what costs are/ sq. ft.?

in a retrofit cathedral ceiling. Any idea of cost per sq.ft.?

In Green products and materials | Asked By John Duncan | Sep 6 12
2 Answers

Is painting brick fascia good, bad?

My wife wants me to paint the brick fascia on our circa 1965 house located near Baltimore, Maryland, zone 4A. What are the pros and cons of doing this with respect to reservoir effects. If it is ok is any special prep work required and what kind of paint should I use? Also, I notice there are no weep holes; was this common in the mid 1960s; is it something I should do something about? Thanks for any help.

In General questions | Asked By Windsor Furr | Sep 6 12
3 Answers

I have few questions I need answered that deal with rigid foam

1. I thought Green Building Advisor had more information about fasteners for rigid foam? I've done a search and all I've come up with is one product is there a link that I'm missing?

2. I'm going to put foil on the outside of my foam for a radiant heat barrier but I would like to know it there's a spray adhesive I can put on the foam then stick the foil to? I'm putting a stone exterior over the foam and I need the foil fixed to mark out lines for my studs? The foam I'm using is Foamular 250.

In Green products and materials | Asked By michael kasales | Sep 6 12
1 Answer

Is the site down? Not seeing any of the usual stuff, just one big ad.

See for yourself

In GBA Pro help | Asked By matt berges | Sep 6 12
6 Answers

Low E House wrap

Has anyone had any experience with Low E House wrap. Due to the existing design of this new home I am looking for the least expensive way to minimize thermal bridging. I am building with ICF foundation, 2x6 exterior studs, spray foam insulation, 1/2 plywood sheathing, cement board siding. At this stage of the game I can not afford to have this home re engineered. Looking for as efficient as I can get.

In Energy efficiency and durability | Asked By Dana St.Ours | Mar 26 12
1 Answer

Polyethylene sheeting alternatives

Our project hoped to omit a poly air/vapour detail by opting for air-tight sheathing (with larsen truss over top)and a vapour barrier paint (vbp). unfortunately, the building inspector is not only not buying what i'm selling, he is clearly not impressed. so, i am commited to our air-tight sheathing approach: will it be unhealthy for the wall system to then use a conventional poly vapour barrier detail? the british columbia building code (bcbc) allows for a "wall coating" alternative to poly; does anyone know of a specific product that meets these specs?

In General questions | Asked By erik olofsson | Sep 6 12
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!