Community: GBA Pro help

Q & A Instructions

[Click map to enlarge]

The web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

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

If you want to post a question, 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!

7 Answers

What direction should I go with my new/used home?

I purchased a 23 year old home to accommodate my growing family. It was constructed with double wall construction, wood foundation, Envirovent system etc. We live on Nantucket Island.
I am planning to install a mini split system and have questions on further improvements, possibly solar, that are upcoming.
My first inclination was to update systems based on the recommendations of local hvac contractors until I realized that my new home is unique and that I might need specialized consultation from someone more familiar with this "type" of home.
Any advice or suggestions are welcomed.

Asked By todd stout | Nov 29 16
10 Answers

Polyiso foamboard (foil-faced on both sides) used in unconditioned space

Hello All,

I live in Portland,OR climate zone 4 & 5 marine.
I consider it mainly a heating climate and lots of rain.

I have a cape cod style house with 13/12 pitch roof on the main roof.
I have three gable dormers on the front, two new ones and one existing all with 20/12 roof pitch.
I just had ridge vents installed on the main roof and all three gable dormers.

I have managed to keep my new HVAC ducts in the floor joists and the are only exposed in the knee wall area before to going down into the (conditioned) floor/ceiling joists on the way to each room.

Asked By Chalin Hutasangkas | Nov 13 16
4 Answers

Insulation for vaulted ceiling

We re-roofed our house this summer and found a lot of damage over our family room with a vaulted ceiling. We replaced the plywood and are now redoing the underside. The roof has a roof ridge vent and ventilation holes in the soffits. We are creating on-site baffles with 1" rigid foam boards. We are planning to use R30C insulation which is denser for cathedral ceilings. The question is do we use faced or unfaced, and do we need to use plastic sheeting as a vapor barrier? We want to get it right this time!

Asked By Kim Howard | Nov 22 16
8 Answers

Which foam system to use in air-sealing the attic in an older home before adding cellulose?

I am getting two different recommendations from contractors and could use some guidance. We live in Portland, OR in a 1951 ranch-style house that was extensively remodeled in 2005. We started to significantly upgrade our attic insulation & air-seal and discovered that we have a vermiculite/asbestos remediation problem to solve first. Some of the abatement cost is covered by the ZAI Trust fund.
Result- all the existing insulation (vermiculite, old cellulose, blown-in fiberglass) is being removed first. Then, air seal and blow-in cellulose to R49.

Asked By Kent Snyder | Nov 16 16
5 Answers

Is closed cell spray foam between rafters in an old house a good idea?

To all, but especially to Dana Dorsett and Martin Holladay,

Asked By Rebekah Haworth | Nov 15 16
5 Answers

I need help insulating my unvented cathedral ceiling

Here's what I have: I am building a house in my existing pole barn. When I built it, I put my roof nailers on 2' center, then put down fan-fold insulation, then placed my metal roof. I am going to leave my trusses exposed on the inside for a cathedral ceiling, and was wanting to put metal up for my ceiling between the trusses.

I am trying to figure out how I can insulate this. Can I use rigid foam board and put it all the way against the fan-fold and make it airtight, then put up my interior metal?

All the help on this would be much appreciated. I am stumped. Thank you.

Asked By Thomas Duncan | Nov 11 16
5 Answers

OK to put rigid foam between rafters to convert a vented attic to unvented, for storage?

To all,

We live near Chicago and have a split level house built in 1959. I would like to use rigid foam to convert our two vented attics to unvented so that we can use them for storage. The rafters are 2x6, so there is 5.5" of depth under the roof deck to put layers of rigid foam into as a "stack of pancakes" between the rafters. I would also like to attach 4'x8' sheets of rigid foam (at least 1/2 inch thick) to the lower edge of the rafters to prevent thermal bridging.

Asked By Rebekah Haworth | Nov 9 16
11 Answers

I have an A-frame roof (scissor truss)

I am using 2" EPS as a baffle with 2" of vent space (I am using 2"x2" sticks of EPS glued to the underside of the roof deck for spacers). I am using "Great Stuff" to seal all the joints (where the baffle contacts the...)

I read somewhere to only put the "spacers" in the corners of the rafter space. I started this project before I read that, and I have some of the spacers more or less in the middle of the rafter space (not to one side or the other).

Any suggestions or concerns?

Please educate me.

Thank you

Asked By Jason Fuhrman | Nov 1 16
2 Answers

How do I ventilate a basement?

I live in a 1967 house in zone 6. I need suggestions on how to best ventilate our basement as we're finishing it. We want to ensure there's good air quality year round. We have central air and baseboard heat throughout the house, except the basement. The temperature is generally comfortable down there w/o AC or heat.

We've had a musty smell down there despite having no water issues, french drains, sump pump, downspouts extended from house and a 70-pint Frigidaire dehumidifier.

Asked By Masb Hroncich | Nov 3 16
Register for a free account and join the conversation

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