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

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com 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!

9 Answers

Combustion air and/or exhaust air makeup

I have a home that was built this year - mostly just code standard for air tightness and insulation in Minnesota.

The question i have is that we have a fresh air inlet duct (~5") that drops into our basement - seems unneeded with our appliances and windows/tightness.

Have a high eff furnace with piped combustion air, gas power vented water heater, no kitchen hood exh, gas drier and 3 small exhaust fans.

I can turn on all my fans and i notice no change in the amount of air coming from duct. Plus i read things like

In Building Code Questions | Asked By Nick T | Nov 13 13
1 Answer

Creating a wood stove draft in an airtight home

Hi. I am in the process of deciding what type of wood stove I should consider for a new construction of an airtight home.

I am sold on the Jotel F 602 for size, BTU output, price, reputation, etc. Do I need a fresh air kit in order to create a good wood burning fire in a home the I presume will be very airtight? Are there other "tricks" that would work just as well and not create another penetration in an exterior wall? There is not much literature out there pertaining to Jotel's fresh air kits, but I know they make them for this stove.

Thanks in advance.


In General questions | Asked By Matthew Michaud | Nov 14 13
2 Answers

ERV distance from stove

How many horizontal feet/meters from a stove do you think ceiling register ERV returns should be kept?
Does anyone know of any actual tests that produce data useful for suggesting a minimum distance for this?

In General questions | Asked By Bill L | Nov 13 13
3 Answers

Gable and ridge vents literature


Should I install a ridge vent with gable vents and without any soffit or other eave venting? The attic space is currently vented with a gable vent on each end (no fans or other active). The house is a gambrel-style / barn-style / dutch colonial so there is also unvented roofing shingles around the 2nd floor. The two areas (steep shingles around 2nd floor and gradual above attic) are not connected, save any framing gaps between the two.

In General questions | Asked By John Helder | Nov 12 13
1 Answer

Two ductless minisplit heat pumps for climate zone 6A

I'm trying to decide if I can utilize ductless mini split heat pumps as our primary source of heating. We will have a fireplace, but I can't depend on this to supplement the required heat for various reasons. Budget is a factor, and what we are trying to achieve is something along the lines of the "pretty good house" idea. Not by any means a Passivhaus, but a stepping stone.

In Energy efficiency and durability | Asked By Kyle Newman | Nov 13 13
1 Answer

Air barrier in stairwell between 2nd and 3rd floors and their HVAC zones?

Is there a product that can be placed at the top of an open stairwell between home floors that will keep the HVAC zones on each floor separate. Last winter I used a cut-to-fit piece of rigid foam board. Is there something more professional.?

In Energy efficiency and durability | Asked By John Snoddy | Nov 13 13
2 Answers

What insulation can I add to my attic?

I currently have blown-in loose-fill fiberglass in my attic. Do I have to add the same product, or can I use cellulose?

In Energy efficiency and durability | Asked By Greg Tritley | Nov 13 13
8 Answers

Polyethylene as an air barrier in very cold wall assembly

My question pertains to the use of a polyethylene air barrier (6 mil) within a double wall assembly (and ceiling) in a very cold climate. My concerns when we came up with this wall were obviously wall performance, related to moisture buildup and drying, as well as keeping the build relatively inexpensive both in materials/labor while at the same time providing me with a system provides high R-value while decreasing air leakage.

In GBA Pro help | Asked By Matthew Michaud | Nov 13 13
3 Answers

Extremely humid interior atmosphere

We are currently working on a project in the Chicagoland area at a water reclamation district. We are re-roofing a building that enclosed the water filtration pools with extremely high levels of humidity.

We are installing a new roof membrane over the concrete topping slab on the roof and running vertical on the multi-wythe brick walls that serve as both parapets as well as extend up to a higher level than the adjacent roof. The roof membrane will be attached to an exterior grade plywood that is attached to the brick.

In General questions | Asked By Nathan Kipnis | Nov 12 13
4 Answers

Interior walls using rough cut lumber and insulation?

We are using a restored barn frame to build a home. Our thought was erect frame, then wrapping the frame with painted rough cut, then applying 15lb felt paper, then framing w/ 2x4 or 2x6. We would then insulate w/ fiberglass, apply OSB sheathing, house wrap and then the necessary R value of foil faced poly iso to conform w/ code, being careful to seal all joints. Is this a proper wall build up or is there a better way to do this?

Thank you for your time GBA pros have been very knowledgeable.


In GBA Pro help | Asked By matt bowman | Nov 12 13
Register for a free account and join the conversation

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