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!

5 Answers

Should we insulate the attic floor or roof where attic contains AC system only?

We have an uninhabited attic space (roof slope too low) that has a high velocity AC system air handler and distribution in attic space with blown in insulation between attic floor joists. Heating is a conventional hot water system with boiler in the basement. The attic is vented with both soffit and ridge vents; attic temperatures currently max out around 125 degrees where we live in southeast Michigan.

In Energy efficiency and durability | Asked By Douglas Forman | May 29 12
3 Answers

How do I rough-in a ceiling service cavity before inspection and insulation?

My addition that I am building has 9 foot ceilings, but I want 8 foot ceilings in the bathroom and I want to keep the two bath ventilation fans and the can lights inside the building envelope. So, I decided to create a soffit that essentially covers the entire ceiling (or a service cavity, I'm not sure what it would be called). The OSB attached to the bottom of the ceiling joists and around the top of the walls will be caulked and taped to create an air tight seal.

In Plans Review | Asked By Robert Sanders Jr | Jul 1 12
0 Answers

I am addind an addition to my home with 42" deep foundation that is tieing in to an existing 72" foundation.

What do I need to concider in regaurds to Concrete and Drainage tie-ins.

In General questions | Asked By Tom Ader | Jul 1 12
3 Answers


If I want to install a wood stove through the wall or the roof and both have 6" of foam board on the exterior, are there additional precautions to prevent exhaust heat duct from melting or causing a fire around the insulation? For example, install one or more layers of cement board over the 6" of foam. Then install through the wall or roof duct work.

In Energy efficiency and durability | Asked By HORST SCHMIDT | Jun 30 12
10 Answers

Help for new Broan Smartsense fans as alternative to HRV

I have seen articles here talking about the new Broan Smartsense ventilation fan system and had a few questions about using it as an alternative to an HRV...

I am curious if anyone has used them, or designed a house for them - we are in our final design phase and our plan checking company requires make up air calculations.

2800 sq/ft 2 story house - stick built - California climate zone 3

The idea is to put in 5 Broan fans - then have the makeup air dampers attached to them.

My question is where do the intakes go? To the bedrooms (3), the upstairs (1), laundry (1)

In Mechanicals | Asked By Monty Worthington | Feb 1 11
0 Answers

Lstiburek Videos

I have started organizing some of the links I have collected on Pinterest Boards
This board is for Joe Lstiburek Videos
If you have links to other Videos
please post here and I will add them to my board(s)


In General questions | Asked By John Brooks | Jun 30 12
1 Answer

I have a new window with only a 10 in opening - Looking for a window air conditioner which will fit

Can you help me?

In General questions | Asked By melody bohr | Jun 30 12
5 Answers

HRV for a 3000 SF All Brick Multi Wythe home in MN?

We have an almost 300 sf Brick load bearing wall home in MN. There will be no insulation in the home but in the attic (We won our case with the city because of the risk on insulating the walls). There will be drywall installed on the furring strips on the walls. We are installing a kitchen hood that is a 600cfm. Wondering what size HRV is required, and what rooms are recommended to have the vents in.

In Mechanicals | Asked By Kristina Beedle | Jun 29 12
4 Answers

Using Fluid Applied Tyvek as an air barrier inside the home

I have been doing a lot of research lately on air barriers and have read up a lot on EcoSeal and EnergyComplete. Both products seem superior to simply applying caulking to joints and cracks. My question is since both Ecoseal and Fluid Applied Tyvek are vapor permeable and air barriers, what would the downside be in applying the Tyvek on the interior of the house where you would normally apply EcoSeal or EnergyComplete?

In Green products and materials | Asked By Joe LaFreniere | Jun 28 12
1 Answer

m2·°C/W per inch versus R-value or RSI values?

It appears that the latest insulation performance values are being related in (area) x (temperature) divided by watts (energy/time). In the recent article "Understanding Energy Units" you clarified and defined types of energy units, including watts. I read it in hopes of understanding what m2·°C/W ultimately means when selecting or comparing different insulation materials but after reading it I am still left in the dark.

In Energy efficiency and durability | Asked By David Stewart | Jun 29 12
Register for a free account and join the conversation

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