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!

6 Answers

Rainscreen at bottom of sliding door details

Hi guys,

I am currently residing my house. I have 1.5" eps foam, then Tyvek WRB on top. Then on top of the tyvek I have a rain screen (3/4 plywood strips) and will be using vinyl siding on top of that.

Attached are pictures of my sliding door. I was wondering if there were any details on how to flash the bottom of the door. As you can see in the picture I also have my outside trim in 3/4 plywood as well. I will be wrapping up the trim in aluminum trim.

In General questions | Asked By Dan Nospa | Apr 25 16
2 Answers

Does a 6-12 roofline mate up well with 12-12 roofline?

I've got a 2 story 26' by 32' cottage with 12-12 pitch.

I would like to add a 12' by 16' screened in three season to the gable side on the North side.

The Contractor recommends matching the cottage roof pitch (12-12)...

In General questions | Asked By Mark Conroy | Apr 25 16
34 Answers

Condensation on windows with steel SIP home

We built a steel SIP house this summer near Hannibal, MO. We've been very happy with the results with one exception. The builders used steel L-angle to wrap the windows on the outside in order to better square the openings before installing the windows. They also installed the windows. This steel angle is not thermally broken at all. One part of the angle lays against the steel panel skin on the outside, and the other angle extends past the window into the living area about 2".
We do not have siding on the home. We have left the exterior steel exposed.

In Green products and materials | Asked By Jeff Carroll | Dec 13 15
2 Answers

1:300 net free vent area ratio vs. continuous soffit vent

In the GBA article Lstiburek’s Rules for Venting Roofs (07-24-2011), he notes the importance of having continuous soffit vent so the entire under side of the roof gets air flow. Although he does not mention the 1:300 rule (in that particular article) he does talk about splitting venting 60% to soffit and 40% to ridge so the space stays at a higher pressure than the inside of the house.
I assume that we are suppose to still follow the 1:300 guidance for determining NFVA. BUT, what if running a continuous soffit vent means the ratio is going to be more like 1:150?

In Energy efficiency and durability | Asked By Jack Randall | Apr 24 16
9 Answers

Advice needed: Recycled XPS rigid foam

I've located 4x8 sheets of 3" recycled foam board. This is DOW blue board, claiming to be 3" thick.

Should I nab this up for exterior insulation around the foundation? The price seems right and I love to recycle.


In Green products and materials | Asked By Drew Baden | Apr 19 16
10 Answers

Straight line for laying blocks when it's too windy for string?

I'm about to start laying four courses of CMUs for the stem wall of a simple rectangular house's foundation.. It's been very windy here and will continue to be for another few weeks. On the one calm day we had, I projected the string lines for the outer edges of the house downward, drawing lines on the surface of the footing itself so that I would have a straight, accurate line when it's windy, but as I plop mortar down to lay each block in the the first course, those lines will get covered.

In General questions | Asked By Jeff Cooper | Apr 23 16
0 Answers

Please help by answering this survey!

Hi everyone! I'm a high school student that is doing a study on the household efficiency of Solar Panels. If you live in Southern California and have solar panels, please help me by answering this survey! It's fairly quick and you'll be helping a great deal!


Thank you!

In Energy efficiency and durability | Asked By Cynthia Nguyen | Apr 24 16
4 Answers

Best source for long screws?

I'm sure this has been asked and answered before. I need screws in the ~8" range to assemble a rigid insulation/wood sandwich, specifically 5/8" CDX over 6" rigid over 1-1/2" car decking over 4x8 rafters. Many of the screws will land in the 4x8, so could be 8"+, but some will need to land only in the car decking without coming through, and something like 7-1/2" would be ideal. Haven't look anywhere yet, but I know folks here have the answers already.

In General questions | Asked By David Meiland | Apr 23 16
6 Answers

Sourcing High Performance Fiberglass Windows

Hi everyone, I am in Duluth, MN climate zone 7 and am in the process of quoting/sourcing windows. The goal is a net zero house that is relatively small in size at less than 1500 sq. ft. I have one window option for fiberglass from a local dealer (that I know of) and that is Duxton windows.

In Energy efficiency and durability | Asked By Oliver Neumann | Apr 23 16
6 Answers

Ridge Vents - see light?

I was at our new construction home yesterday. It is not yet insulated. I looked up and noticed one small hole where light was coming through. It was at the peak of the roof (runs along the length of the house - it is a ranch). The was no plywood in this area - just synthetic tar paper/shingles could be seen. Our builder said this just where the shingles come together and that no water or anything can get in there. If they put plywood under it, it will wick and rot. He said he could put steel wool there or caulk it but that is not normally what is done. It is normally just left open to vent.

In Building Code Questions | Asked By Carolyn Farrow | Apr 22 16
Register for a free account and join the conversation

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