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!

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!

In GBA Pro help | Asked By Kim Howard | Nov 22 16
2 Answers

Questions on insulation and air sealing an attic (new construction)

Questions for all the great contributors to GBA: Building a new home in Zone 5, Philadelphia area.

Framing is done. Roof is finished. I was talking to the insulation sub, and he had some concerns.

My roof is a 4/12 pitch, that is now set up as a ventilated roof, and because of that in most places it's more of a crawl space then a walkable attic, and because of that I do not think it would be possible to add plywood as my air barrier in the attic before drywall and and can lights go in.

He recommends one of 2 options:

In General questions | Asked By Boris Rubinstein | Nov 22 16
3 Answers

Spare the Air days and mechanical ventilation: are filters or cutoffs recommended?

Our local air pollution control district is promoting awareness of days when air pollution is particularly onerous (in our area due to winter still air and wood burning fires). Has anyone analyzed the need for HRV air filters or temporarily turning off mechanical ventilators in these conditions?

In Mechanicals | Asked By Bill Fitler | Nov 21 16
6 Answers

Side opening on a shrouded industrial fan

I need to redirect exhaust flow 90 degrees. Rather than fabricating ducting offsets from a plenum box fitted to the exhaust opening, I am considering doing away with the plenum by blocking off the fans exhaust opening, and creating a side opening in line with the fan blade tips. This will allow straight line ducting. Will this reduce the fans efficiency.

In General questions | Asked By Mike Lish | Nov 19 16
9 Answers

Insulating a Cape Cod attic

I could use some guidance on insulating my 1.5 story Cape Cod that I’ve been living in since the beginning of last year. I suffer from the same problems as most Cape Cod owners - the upstairs is very hot in the summer and very cold in the winter.

In General questions | Asked By Greg H | Nov 21 16
4 Answers

How can I make my exterior walls more energy efficient?

I would like to make the exterior walls of my home more energy efficient. My home is, as shown on your climate zone map, in zone 4a. It is about 1 hour south of St. Louis on the Illinois side. I currently have a 100 + year old home with no insulation in the 2x4 stud bay. The home currently has the original shingle siding, then a layer of 1/2 inch xps, and finally vinyl siding. Removing the siding is not an option in my foreseen budgeting plans so I would like to add to the interior of the home.

In Energy efficiency and durability | Asked By anthony smithe | Nov 21 16
3 Answers

PV cost update (nothern NJ, near NYC):

We just installed a 9.6 kW PV system on our PHIUS-certified passivhaus in northern NJ.

I was the installer of record. I hired a licensed electrician who has an experienced PV installer crew.

It has 30 320W LG panels, a SolarEdge 10 kW inverter and 30 of their Optimizers. We used the QuickRack panel mount system - no rails.

The materials cost roughly $18,000. The installation cost around $7200.

That works out to around $2.66 per watt.

When I priced the same installation from the large installer companies, they quoted a bit more than $4 per watt.

In PassivHaus | Asked By Len Moskowitz | Nov 17 16
2 Answers

EIFS and WRB questions

We are at the design phase of our new home. We live in a Nicosia, Cyprus and we enjoy a Mediterranean climate with mild winters and hot summers with only a few inches of rain per year, and relative long sunny periods between wetting events (rain). Our design calls for large overhangs (4-5 feet) around most of the building, mainly for shading purposes during the summer.

In Energy efficiency and durability | Asked By Antonis Antoniou | Nov 21 16
0 Answers

Open a side exhaust port in a shrouded industrial fan

Editor's note: This question was accidentally posted twice. Here is a link to the page where the question was first posted: Side opening on a shrouded industrial fan. All comments on this question should be posted on that thread.

In Mechanicals | Asked By Mike Lish | Nov 22 16
4 Answers

Difficult building inspector

Needless to say our Building Inspector is real charmer, and on top of that is very unfamiliar with energy smart building techniques. We are putting up 3" of Roxul comfortboard followed by 1x4 furring strips and Hardiplank fiber cement siding. The inspector wants proof from James Hardie that this method is acceptable and safe. We sent him this document from Roxul where they had Building Science Corp conduct a study on deflection using our exact cladding system.


In Building Code Questions | Asked By Brian W | Nov 21 16
Register for a free account and join the conversation

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