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!

2 Answers

I am building an extension to our existing home and am preparing to insulate the roof

I am building an extension to our existing home and am preparing to insulate the roof which is a low-slope (2:12) cathedral ceiling. I am building the roof using 2 x10 rafters. The roof assembly will be completely sealed.

Many Thanks,
Jean Blain
Gatineau Quebec

In General questions | Asked By Jean Blain | Jun 22 16
5 Answers

Dimple board on a pre-cast concrete basement

I just had a pre-cast basement installed that uses 8000 psi concrete. The majority of the basement is below grade. They told me that I don't have to do any type of water proofing, but since I haven't back-filled yet, I'm going to go ahead and do it anyways for peace of mind. I like the idea of the dimple board membrane except for the fact that you have to nail it into the wall. I don't want to create holes in a wall that is solid! Any ideas if I can install the dimple board without nails?

Thanks in advance!

In Green building techniques | Asked By Andy Spears | Jun 21 16
4 Answers

How to repair the concrete sill under our front door?

We've been having some issues with water leaking into our basement under our front door. We have a metal threshold over a concrete sill, and our front porch is a concrete slab about 4'x6'. There are a number of weatherproofing issues we need to address, but the most urgent is the concrete sill under the door which has been crumbling for a while and presumably is the source of our leak. I've removed the threshold and cleared out most of the loose concrete so I could see what was underneath. Here are a few photos:


In General questions | Asked By Cory Kaufman-Schofield | Jun 16 16
3 Answers

Our insurance company required us to replace the roofs on our rental and on our primary residence

Our insurance co. required us to replace the roofs on our rental, a 1985 Jim Walter home, and our primary residence, a hand-built log cabin. Our question is what is the best ridge vent, and is there any reason to put something like GAF Deckarmor above the new above - roof insulation?

In Green building techniques | Asked By Chip Chandler | Jun 19 16
10 Answers

Vacation home in Utah — How can I cool my home without AC?

Vacation home in Utah. It's vacant. Inside temperature is 92 F, outside temperature is 102. How can I cool the home without AC?

It's a round home in southern Utah with cathedral ceilings. The metal roof is round like parasol. It's vacant. What can I do to get hot air out of the home?

In Energy efficiency and durability | Asked By June Kix | Jun 20 16
2 Answers

How to seal gaps around air conditioner lines?

I'm trying to install a Mini-Split Air Conditioner and looking for suggestions on how to seal the gaps around the lines.

At the place where the lines come through the hole in the wall, there're small gaps between the sleeve and the lines/pipe. I know most contractors don't seal them. But if I really want to seal them, what material should I use here?

Another place I want to seal is the end of duct hide where the lines coming out, I want to seal the opening to keep out small animals/insects.

Thanks ahead!


In Mechanicals | Asked By Tom M | Jun 20 16
5 Answers

How to insulate and soundproof with least emissions/toxicity?

We live in zone 3C, and we're thinking of putting Roxul between studs of interior walls we want sound-proofed along with double sheetrock and Green Glue to bind staggered sheetrock panels together. For external walls we're trying to decide between a denim insulation or Roxul. The house originally had a moisture barrier on the outer side of the studs on the exterior walls and close to the house side in the attic.

In Green products and materials | Asked By Molly Maloney | Jun 16 16
14 Answers

How to insulate cathedral ceiling with standing seam metal roof?

I am in the design phase of building a new home, and having difficulty determining how to construct a cathedral ceiling roof with stand seam metal roof. I have read all the articles on this website for different techniques available, but none of the completely address my concerns.

The architect designed the roof with 2x12 rafters, ply-wood roof sheathing, non-vented, with a standing seam metal roof. Insulated with spray in closed-cell foam. The interior will be painted drywall. There will also be an exposed truss with a collar tie on the interior of the home.

In General questions | Asked By Chad Kotlarz | Jun 17 16
4 Answers

Eave insulation retrofit


I am in the process of renovating a 1940s farmhouse in Westfield, MA and I am running into a bit of a tricky situation regarding existing eaves.

In Green building techniques | Asked By Matthew O'Boyle | Jun 20 16
8 Answers

Through-wall HRVs/ERVs

Looking for thoughts or feedback on the thru-wall HRV's/ERV's - specifically the Lunos e2 system vs. the TwinFresh Comfo RA1-50-2. (I'm reposting this because it got lost in the last barrage of Chinese spam in the Q &A.)

I'm looking for help to determine which one I should use. They need to be installed next week. I have a 850 sq ft apartment that needs to be ventilated.

What I know about the two systems-
They can both work in unison (every 70 seconds or so, they reverse supply and exhaust), during this time the core is regenerating.

In General questions | Asked By Brad Hardie | Jun 18 16
Register for a free account and join the conversation

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