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!


11 Answers

Carapace Heat-Line freeze protection for off-grid water lines

To answer Malcolm's question (in my other thread about multipoint foundation systems) about how to go about freeze protecting the water and sewer pipes that will be servicing my off grid cabin I think the solution is the "Carapace Heating Water Pipe".

https://heatline.com/carapace-factory-terminated

In Energy efficiency and durability | Asked By Scott Wilson | Mar 12 17
4 Answers

Why am getting so much condensation in my cathedral ceilings? And will it stop?

I am building a home in northern Vermont and just finished the skim coat plaster on the walls and ceilings about 2 weeks ago. Since the plaster has been done I noticed water spots in arbitrary locations but mostly where the walls and ceilings meet and mostly on the south side of the house. I have 2x12 rafters, horizontal 2x4 strapping across the top and just under the plywood sheathing. Then I installed 1x3 strapping in between each rafter from top of wall to the ridge for ventilation.

In General questions | Asked By CPWilcox | Mar 19 17
10 Answers

Cellulose insulation thickness

- Is it o.k to use 3" thick cellulose insulation in 6" or 8" metal stud wall?

It seems that cavity wall should be filled with cellulose insulation on your instruction.
We are not filling cavity to reduce cost and reduce R value inside cavity to locate condensing point outside of metal stud.

- Does it stable during construction and after construction if insulation fills only half of stud wall?

- Is 3" good enough to act as vapor barrier?

Please advise.

Thank you

In General questions | Asked By Hyeon Ju Son | Mar 15 17
5 Answers

New load calculations for new insulated roof?

Greetings all,

we recently had a late season, heavy snowfall, 20 - 30 inches with some drifting.

the local hardware store roof collapsed the day after. the building is >30 years old, and has often seen much more snow than this. [as you see in the photo, most all the snow is on one side but the adjacent uninsulated / unheated building roof is fine]

however, this summer, spray foam insulation [afaik] was directly applied to the underside of the [metal] roof. I do not know what kind or density. this is the first significant snowfall since then.

In General questions | Asked By P HA | Mar 19 17
2 Answers

Trying to make final selections on materials

Need some advice. Got some before from here but can't recall login so posting new thread to ensure I am covered.
- I am in zone 6. Minimum code R-15 required.
- I am finishing a walkout basement.
- Have poured concrete walls with exterior R-5 XPS rigid on walls.
- No history of water, never damp basement
- Was encouraged to do R-13.1 foil faced on interior walls and frame in front. Problem - cannot find foil faced anywhere local that is 2" thick R-13.

Question:
- Can I do R-10 XPS frame in front

In General questions | Asked By ZDude | Mar 16 17
4 Answers

Need sizing advice on a minisplit unit

I installed a Mitsubishi FH12NA in summer of 2014 when they first came out. I live in inland San Diego, and it can get hot, like 10-15 degrees hotter than the coast.

My condo is a studio and is only 420 sq ft. I'm on the upper unit of 2 stories. I face East and South. I have a skylight and dual-pane windows. Building is 1978 construction.

My Mitsubishi is weak. I set the temp and it will barely do anything. I have to set the temp to 61 and manually put the fan on high for it to do anything. Even "powerful" mode is weak.

In General questions | Asked By aypues | Mar 16 17
35 Answers

Inexpensive, efficient HRV?

I just saw the posts about the Panasonic Intelli Balance 100 ERV. Does anybody make a similar HRV? Something with a price point under $1,000, good efficiency and at least 50+cfm airflow? A unit like that would make me reconsider an exhaust-only system.

The closest I've found are the Braun HRV160 ECM units.

--John

In Mechanicals | Asked By John Ranson | Mar 12 17
9 Answers

Basement wall assembly in climate zone 3A

Hi folks,

I'm finishing my homes basement and have been reading on GBA and FHB around the issues and approaches for resilient and efficient assemblies. Below are some facts about my situation:

Climate Zone 3A, new house built in 2016, daylight basement with 3 poured concrete walls and one 2x6 framed, wall height 9'-6".

In Energy efficiency and durability | Asked By Jamie Royal | Mar 19 17
6 Answers

Insufficiently thick exterior foam: Remove, increase, ignore?

Hi there,

I've been reading the articles on GBA about exterior foam and I think mine is too thin to keep the sheathing above the dew point. I'm wondering your opinions as to the best remedy. I'm assuming that removing or increasing the thickness will both be expensive. I believe my wall assembly is risky, but have no evidence it is actually a problem. Given that I'm wondering if the best course of action is to live with it. Here are the details:

- 2 x 4 walls
- .75" polyiso
- Plywood sheathing
- No rain screen
- Stud cavities filled with fiberglass batts

In Energy efficiency and durability | Asked By Jeremiah Breer | Mar 19 17
10 Answers

ERV vs. HRV Efficiency - Humidity Loss Considered?

I've been looking into Heat/Energy Recovery Ventilation and comparing specifications of different models. As we know, HRVs transfer heat and ERVs transfer both heat and humidity to incoming air from outgoing air in cold/dry conditions, and do the reverse in hot/humid conditions.

I was looking at the specs and I couldn't really figure out how the latent recovery of an ERV was being accounted for when compared to the efficiency of an HRV. Perhaps the specs indicate this and I'm just not getting it?

In Mechanicals | Asked By Lance Peters | Mar 15 17
Register for a free account and join the conversation


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