Community: General questions

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!


3 Answers

12v dc voltage system to run "micro sized" hydronic heating system

Hi Folks

My name is Bill and i would like to heat a small sleeping area in a mobile off the grid environment hydronically.

there are two ways i think may work but thought i would ask the more experienced group here to get some direction...

1st thought is to source a 12v controller that could run a 12v 4 way mix valve and also a very small 12v circulation pump to circulate water at a rate of less than .25 GPM

Asked By freewillieklr | Mar 23 17
2 Answers

Closed Cell Spray Foam Basement Insulation Concerns

Hi everyone, any insight you can provide is much appreciated.

I am currently preparing to install spray foam (4in of 2lb closed cell) in my basement.
The plan is to insulate the full basement walls (concrete + pony wall section), plus the sill plate and rim joist pockets.

A couple of questions/concerns I had prior to going ahead with the install..

Asked By user-6803198 | Mar 23 17
7 Answers

Tankless water heater AFTER my tank?

I have a Rheem Marathon and do not want to replace it. However, we occasionally run out of hot water when we have company. This is rare, but inconvenient. Here is my quandry:

Asked By Emil Mackey | Mar 21 17
12 Answers

Metal siding — window head flashing detail

OK this keeps resurfacing so I thought I would see what others have come up with. When using metal siding (corrugated or sim.) dealing with the window head always seems to be a bit of a conundrum.Typically I see a piece of "J" flash utilized. But this usually points up, which may conceal the cut of the cladding panel, but consequently also catches water. Seems wrong. I have been trying to come up with an alternative and drew the attached, but surely someone more intelligent than I must have devised a better solution for this issue ?

Asked By Erik Lobeck | Mar 21 17
5 Answers

How to detect a roof leak after having the underside of the roof deck sprayed with closed-cell foam?

I live in Buffalo, NY, and am renovating a Cape Cod style home. The interior is completely gutted and had a roof tear off and GAF system installed with no ventilation, with the plans for having the deck sprayed with closed cell. I had a question that no one up here can answer...

As the roof fails or if there is some sort of damage, how will I know if the underside is 100% sealed? My fear is the water will rot the rood substructure and hold mold. Is there any way to create a path for any potential leaks to follow??

Asked By cheezlo | Mar 22 17
1 Answer

Timber vs concrete uppermost ceiling

Price not being a factor, does either of these options have any significant advantages or disadvantages over another?

I'm building a 2 story brick and concrete house, but am considering of going with timber ceiling under the roof (which could also end up being flat roof).

The local price will be the deciding factor, but only if there are no serious drawbacks to the timber construction.

So, what gives, if anything?

Sound insulation should not be an issue since it's uppermost?
There is not much difference in thermal insulation?

Asked By davor radman | Mar 23 17
3 Answers

Exterior foam and Roxul batt on a reno

Have a client who has an older house he just purchased . Scarsdale NY . He intends to put 1" rigid foam outboard of the sheathing with Tyvek behind and 1x strapping to attach siding .

Interior first floor walls are 2 x 6 , second and third floor are 2 x 4 . Question 1 is what R value Roxul should he use in the 2 different wall assemblies ?

Second question is , is Tyvek the right product to use as the only barrier between the sheathing and exterior ?

Asked By Richard McGrath | Mar 22 17
11 Answers

Do magic boxes distribute loads for ductless units?

For my pretty good home I am building( 2150 sq.ft. Zone 5 northern ct. near Sturbridge mass) I have recently got a quote back for mini splits. 5 heads 2 outdoor units Mitzi. Hyper heat. The contractor is at 17k installed. Diamond dealer. He has one head in each bedroom and 2 on the open floor plan. I am curious if there is a way to quantify how much a ducted ventilation system mixes the air around the home? Would a Minotair or cerv balance out the heating and cooling requiring more like 2 or 3 heads?

Asked By Scott Mangold | Mar 20 17
11 Answers

Sound attenuation between floors

I am constructing a floor assembly between a 1st and 2nd floor and may not be able to build up a deep floor assembly due to exposed ceiling timber joists (and the small footprint of my structure). I am considering using 2 courses of Advantec (subfloor) material with perhaps a mass loaded vinyl material in between the subfloor material.

I was wondering if anyone else has constructed a floor assembly that might reduce some of the sound transfer without resorting to a deep floor framed system. Has anyone had success solving this problem?

Asked By John Brown | Mar 15 17
2 Answers

How do I resolve summertime heat issues and winter ice dam issues in a kneewall attic bedroom w/ a blocked /insulated ridgevent?

Hello, I've really enjoyed your site this winter while researching ice dam fixes and then consequently many other building designs and fixes.

I live in northwest Montana in an old house framed with 2x4's in a smaller house with an attic that's been built out. Our house has a valley on the east and on the west side, we have knee walls upstairs. We are going to get our roof redone this summer with snow and ice shield to the ridgetop.

Asked By shmac | Mar 22 17
Register for a free account and join the conversation


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