Community: GBA Pro help

Q & A Instructions

[Click map to enlarge]

The 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!

5 Answers

Interior vapor barrier for old house?

I have a hundred plus year old building (originally single-family, converted to three-family) on Long Island (Zone 4A) that has a mix of 2x4 framing (balloon & other), with 1" nominal (minimum 3/4", to 7/8") tongue & grove wood sheathing underneath clapboard that's covered with aluminum siding.
We're going to remove the clapboard & aluminum sidings, keep the sheathing and cover it with Tyvek, 1" foam (polyiso or XPS) and vinyl siding.

Asked By Robert Fontanetta | Mar 4 16
4 Answers

Down South cathedral ceiling insulation confusion

A little bit confused most everything I find is for northern climates and the little info I have found for my climate seems to contradict one another. Need some help to figure this out.

I'm in zone 2a, central Florida. The house is an octagon in an octagon with the main floor roof about halfway up the 2nd floor/loft walls, sitting on top of the garage/basement. Except for the 3 bedrooms and baths the entire house has cathedral ceilings covered in cedar planks.

Asked By Gerald DeArman | Mar 4 16
1 Answer

Adding insulation

My wood frame Wisconsin home was built in 1894. Over the years I have been making improvements.
When I take down a plaster and lath wall, I've been putting in insulation and 4-6 mil plastic to tighten things up prior to drywall. I found that upstairs, where the roof meets the outer walls there exists an opening directly to the outside. I assume it's designed that way to circulate air. Is it OK to be sealing that up like I have been doing? Should I be putting in ventilation panels in those spots up to the attic space?

Asked By Jon Reiser | Feb 25 16
4 Answers

Tolerances for gravel supporting foam below slab?

How critical is the flatness of the gravel bed below 2" sub-slab foam?

Asked By David McNeely | Feb 21 16
1 Answer

Suspended concrete slab on OSB/joist floor

We are building a home with a 3" regular concrete slab (not lightweight) with embedded radiant heat poured over a traditional TJI and 3/4" T&G floor. The floor is engineered to hold the weight of the concrete of course. This will be the finished floor.

My question is, do we need to put any type of underlayment on top of the OSB (under the slab) before the pour. We want to be sure the concrete can dry appropriately. Do we just tape the seams of the OSB to keep the pour from leaking into the lower level or does it need a barrier of some sort?

Asked By Steve Wilson | Feb 20 16
4 Answers

Interesting dilemma with mounted light fixture

Hi everyone,

I'm a novice to most things home improvement, so bear with me on this potentially ridiculous question. :)

I was trying to remove a hanging light fixture in the kitchen and mount a new one, and I noticed when I got the current fixture lowered, the cord of the light was attached to a slightly recessed black adapter within the mounting bracket that read safe switch/not interchangeable with other lamps (if not descriptive enough, I can provide a picture.)

Asked By Ryan Lambert | Feb 19 16
34 Answers

Roxul board used in basement as insulation against concrete wall?

I just watched a mike Holmes episode. He was building out a basement for bar, home theater, gym, etc. against all the walls he used roxul board as an insulation barrier then the walls were framed. I've read where Martin Holliday advised against this practice. Who's right? It makes more sense to use foam or foam board as it won't hold water. Thanks for any clarification on this topic.

Asked By tim gabriel | Mar 5 15
53 Answers

Best way to fix insulation problem in cathedral ceiling? Please help!

I built my chalet about 8 yrs ago and was up in the attic and noticed black water stains (probably mold).
after many days and night researching what was wrong, i believe my issue is insulation and air leakage.
i have called all the insulation and roofing businesses (not many in this area) and each says its the others issue.

this site has been the most informative, but i cant seem to find any article or videos on how to add or change insulation in a cathedral ceiling after construction has been done.

Asked By Aaron H | Jan 31 16
4 Answers

Do I need to install rigid insulation in the bottom of a walk-in refrigerator before I install tile?

I am being hired to remove the failing metal floor and install quarry tile in the bottom of a commercial walk in refrigerator. The existing floor has 4" of insulation, then plywood and then metal floor on top of the wood. I believe the existing insulation is in very poor condition and possibly wet and I am planning to remove all of it. This is in a restauraunt in southeren California which is on the second floor of a commercial building where there is a structural slab as the foundation and there is occupied space on the first floor below.

Asked By Jim Jelinski | Feb 10 16
8 Answers

Leaky Ductwork in Basement

After getting a very poorly rated energy audit from our electric company, I'm working diligently to get our house more air tight. Seeing lots of posts about HVAC equipment, I'm thinking ours is a little lacking. It is 5 years old, the furnace is 95% efficient. But, the black tape is falling off and according to infrared, it is leaking. I've attached several pictures and also infrared pictures. We are in zone 5 (NW MO). It is 20 degrees outside and our basement walls are 47 and 53 at the frost line.

Asked By Becky Parrish | Feb 9 16
Register for a free account and join the conversation

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