Q&A: A Forum for Green Building Experts and Beginners

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3 Answers
Polystyrene insulation between studs and plywood sheathing?

Putting an addition on my home...thinking about upgrading insulation package to include 1" polystyrene between 2"x6" wood wall studs and 1/2" plywood sheathing (as oppossed to the much used polystyrene over sheathing) in order to increase r-value and to act as a thermal barrier. Ive researched this and havent found much if any information on putting the polystyrene under the sheathing, but in an email exchange with Paul Fissette, professor at UMass/Amherst he said that my idea would be work. I initially had thought of using 1/2" polyiso w/foil facing, but Dr.

In Energy efficiency and durability | Asked By jroy | Mar 25 10
8 Answers
Green Permits

I learned today that a couple of builders I work with "volunteered" me to meet with one of our local Codes Departments next week to explain, and possibly help develop the process for, a streamlined Green Permitting Process. While there is good information here in the Code Green Blog, I am curious if anyone else has been through this process with their Codes Department? If so, I would appreciate any comments or suggestions related to your experience.

In Building Code Questions | Asked By Grant Dorris | Feb 4 10
19 Answers
Vapor-resistant layer - VB film or ADA?

We are building a super-insulated house in the northeast <3" poly-iso on the exterior, 2x6s @ 24" OC with cellulose fill, spray foam at the box sills>. We specified an air-tight-drywall-approach, with the latex paint acting as the vapor-resistant layer. But the insulator installed a 6mil vapor barrier over the netting. My understanding is that an additional VB layer prevents the wall cavity from drying to the inside. Should we tear out the VB and go with the ADA or leave it in and skip the ADA?

In Green building techniques | Asked By Chris Vlcek | Mar 21 10
2 Answers
Does anyone have experience with roll-on or spray-on weather barriers instead of housewrap?

I am building a tight house with 6" SIPs panels and I have been investigating the pros and cons to roll-on or spray-on weather barriers (with little success). The main advantage is a consistent air barrier. Are there any down sides? Does it really provide a drainage plane comparable to a housewrap? I have been looking in particular at Tremco's EnviroDri. Perm rating is a 12. Does the asphalt base or the other chemicals involved cause any additional issues - possibly for air quality indoors? Thanks in advance for any help.

In Energy efficiency and durability | Asked By Brian Burkes | Mar 23 10
20 Answers
Sub pump with 2" discharge pipe clogging up from silt clay in the water.

I have a 10'deep x 5' diameter pre-cast concrete man hole with two pumps alternating for my 6" footing drains located outside of the house. This is a new construction house. I put down 12" inches of trap rock in the basement floor with 4" perforated pipe and grid pattern tied into my six-inch footing drains. I also put down filter fabric before the trap rock went down and over the 6"perforated pipe. What is happening is a orange colored clay is sticking on the inside wall of the 2" pipe closing it down to 1"on the inside walls. Seems like every six months this occurs.

In GBA Pro help | Asked By Peter Fusaro | Mar 12 10
1 Answer
Products with Sodium Per Carbonate

I was looking for a green deck wash product recently and was offered a product containing Sodium Per Carbonate. Is this product with this chemical makeup really green?

In Green products and materials | Asked By Rod MacKenzie | Mar 22 10
8 Answers
Using aluminum flashing as radiant barrier

As part of a bathroom remodel I asked the contractor to install a radiant barrier inside the wall behind a radiator. I had envisioned the use of the foil type material, but instead he used a sheet of aluminum flashing. I haven't yet determined whether he left an air gap behind the flashing, but if he did, will the flashing be at all effective? I assume that without the air gap it would be ineffective.

In Energy efficiency and durability | Asked By John Sullivan | Mar 12 10
1 Answer
Insulating a 150-year-old house

I am gutting a 150 year old balloon-frame house in Vermont with board sheathing, I am going to add a second row of studs or 1 1/2" horizontal strapping to the walls, blow in cellulose, and use airtight drywall. Should I do anything to seal the cold side of the wall? Tyvek on the inside of the sheathing?

In Energy efficiency and durability | Asked By will goodwin | Mar 21 10
3 Answers
How much weight will a 2 by 4 roof/ceiling truss take?

I have a manufactured home and want to add insulation and replace the ceiling.

In General questions | Asked By charles kilpatrick | Mar 21 10
13 Answers
Foam on retrofit 2-wythe brick mass walls?

Hi, i live in Baltimore. I am thinking of adding insulation to my 2 story + basement house. It was built in 1938. It has a double layer of brick for external wall support (total 8 inches). This is not veneer cladding but a mass wall, supporting the roof. I think originally there may have been plaster applied to the brick on the inside. However, the walls sound hollow when I knock on them, and someone has suggested the house may have been retrofitted in the past with perhaps some furring and a layer of drywall. In the unfinished basement, this brick is exposed.

In Green building techniques | Asked By Richard | Mar 17 10
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