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2 Answers

Basement Insulation Question

Hello:

I'm building a house in Zone 5 (southern CT). The house will have a full basement with spray on waterproofing. There is no sub-slab foam. The builder budgeted for 2" of XPS (with dimpled moisture facing) on the sub-grade exterior of the foundation walls, but NOT the above grade portions. There will be a footing drain running to daylight and a shed water system to catch storm water running off of our house (2 foot overhangs; no gutters). The soil is sandy loam and drains well.

Asked By Adam S | Jan 20 17
2 Answers

Flashing tape for roof decking

We build houses for a Habitat for Humanity affiliate in a hurricane prone area along the Texas Gulf coast.
At a program on the FORTIFIED building certification, we saw something that intrigued us. They suggested taping the seams of the roof decking. This would prevent water damage in the event that the shingles were blown off in a wind storm. We started using such materials on the last few houses.

Asked By Steve Young | Jan 19 17
6 Answers

Thermal breaks for window bucks in double stud walls

We'll be buliding double stud walls for a new house, with the inner wall being structural (the outer wall will consist of modified Larsen trusses). Total wall thickness will be around 16" and windows will be "in-betweenies". This will be my first double-stud wall house and I'm working in the wall details trying to minimze thermal bridging.

Asked By Chris Chenier | Jan 18 17
3 Answers

How thick a layer of closed cell spray foam under roof deck?

Our roof has 4" of rigid board closed cell foam with OSB (Atlas Nailbase) installed above the roof deck, but the seams between the sheets of foam were not sealed, as one can see in the attached picture. For those areas I can access, I started spraying closed cell foam on the underside of the roof deck - how thick a layer of spray foam under the roof deck do I need to have for reasonable insurance against moisture condensation at the seams of the Atlas OSB??

Asked By Jim Berry | Jan 18 17
2 Answers

Vapor Barrier on top of SIP floor?

We are working out the details for the construction of our new house in the Pacific Northwest. Our architect and structural engineer have specified a 9 1/4" SIP floor for the 1st floor. Since we will be building in a flood zone, our foundation will be an open design with concrete columns extending from a mat foundation. Horizontal beams will sit on top of the columns and the SIP panels will sit on top of the beams. The structural engineer has specified a factory treatment of "bluewood" preservative to the bottom face of the SIP panels.

Asked By Kevin Camfield | Jan 17 17
1 Answer

How should moisture/vapor wetting and drying be considered in this situation?

Details:
- Climate Zone 6, Marine setting
- Stand alone garage(1970's) to be converted to an overflow guest house w/ full bath no kitchen.
- Guest house to be used in summer only.
- Existing structure on a floating slab w/ no vapor barrier beneath, sitting poorly drained soils.
- 20' by 16' area w/ cathedral ceilings, 2x4 walls and 2x8 rafters
- 20 mil vapor barrier to be installed over slab (seams taped), may not be able to extend under existing perimeter walls.
-2x4 sleepers laid flat over 20 mil VB
-1 1/2" xps fitted between sleepers

Asked By geoff summa | Jan 16 17
5 Answers

Mineral Wool R-value by temperature

Does anyone know if there is any information available that shows the performance of mineral/rock wool by temperature?

Buildingscience.com has this for polyiso:
https://buildingscience.com/documents/information-sheets/info-502-temper...

I am wondering if there is something similar for mineral wool.

A few other links I have found -
http://www.greenbuildingadvisor.com/blogs/dept/musings/bold-attempt-slay...
http://www.energyvanguard.com/blog/59419/Big-News-The-R-Value-of-Insulat...

Asked By Nathan Scaglione | Jan 15 17
8 Answers

Vapor Retarders/Double Air Barriers

May I ask to ensure we haven't missed anything in thoughts on building our home. I was under the impression we would use Closed Cell Spray foam for the entire assembly, but my husband is now thinking Open Cell for the above grade walls. Will these assemblies work?

Unvented Cathedral Ceiling
Metal Roof/Air Gap/Asphalt Felt/ZIP Roof Sheathing/Closed Cell (still negotiating the amount)/Back Venting/USG Ultra Light Drywall

Vented Unconditioned Ceiling

Asked By Bridget Lamberson | Jan 15 17
0 Answers

Cold Access Room - Gaps in Air Barrier

** Re-posting to the proper Q&A category **

Hi -

Asked By Joe Duchek | Jan 16 17
5 Answers

What is correct installation of rigid foam board on roof, at seams of each panel?

What is the correct means to seal the seams between foam board applied on top of roof sheathing? What is the impact of incorrect sealing? Background: we contracted with a roofer to apply 4" of Atlas nailbase on top of the roof sheathing, before shingling. I happened to look at the roof on a recent cold morning and noticed gridmarks on the roof, indicating areas where frost had either melted, or had not formed, due to heat loss between the seams of the nailbase. I would think if the seams had been sealed correctly there would be no visible frost lines.

Asked By Jim Berry | Jan 11 17
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