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20 Answers

Heat Transfer Plates for Radiant heat under floor joists

While everyone can agree on certain aspects of radiant heat systems e.g., most of the time PEX tubing is the right choice, there is a lot of divergence of opinion on the use of aluminum heat transfer plates in under joist installations over untreated living space. The closest I've been able to come to a reliable answer is a study done that seems to suggest that they are a good idea (ASHRAE Research Project 1036 "Develop Simplified Methodology to Determine Heat Transfer Design Impacts Associated with Common Installation Alternatives for Radiant Conduit")

In General questions | Asked By Michael schlee | Jan 4 12
5 Answers

Geothermal or AirSource Heat Pump

I'm trying to make a decision on which type unit to go with. House is approximately 1665 sq foot ranch with equivalent walkout (daylight basement). See plan here: http://houseplans.co/house-plans/1236/

In Mechanicals | Asked By Aron Robinson | Nov 24 12
6 Answers

How can I prevent my roof from sweating?

Hey guys... I want to thank you in advance for your time and sharing your experience and professionalism. I live in Vermont. Upstairs, my roof is part of the wall structure. Last year, my roof sweat like crazy. We insatalled vinal in the eaves and proper vented the roof to the attic space. My issue seems to be in the valleys. Since they dont stretch to the eaves, I am unsure how to get ventilation. Right now, there is proper vent in there with fiberglass insulation below. As you can well imagine, the venting isn't cut perfectly and the insulation butts up tight. Will this work?

In GBA Pro help | Asked By Aaron Chapdelaine | Nov 27 12
4 Answers

How do you reconcile continuous insulation requirements with rated assembly requirements?

The application is multifamily construction. We have energy requirements stipulating continuous R-3 insulation, in addition to required cavity insulation. We also have rated exterior wall assembly requirements.

I have not found any UL or GA assemblies that work, nor have I found any SIS product that has been UL tested.

In Building Code Questions | Asked By david nofsinger | Nov 27 12
23 Answers

How bad is it to use polyiso on the deck and spray foam on the bottom?

I am having my "flat" roof EPDM rubber roof replaced, which right now is only insulated by whatever amount of polyiso foam is on top of the deck. The rafter cavities are empty and the ends, only, of those cavities is currently stuffed with fiberglass batts.

In Energy efficiency and durability | Asked By Brian Winke | Oct 25 12
6 Answers

SIP on top of ICF

I am designing a house using 8 inch ICF foundation walls and a ten inch SIP on top of the walls. The SIPs will be 12' high. The main weight in a SIP is in the strand board skins so I want both of these skins to be over concrete even though they sit on top of a 1.5" thick sill plate.

My design is attached. My builder is concerned that if the slab settles different to the ICF wall there will be some imbalance of weight. To try and counter this I have made a ledge on the ICF wall for the slab to sit on.

Does anyone see potential problems or a better way to mount this SIP on this ICF?

In GBA Pro help | Asked By Stephen Carlton | Nov 27 12
4 Answers

Double-stud wall construction filled with Roxul

I am in discussions with a contractor on how to insulate a staggered double-stud wall, 2x6 on the outside and 2x4 on the inside.

We can save a fair amount of money by filling each stud bay with Roxul and a layer of poly between the studs. I see this detail all the time with blown-in cellulose. What is the downside to 2 layers of Roxul in a staggered stud wall assembly?

In Green building techniques | Asked By David Matero | Nov 27 12
1 Answer

Insulating a spalling foundation

A portion of a near--term retrofit to my 1925 cape calls for insulating the poured foundation walls. Before hiding any foundation issues with 3" of spray foam, I'd like to solicit for some guidance. Here are some foundation facts not already mentioned:

77" total inside height
8" thick
22" exposed above grade on East side
33" exposed on West
Moderate spalling along all lower foundation edges to ~8" high

In Energy efficiency and durability | Asked By John McMurry | Nov 26 12
7 Answers

Tankless water heater - attic or crawlspace?

Climate zone 5 -- Indianapolis, Indiana. I live in a very small house, 1000 sq ft., so I want to free up the large closet that currently holds the furnace and tanked water heater, both natural gas. I'm chucking the ducted hvac system in favor of a ductless mini-split and converting the tank water heater to tankless. I want to put the new water heater in either the attic or crawlspace. Is one location preferrable? Do I need to purchase a unit designed for outdoor use?

My goal is to move the laundry out of a bedroom and into that large closet space.

In General questions | Asked By David Martin | Nov 25 12
8 Answers

Effective Energy Star dishwasher choices?

Hello GBA community:
I often get questions involving dishwasher selections. Traditionally, my advice was, naturally, Energy Star. More recently, I've questioned this general advice given the user experiences that I've witnessed. The problem statement is thus: I'm seeing wasteful dishwashing practices in all of the homes that I'm involved with. The homeowners all have some brand of high-end, Energy Star rated dishwashers, and all of them pre-wash their dishes because the dishwasher just doesn't do a sufficient job at washing dishes by itself.

In Green products and materials | Asked By Lucas Morton | Nov 20 12
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