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

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9 Answers
Cost effective exterior wall construction.

In exploring options for a cost effective R-40 exterior wall in a cold climate (Western Massachusetts), I am left scratching my head. As a residential designer, I have researched Building Science's website and their High R wall systems, where multiple layers of rigid insulation and a thermal break is their obvious choice. However, when clients want shingled siding and decorative trim, I want the sheathing on the exterior face of the rigid for consistent nailing. In addition, my structural engineer wants the sheathing directly nailed to the studs for shear (100 mph wind speed).

In Green building techniques | Asked By Jon Wyman | Feb 1 10
4 Answers
Combination DHW and Space Heating

I'm interested in learning regarding the feasibility and advisability of using a hybrid "small tank" condensing or tankless condensing hot water heater to provide both DHW and space heating for new construction in a heating climate. Examples include Navien America 180/210/240 (EF .98-.95), Eternal GU195 (EF .96), Takagi TH2 (EF .93), Rinnai RC98HP (EF .93), Quietside ODW199 (EF .92), or Noritz NCC199 (EF .92).

In Mechanicals | Asked By Jan Juran | Feb 8 10
6 Answers
Software for Builders

When I was getting out of building and remodeling, I had a website with password-protected places for customers to log in and view documents/photos related to their jobs. I was too cheap to buy estimating software, so I made spreadsheets to estimate things like lumber and drywall. There was no SketchUp, so I drew everything by hand. One builder I know used to set up a fax machine on the job site so the design team could fax detail drawings over.

What kinds of software do you GBA members use to design/build/remodel homes?

Estimating?
Project management?
CAD?
Accounting?

In General questions | Asked By Daniel Morrison | Feb 6 10
1 Answer
IN LEED for homes SS2.5 and WE2.3 can I get all points if I have no irrigation

I have a landscape design which includes undisturbed drought tolerant shrubs that were on the site before I started building and the grass that I put in is drought tolerant short red fescue. I am not installing an irrigation system. Shouldn't I automatically get 10 pts for this?

In Green building techniques | Asked By Bill Potter | Dec 17 09
29 Answers
AFFORDABLE Low Energy

Forget about Spray Foam
Forget about Conditioned Attics
Forget about Vaulted Ceilings

Provide a Simple(and rigid) Air Control Layer
Add Ventilation
Add a Thermal Control Layer
Add Cladding Structure and Roof Structure
Add Replaceable windows and doors and Sacrificial Claddings

Cladding structure can be as simple as furring strips

In Energy efficiency and durability | Asked By John Brooks | Feb 5 10
10 Answers
Drying to interior and paint

Hello all,
I've been learning all the Building science I can lately, and of course, that leads to questions! Hope folks here can entertain a few.
Here is one question I'd love some feedback on.
Consider a New England home that is to get outsulation, or exterior foam insulation in retrofit, or new construction. Almost all outsulation details create a vapor impermeable surface, and thus the wall is then expected to be able to dry to the interior.
How many coats of paint can a gypsum board wall take before the perm rating gets so low as to be risky?

In General questions | Asked By Nathaniel | Feb 3 10
40 Answers
What is the best wall construction in North Carolina?

I have clients wanting to build a LEED (hopefully Silver) home in NC and I keep going around about the best wall system to use that is energy efficient, cost effective and structurally sound. We (builder, structural engineer and I) have decided on a 2x4, 24" O.C. staggered wall design that is off set 12" between studs and 2" front to back. Top/sill plates are 2x6's. 5/8" sheetrock on interior, 1/2" OSB exterior with a double layer of TYVEK DrainWrap taped and sealed then spider lath and stucco finish (looking for low maintenance finish).

In Green building techniques | Asked By Sophie Piesse | Jan 26 10
3 Answers
How to make my 1966 home more thermally efficient?

I am retired and faced with very large heating bills. The weather in NJ has been quite cold and snowy for us. Our home was contractor built
in 1966. 2x4 walls with 3" on insulation. The windows are wood but not as tight as today, but the stroms windows leak to a point that we get snow
between them and the window. The house is a colonial salt box, The front is one storey, two stories in the rear. There was no insulation in the frount. I have tried to put some over the years but not sure how much good it really does.

With limited funds what is your guess as to the place to start.

In Energy efficiency and durability | Asked By Tom Spang | Feb 8 10
6 Answers
Contrast plywood window RO extensions with other method?

Hello folks,
I wonder if I could get some discussion on the pros and cons of two window methods with outsulation.
I've seen the plywood RO extenders used.
Contrast that with:
(for a 2 in exterior detail) 1 layer of foam right to window RO, with the RO then surrounded with 1x 3+/- as an attachment surface for the window flange. Second inch of foam buts up to the wood around the RO.
Similar situation for thicker foam I suppose.
Thanks!
Nathaniel

In Green building techniques | Asked By Nathaniel | Feb 3 10
19 Answers
HERS ratings & kBtu/sf/yr

Is there a direct relationship between HERS ratings and actual energy use, such as kBtus/sf/yr? Energy Star is gaining traction and making incrememtal improvements to their standards. Stretch Codes in Massachussetts pretty much make Energy Star the default route to comply. So the HERS rating is gaining traction for consumers. Its based on a scale with "0" being a Zero Net Energy Home, and 100 being a code-based home from 2003 or some such year. But I wonder how the HERS rating is related to energy use per square foot per year.

In Energy efficiency and durability | Asked By Chris Vlcek | Jan 29 10
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