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

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2 Answers
Help me determine my wall's dew point

I’ve spent hours researching this site (which is great by the way) to try and determine what the dew point would be in a proposed wall assembly-(flash and fill). I’ve read the blog mentioning Joe Lstiburek’s approach which seems to be based more so off a wall system with exterior insulation board. I also found a table stating in need 2” of closed cell insul. So I’m a little confused.

In General questions | Asked By v a | May 2 13
20 Answers
R-value vs. thermal mass

Hi GBA,

In GBA Pro help | Asked By David Epley | Jan 26 12
8 Answers
SIP home with 2 air handlers for open space floor plan?

Plans / pics are attached

Exterior walls are SIPs R-24 with 1-1/2" EPS stucco
Center 'bumpout" is typical 6-9 stick with 3" EPS (interior to be sprayed)

WIndows are Integrity Low E3

window wall south facing

Proper way to heat and cool

We are in the process of building a very open floor plan home with catheral ceilings in CT (zone 5) with 2 levels.

Main level - 9-17' ceilling heights
Lower Level ( Walkout) has radiant in an exposed slab and footings over 2"EPS.

In Mechanicals | Asked By Chris van Wilgen | Feb 5 13
1 Answer
What is the best way to plaster an exterior wall insulated with straw bales?

We are wondering if it is wise to plaster directly on the 2" mortar that protects the straw bales or if we should use furring and plywood on which we would fix a screen to put the plaster on. It would add an air gap between so that the wall could dry better but we don't know if it is worth it.

What do the experts think?

In Green building techniques | Asked By Serge Bedard | May 1 13
1 Answer
Link to Building America study on exterior insulation retrofits

Here is a link to a recently published Building America study on several exterior insulation retrofit projects:
Project Overcoat — An Exploration of Exterior Insulation Strategies for 1½-Story Roof Applications in Cold Climates

In Green building techniques | Asked By j chesnut | May 1 13
5 Answers
Thermal break/insulate between concrete slab and slate

Hi, looking for a way to add some insulation between slate and a slab. I just did a small area about 2' x 5' used some hardiboard to raise it up a bit, but man is it cold! I might tear it up if i can warm it up somehow.
I also will be doing about 100sqft in addition

I have 1" max that I can add to the thickness of the mortar and slate.

any ideas?

Thanks!

In General questions | Asked By mark kessler | Apr 19 13
8 Answers
Wall design in renovation - with moisture issues

Sorry in advance for the long question. it seems important to establish the full context because i've been unable to match my circumstances to the thousands of articles i've read here and other places.

Zone 5a/6a border (Hudson valley, ny) 1959 slab on grade, standard 2x4 framing single story house.

It's cut deeply into the hill, and the entire back of the house is 2 feet away from a 3-5 ft high retaining wall. ugh.

The house is environmentally almost a walk in basement. high humidity levels, and, no surprise, mold. solving the moisture will hopefully help the mold issues.

In General questions | Asked By kikiyut 555 | Apr 30 13
5 Answers
Spiders, flies, ladybugs, hornets and beetles

I have just installed both range and bath vent fans and 4 passive air inlets. We live in big orchard and farm country where the flying and crawling insect populations are often swarming. When they hatch they can reach infestation levels.

None of the fan and make up air products have adequate protection and none have exterior (intake side) filters. The Panasonic and Aldes products are particularly weak in this area.

In Mechanicals | Asked By Oak Orchard | Apr 30 13
2 Answers
Insulating brick from the exterior

I am renovating an end-of-group brick rowhome in Maryland. The home was built in 1914 and has 8" masonry load bearing walls. The owner is interested in exposing the old masonry walls on all (3) exterior sides of the building. To do this I will have to insulate from the exterior and install new cladding. I am not confident in installing 4" or so of rigid insulation on the old masonry, mostly due to cost/ performance of fasteners that long into the old masonry. The rainscreen and new cladding will also be relying on the same type of fastener.

In Green building techniques | Asked By Charles Chiampou | Apr 27 13
8 Answers
Heat loss calculus: solar heated siding and air space

I would like to discuss about the implications on heat loss calculations of temperature of exterior finish and its different layers (notably air space) and its effect on the delta T .

I have not found much info using the search, rather some mentions about the effect etc.. Maybe I am not using the correct terms to look it up?

So basically, when we are calculating the heat loss of an area using HDD or simply a specific time delta T, how is it affected?

A dark grey finish with a 3/4 air space under it should get pretty hot during day time when the sun is shining high...

In General questions | Asked By Jin Kazama | Apr 24 13
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