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7 Answers

Design for sealing open dirt floor crawl space

Hi I have a 28' x 30' crawl space that has a dirt floor and CMU walls. Ceiling of it is exposed with pipes and wires running around everywhere. I live in western Colorado so it's dry most of the year. I get some ground dampness, but no flooding, during a few months of summer when my hillside gets saturated in places from a natural spring in the rock ridge above me. I have pipes outside of the crawlspace that provide drainage and I keep the soil sloped away from the home walls. My adjacent slab walkout basement has 4" gravel, 2" sand, and vapor barrier under the slab.

In Energy efficiency and durability | Asked By Andy Nels | Jan 21 16
1 Answer

Panasonic WhisperComfort ERV - not necessarily a "spot" ERV anymore!

Corbett Lunsford just posted the first of a series of videos on how to convert a Panasonic WhisperComfort "spot" ERV into a ducted ERV. Apparently this setup was described to him by Panasonic engineers, so it has some legitimacy behind it.


This video doesn't contain all of the details, but more videos will follow (you can subscribe and get notified), and this is such a unique modification for a uniquely affordable ERV that I thought it was worth pointing out.

In Green products and materials | Asked By Nick Welch | Jan 22 16
2 Answers

Gas boiler not staying working

I have an old natural gas boiler that I need to keep going for one more winter.

I have replaced the thermopile but the unit continues to shut off and the pilot is out after a a couple of hours. I had the unit cleaned and inspected but I have doubts about the technician. While vacuuming the dust with a small handheld vacuum he never put a bag on it and my basement was then covered in dust and the air quality was "Visible".

What do I have to do to keep it running? What pressure should the pipes be at-it seems to like to settle at 12psi even if i jack it up.

In Mechanicals | Asked By Hal Sartelle | Jan 22 16
1 Answer

Insulation: what's best?

Continuous Insulation.

So who knew continuous insulation was best along with airtightness for the last 40 years?

Bruce Brownell.

What's the best strategy today to insulate?

Read up on his strategy insulating on the exterior of the entire shell. Learn how to improve upon his ideas here, on the Web, and at Building Science.

Uninterrupted insulation beats the pants off in-stud insulation. Dana here at GBA mentions this all the time, and so does the site and their contributor that holds a PHD in related science.

In Energy efficiency and durability | Asked By AJ Builder | Jan 22 16
6 Answers

Mini-split primer - how best to operate

I just got a Mitsubishi MSZ/MUZ GE 15 unit installed. My house is in Seattle, 1-floor (rambler) 1500 SF with all doors kept open. I want to get smart on how best to operate the unit for efficiency and comfort. Normally keep house at 70 degrees in day and I understand that you don't want to set back the mini-split at night. Do I just leave it at 70 degrees?

The unit seems to be working well...I used a recent discussion on these boards to locate the unit 1 foot below the ceiling (thanks Dana Dorsett) and it looks to be working continuously and not cycling.

In Mechanicals | Asked By S K | Jan 22 16
10 Answers

What's the most efficient way to build an R-52 wall in Climate Zone 5?

Looking to build a passive-inspired net-zero home, 2,264 square feet, two stories.

What's the most cost-effective or beneficial way to get that higher R-value? Double stud - blow in, 2x8 fiberglass batt with 2-2" polyiso, ICF, etc.?

Also, what are the risks with WRB (roll on) on sheathing, 1/2" plywood, 2' on center framing? Is there a concern for movement, cracks, or air leaks, as there will be no poly on the inside?


In Energy efficiency and durability | Asked By Kris Currie | Jan 19 16
2 Answers

For a straw bale infill wall, is a box beam required if the wall extends more than 12 ft. in hight.

We are planning a post and beam straw bale home with a shed style roof. the length of the house is 53 ft. and the width is 33 ft. The roof will rise along the length of the building, starting at 13 ft. from grade and rising to 21 ft. from grade. So, The wall infill will be approx. 20 feet high at its max. height and we are planning to put a box beam at the 10 ft. height. This seems like a sound decision, yet if it is not necessary, then we may eliminate the box beam.

In Green building techniques | Asked By Gerardo Larsen | Jan 22 16
8 Answers

Window data interpretation

I am hoping for some help interpreting window test data. I am looking at the two UPVC lines from Intus: Eforte and Arcade. I was sold on the Eforte line, which is clearly marketed as the better of the two options and is accordingly ~20% more expensive. When the price of Intus doors stretched my budget, I took a closer look at the ratings. What I found has thrown me off. With Intus' mixture of AAMA and ASTM ratings and the breakout of various window types in the Eforte line, I am not entirely sure I'm comparing apples to apples and I'm hoping someone can set me straight.

In Energy efficiency and durability | Asked By Jim Tyler | Jan 21 16
2 Answers

Antifreeze-Why is RV Antifreeze not ok for Hydronic Heating?

Antifreeze-Why is RV Antifreeze not ok for Hydronic Heating? My hardware store says I can use the cheaper RV antifreeze to keep my baseboard pipes from freezing if my boiler fails. However, the manufacturer on the gallon bottle says NO. Whats the difference?

In Mechanicals | Asked By Hal Sartelle | Jan 22 16
12 Answers

We want to install 2" recessed junction boxes in our unvented roof but will this lead to rotting of roof sheathing?

Martin Holladay in his 9-12-14 Musings of and Energy Nerd on How to build an Insulated Cathedral Ceiling said NEVER install recessed cans as they add heat and moisture to the roof cavity and can lead to roof failure.

We are building a flat-truss roof system with 9.5" of open-cell foam between the drywall ceiling and the roof sheathing, covered by a tapered rigid foam of 4" at center of the roof to 2" at the edges, covered by 1/2" ply and the roofing membrane. We are zone 5 climate in the Northeast.

In Energy efficiency and durability | Asked By Steve Rooney | Jan 1 16
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