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4 Answers

Is there an equation that will tell me how relative humidity varies with temperature?

I live north of Seattle and the winter humidity in my partially earth berm home runs 70%. The outside air temp tonight is 45 degrees and 95% humidity. I am trying to decide between ventilation and a dehumidifier. I would like to know at what RH that outside air will have after I warm it up.

In General questions | Asked By Mike Roberts | Nov 9 14
1 Answer

I have a Carrier high-efficiency propane furnace in suburban DC. Is 50 degrees too low to set the thermostat during the day?

During the winter while at home we like it at 70 or 68 if we are dressed warm. No one is at home at least 8 hours during the week and sometimes all weekend.

In Energy efficiency and durability | Asked By Tom Earnest | Nov 10 14
1 Answer

Can I add Roxul RockFill behind finished wall?


I have a finished condo with columns around the perimeter surrounded by drywall. Those columns are currently filled with a small amount of pink insulation. I can detect air currents coming out of some of the outlets on the columns. I was wondering if tightly packing Roxul Rockfill (http://diywithroxul.com/en-us/rockfill.html) along the base of these columns behind the drywall via the electrical outlets would negatively affect anything, given that I'd only be putting the insulation at the base and it would be mixed with the existing pink insulation.


In Energy efficiency and durability | Asked By Green Scape | Nov 9 14
3 Answers

Weathertightness of solar mounting hardware roof penetrations

Hi there,

I am in the process of reaching an agreement to have my leased PV array on my roof deinstalled, and I have a question for the professionals re my roof.

In short, while I'm not going to get into a number of the details or legal stuff here, I'll stick with the most basic facts: I've had a brand new second story since 2008, which was insulated and airsealed by a county-approved weatherization crew in that year—big checklist, blower door test, lots of sealing and cellulose and attic boxes and all the rest. It met/exceeded targets and it performed very well.

In General questions | Asked By Minneapolis Disaster, 6B | Nov 8 14
8 Answers

Planning for solar

The house I'm building will have a pretty good roof for solar. It's a simple 8/12 gable, with the south side facing a little east of south. The only real shading will be birds and clouds.

I'd like to install a metal roof, for a variety of reasons. Any suggestions for making sure the roof will work well with solar? Extra fasteners? Heavier gauge?

I'm leaning towards standing seam, but they aren't cheap, especially the galvalume variety. I'm open to other types of metal roofs.

In General questions | Asked By Graham Fisher | Nov 3 14
4 Answers

Duct heater required with an HRV in a cold climate??

I'm in the beginning stages of building a super-insulated house near Ottawa, Canada. The foundation is completed and we're about to start framing. One of the last details / sub-contractsI need to tie up is the HRV system. One of the firms providing a quote insists a 1500-2000w duct heater is required.

I recognize that the fresh air is likely to be somewhat cooler than the temperature of the house. However, this suggestions a little over-the-top given that the house will have R50 walls, R80 attic, tripled-glazed fibreglass windows and will be tight at less than 1.0 ACH50.

In Mechanicals | Asked By John Scime | Jan 16 12
10 Answers

Powered direct-vent gas water heater recommendations?

My water heater is on the last legs (just started to leak). The current unit is an atmospheric vented unit that is located in the basement. Based on Martin's article (www.finehomebuilding.com/design/articles/the-water-heater-payoff.aspx) it appears that a power direct vent (sealed) or gas condensing is the best way to go for a basement location. Besides minimizing drafting and makeup air issues, I like that I can eliminate the vent to the roof.

In Mechanicals | Asked By Brad Stoppenhagen | Nov 4 14
3 Answers

Air sealing windows

I am building a Passive House with double stud walls and all OSB seams sealed with Prosoco Joint and Seam filler. I have plywood window bucks and triple pane windows with nailing flanges installed on the exterior of the rough opening. I need to air seal the inside of the window frame to the plywood window bucks. I would like to fill the space between the window frame and the plywood with foam and then air seal.

In PassivHaus | Asked By Gerald Blycker | Nov 6 14
6 Answers

Efflorescence / spalling in brick basement


I think I have an efflorescence/spalling problem in my basement foundation walls. This will be a bit of a long post as I want to include any details that may be relevant.

I'm not sure of a few things about it:
A) How much of a problem it is (cosmetic or structural?)
B) If the paint on the basement walls is a contributor
C) What the source of the moisture is (although I have suspicions)

Photos posted here: http://imgur.com/a/7TtkL

A bit of background:

In General questions | Asked By Jon Haque | Nov 6 14
4 Answers

Where does the water vapor go?

This is a question more of curiosity and needing an education rather than a specific request for advice or guidance on a building issue.

In General questions | Asked By Ted In New Hampshire | Nov 4 14
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