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5 Answers

Unvented cathedral ceiling — insulating from above

I am re-doing my family room roof, which is a cathedral ceiling.

Since the roof is being re-shingled, I thought it a good time to remove the sheathing and lay down some closed cell foam. I have some unopened from a previous project

Everything I've read about unvented Cathedral ceilings talk about them drying from the inside. Obviously this can't happen if I'm spray in the closed cell foam onto the dry wall ceiling from above

The ceiling is 8" from drywall to plywood

In General questions | Asked By Paul Buchkowski | Jun 25 16
9 Answers

How efficient are recirculating kitchen range hoods with carbon filters at removing air pollutants from cooking?

I looked at a few of these filters for the recirculating range hoods and they didn't look all that impressive, but maybe I am looking at the wrong hoods. If passive houses are using recirculating hoods how well are the hoods actually working. Clearly there is a tradeoff for energy efficiency and range hood function. Is there any specific data on this? Are there certain types of carbon filters that work better than others? I am not talking about removing moisture or CO from gas ranges but more grease and other pollutants produced when cooking with electric ranges and ovens.

In Mechanicals | Asked By Dillon Vautrin | Dec 16 15
1 Answer

Vapor barrier

Am looking into building ICF homes in another country. My question is they do not generally heat and air condition their homes due to high energy cost. It is warm and humid and am not sure what, if any vapor barrier should be used in the roof area.

In Energy efficiency and durability | Asked By Thomas Webster | Jun 29 16
32 Answers

Direct vent vs. power vent gas water heaters

A recent blower door test/audit has alerted me to the fact that my natural draft hot water heater can backdraft in worse case scenarios (range hood/clothes dryer/bath fan on). It seems to reverse back to a correct draft after a few minutes. It's only about 6 yrs old, so I hate to replace it, but not as much as I hate the idea of the back draft.

In Mechanicals | Asked By Erik Addy | Mar 8 16
13 Answers

Does anyone have experience with Zehnder ComfoFlex?

We are building a new house and in the final stages of design. The design includes an HRV and Zehnder ComfoTube looked great until I discovered that it is not UL listed. So, I'm curious if anyone can provide feedback on ComfoFlex. There isn't much on the intertubes...

In Mechanicals | Asked By Trevor Fontaine | Feb 9 16
17 Answers

R-values of ceiling and walls

Zone 5a (on the border of zone 4)
Existing uninsulated concrete slab.
No basement. 2x4 frame.
A bunch of newbie questions.

http://www.homepower.com/insulation-zones
Why is the insulation recommendation for an attic so much higher than for an cathedral ceiling?
Both are the shell of the building but the attic has an ceiling under it that at least adds some insulation value. I would expect the recommendations to be closer or even reversed.

Many sites stress the importance of a high R-value to save energy.

In General questions | Asked By Tony Tibbar | Jun 3 16
8 Answers

Is a dehumidifier needed in a tight house?

I've read several times that it's common for tight, well-insulated homes to need supplemental dehumidification, as the AC doesn't run enough to dehumidify the home.
As a person who is especially sensitive to humidity, I'm very interested in this.
I wonder if an equal level of comfort can be achieved more economically with a higher temp. set point but lower humidity. (In my case, Chicago area- warm and humid in the summer).

In Mechanicals | Asked By Ben Rush | Jun 27 16
2 Answers

Best practice for extending out a wall

Hi GBA,

I have a 2nd floor gable end wall which is constructed of (from outside) brick, air gap, block, air gap, 3/4" plaster/blueboard. There is no framing/insulation in the wall. We are converting an existing closet to an opening and to part of the above wall will be furred out with 2x4's. I would like to insulate it while we are in there but as always don't want to create issues.

In General questions | Asked By G S | Jun 29 16
7 Answers

Would IGU windows using laminated glass be the preferred choice to eliminate UV?

I am considering the use of an Insulating Glass unit (IGU) using laminated glass. I assume the laminated glass will be on the interior side. I live in Seattle so air conditioning is needed only 3 months/year. I want low U-factor and high light transmittance (70% is ideal). Also want to kill UV as much as possible. Laminated glass will kill 99% of the UV while some LoE coatings can give 95% but reduces the transmittance to 66%.

Here is a possible configuration using Cardinal Glass:
a) Outboad lite is 3mm glass with LoE270 on surface #2 (and perhaps LoE-x89 on surface #1)

In Energy efficiency and durability | Asked By Mike Chapman | Jun 28 16
17 Answers

Zone 1 home addition — Dual-zone HVAC strategy?

I'm building a 1,700 sq. foot single story addition to my home in Houston, TX. 1,000 sq foot are a woodworking shop, 700 sq feet are living space. Living space is multi-room, think small apartment (kitchen/den, bedroom, bathroom, closet). Shop is one big room with a separate mechanical room. My current HVAC system won't handle the 700 sq feet of living space, which is also on the opposite side of the shop (maybe 100' from the current hot-attic system).

Current house is traditional stick frame, brick veneer with batt insulation and blown-in in attic. Gas available for heat.

In Mechanicals | Asked By Mark McFarlane | Jun 27 16
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