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5 Answers

Air sealing the cap of a double stud wall

I am currently building a double stud home in NH and am in the process of air sealing all exterior cracks with siga tapes. Since my builder decided to build the interior portion of the double wall after the exterior, we were left with a 4 inch gap between the two walls at the cap. We will be filling the 12 inch cavity with dense pack cellulose, so this gap at the ceiling needs to be blocked off. We decided to fill the gap with strips of plywood which has resulted in cracks on either side of the plywood filler that I'm worried may leak air.

In Green building techniques | Asked By Chris Roche | Dec 13 17
1 Answer

Window NFRC ratings and airtightness

I've read about NFRC rating. Intuitively, infiltration seems like it should be one of the more important considerations- if the window is leaking air, the U/R value seems secondary.

I'm looking at windows that are NFRC listed. However the NFRC listings on the website do not seem to include infiltration for many windows. You can navigate to the particular window via manufacturer and window type, and from there select the product line, which then brings you to a page with "General Information: and a ratings table.

In Energy efficiency and durability | Asked By C L | Dec 14 17
3 Answers

Best strategy to rehang the ceiling drywall?

Our basement (ground level) room suffers tremendously from the noise in the upper level where the kitchen and dining table are. Walking and moving chairs noise is very pronounced downstairs. I'd like to improve on it. We should have used resilient channel before hanging that ceiling drywall, but we did not. There are also 16'' tall floor joists - maybe the cavity even amplifies the noise? First floor is just the hardwood floor with a minimal (very thin) cork layer below it.

In General questions | Asked By Lucyna de Barbaro | Dec 13 17
4 Answers

Ductless minisplit heat pump in a poorly insulated home?

Good morning,

I’m trying to find some information on the pros and cons of Ductless mini split heat pumps. (Mostly if one could work in my situation.)

My home is a 1930’s Cape Cod style home (Climate zone 4) with a full shed dormer on the front. The home is roughly 1100 sq feet. The first floor approx. 780 sq feet has an open floorplan that connects living/dining and kitchen with a sectioned off bathroom and guest bedroom. The 2nd floor approx. 275 sq feet serves as a master suite that has a sectioned off bedroom and bath.

In General questions | Asked By Andy Pappas | Dec 13 17
1 Answer

Horizontal ducted minisplit ducting

I plan on using a Mitsubishi 12K BTU horizontal ducted mini split, Model: SEZ-KD12NA4R1.TH to provide both heat and AC to two second floor bedrooms. The unit would be inside the building envelope in a dropped ceiling in a hallway between the bedrooms. I'm having trouble determining what adequate ducting would be.

The Mitsubishi submittal document has graphs for different static pressure that relate to CFM but I struggle to relate this to a duct design.

In Mechanicals | Asked By Jim Sweazey | Dec 12 17
3 Answers

Exterior mineral wool insulation: Batts vs. denser boards

I am planning to add exterior mineral wool insulation over the exterior of my double wythe brick walls. The typical choice is high density boards such Roxul comfortbatt 80. They are substantially more expensive than the medium density mineral wool batts that typically go into stud bays on the interior such as Roxul Comfortbatt. I think the price difference is factor 3 at least on a $ per R per sqf basis. Hence my idea: Attach a 2 by 4 on the flat with Tapcons to the brick.

In General questions | Asked By Matthias Paustian | Dec 12 17
4 Answers

Choose between window condensation or gaps in hardwood planks?

I built a new home in 2017. This is our first winter living in the home, and I'm running into a humidity problem.


In Mechanicals | Asked By Ryan Lazuka | Dec 11 17
9 Answers

Indoor Humidity - dew point & monitoring condensation

I live in Colorado, Zone 5, where our winters frequently drop down to 0-20F and outdoor humidity levels might be in the teens.

I recently figured out my chronic congestion gets about a hundred times better at 45% humidity. Despite all the sealing & insulating we've done, the plants and three dogs, our house drops down into the twenties in winter, sometimes even the teens. Because this is a retrofit, I probably can't hit 0.6ACH. I'm around 1.5ACH right now, and the next sealing & insulating step will require ripping off the roof, so that's on the back burner.

In Mechanicals | Asked By pshyvers | Dec 11 17
6 Answers

Insulate "crawlspace"

I put crawlspace in quotes because this is more of an unfinished basement with dirt floor. The joists above range from 7-10' above grade. The floor slopes 5' in the middle. I currently have no plans to finish the basement.

The house is in Zone 6. I want to make it more cost effective for heating and keep the moisture controlled.

My plan is as follows:
1. put 15-20 mil plastic over the current plastic sheets which has been walked on and is now covered in holes. Re-attach to foundation and seal using tape.

In General questions | Asked By James Bodell | Dec 11 17
6 Answers

Exterior foam with stone and 10 mm rainscreen

I am planning to build a new house and I have a couple of questions.

The house will be in climate zone 2 - hot-humid (near Houston, TX). The walls will be 2x6 with 3.5" of open cell spray foam. The walls will be sheathed with OSB and we are planning to add 0.75" of foam board (R4) on the exterior and use Tyvek drainwrap and a 10 mm rainscreen (i.e. MTI Surecavity).

Some of the walls will have a full stone veneer (3"-5" bed). Some will be half stone and half Hardie and some will be all Hardie. My questions are:

In General questions | Asked By E247 | Dec 5 17
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