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6 Answers

BEopt results

Tried using BEopt for my house and the results were a shock, somewhat. I live in Zone 4 in Maryland and was concentrating on the things I know will be occurring in the near future, attic insulation and wall retrofit insulation.

According to BEopt, the biggest insulation bang for the buck was the wall insulation. Putting in R13 of cellulose with Grade 3 installation produced a drop of about 500 therms per year. (I assumed Grade 3 installation was appropriate, since 1) it will be a retrofit and 2) I have a severe lack of faith in contractors.)

Asked By Jeff Towson | Jan 22 18
17 Answers

Header hangers vs. jack studs: Thermal bridging?

Advanced framing articles all seem to advise the use of header hangers instead of using jack studs. The idea is, less wood and more insulation in the wall, and better the thermal performance.

Has anyone studies whether the thermal bridge of a jack stud is better or worse than a header hanger? A jack stud is very large by comparison, but a header hanger is a relatively heavy gauge piece of steel that bridges right from sheething to drywall.

Beyond the thermal bridge, could a cold spot behind the drywall cause moisture issues or condensation on the interior surface of the wall?

Asked By Lance Peters | Jan 21 18
9 Answers

New house CZ3, ducted HVAC & air handling design questions

2500sf single story 3 bedroom north bay, California house with conditioned rat slab crawlspace. 3 bathrooms, family rooms with a gas fireplace, "great room" kitchen/DR/LR is 30x42.

Plans call for 2x6 walls with 1" of well sealed foam (exact type still tbd), 500sf of casement windows and french doors with sub-.30 ufactor glazing, unvented 6/12 exterior pitch scissor trusses.

Asked By Rob Hunter | Jan 21 18
1 Answer

Insulating an unvented roof with foam boards on the interior


I am hoping for advice on my historic home. The house is a 150 year old italianate home in climate zone 6a, with a low-hipped roof and no true top "ridge." The roof assembly is unvented, and accessible from the unfinished 3rd floor space, which is a large, open 40x40 ft. room, The rafters are full dimension 2x8 boards.

Asked By brpbrown21 | Jan 22 18
2 Answers

Rim joist external insulation and air barrier: How to?


I plan to recess my rim joist so that 2" EPS can be added as a thermal break. This will be flush with the studs so my sheathing can cover the whole area. Pretty standard.

I want to bring my vapor retarder (Intello or Membrain) out and around the rim joist so it attaches with the vapor retarder on the inside walls. This should result in a seamless air seal from foundation to trusses. Again, pretty standard.

My first question is, does the 2" EPS go on the inside or outside of the vapor retarder and why?

Asked By Lance Peters | Jan 21 18
14 Answers

What materials meet code for "flash and batt" on my ceiling?

I have an unfinished basement and I am looking to add about 5" of insulation to fill up the joist bays on the ceiling. The bays are 7 inches deep and will soon have around 2" of foam.

I am wondering if I would be able to fill the bays with Roxul and cover the entire ceiling with house wrap.

The reason for the roxul is that if necessary it would still be possible to access what's in my ceiling (wiring and some pipes), without the negative effects on air quality of the fiberglass.

I understand I can trim the roxul with a knife to match my very uneven 80 year old ceiling joist bays.

Asked By Robert Wan | Jan 12 18
1 Answer

Are unfaced fiberglass insulation and rigid insulation board a good choice to insulate floor joists?

I live in Memphis, TN. Original part of house is 70 years old (1100sf). The addition in rear of original house is 45 years old (1000sf). No insulation in crawlspace of either section. Floors are cold, mostly in addition, and uninsulated. Crawl space is vented. At best there is 32" of head space and at worst 18" in addition. Limited to "belly space" in original section. No outside gutters yet.

Asked By tc3fngrs | Jan 22 18
5 Answers

Insulation upgrades

Hi Everyone.

Thank you in advance for your feedback, you have all been so helpful.

Zone 5A (coastal Mass) house.

I have an older 3200 sq ft home with a mix of well-pointed fieldstone foundation and poured concrete. The 1000 sq ft attic is currently air-sealed in most places, and has a mix of fiberglass batts and cellulose for about R-30. I have 10 recessed lights in attic, which have the LED airtight retrofits with gaskets, but are not covered in cellulose. The recessed fixtures are IC-rated. The remainder of the home has vented cathedral ceilings (sigh).

Asked By Justin Brown | Jan 22 18
14 Answers

Heat loss, can lights in cathedral ceiling

The information about replacing or retrofitting can lights with LED fixtures has been really helpful. However, I have a cathedral ceiling with what I think are standard can lights, with a diameter of 7.5" within the can, and about 9.5 " total diameter including trim--the ceilings are about 18' high so I am having a difficult time getting to one to carefully measure.

I cannot find anywhere residential can light LED retrofits for this size. I've looked at what Cree offers, as well as Home Depot and Lowes, and they all max out at 6".

Asked By JWBDSR | Oct 17 17
18 Answers

Cycling of heat pump

I have a Fujitsu heat pump with two indoor units each in relatively small rooms. (For good or bad, this decision was made because I was not satisfied if only one room had a unit that sufficient heat could be transmitted to the second room and I wanted each room to have its own thermostat. I recognize that they are larger than I need but I did not see good alternatives) Currently both units are set on "minimum heat" (50 degrees F) because the rooms are not occupied for days at a time.

Asked By David Martin | Jan 14 18
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