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8 Answers

Another flat roof question

We have several hundred sq. ft. of unvented flat EPDM roof above a single story addition. The rafters are 2x8. We recently cut access and found 2-3" of very old fiberglass batts in the rafter bays - a total roof insulation of R11. When the roof needs to be replaced in >10 years, we will install external foam sheathing.

In the interim, what is the best way to increase R value without creating a moisture problem? And if every approach has risks, what are they?

Thank you.

Asked By Emerson | Feb 6 18
1 Answer

Understanding water heater specs

I have some questions about tank type water heaters:

How do you compare the sizing needed for a gas tank vs. electric heat pump type tank. I read (perhaps on this site?) that heat pump type tank water heaters have much slower recovery and thus, for the same hot water demand, a house would need a larger tank with the heat pump type.
1. Is there a chart to compare needed tank sizes between gas & heat pump type tanks, including how the recovery rates of a specific tank impact this?

Asked By C L | Feb 11 18
9 Answers

Relatively non-toxic concrete joint filler/sealing material that will last?

I have a failed cove joint in my below-grade level, and need to replace part of the fiber board joint material that exists between the slab and foundation wall. I need it to be a permanent type repair, as it will be difficult to get at the joint after my remodel, and I have radon present in my soil.

Does anyone know of a product that both works well (i.e may have a 20+ year life on concrete, remaining attached and flexible) and isn't highly toxic or classified as a carcinogen?

Asked By Rossn1 | Feb 8 18
10 Answers

House next to deep rock quarry: How can I tap water below 12-16" of ice for heat?

We have 50' deep water 50' behind our house.Water is very clean with 20' visibility at least-comes from limestone rock --no creeks or rivers--it is a hole in the water table. 8 acres. we have only 48" of earth above flat limestone shelf that is entire area around us. It was a Quarry for limestone way back. the water is at top of shelf--about 48" below the yard.

My minisplit is outside in 20 degree winter air while its 32 degree's or above a short distance away?

Asked By Scout159 | Feb 10 18
2 Answers

Too many wall insulation options?

Building a new home in Kansas City (DOE Zone 4A; mixed-humid {not too far from cold}). Summers are too hot and winters are too cold. Looking for the most cost effective and efficient method to insulate the exterior walls. Reading different books and forums, I'm having a hard time coming up with a comprehensive plan. My in initial thoughts were, starting from the inside:

2x6 studs, 24 OC. Uses less wood than 2x4 studs, 16 OC and reduces thermal bridging.

Asked By BIC2 | Feb 11 18
7 Answers

Minisplit temperature difference between floor and ceiling

We live outside Philadelphia and have had a very cold winter. We had a mini split uint installed in a newly expanded room and blocked the two forced air ducts from the old portion of the room. The floor temperature is vastly different than that coming out of the unit.
A few details. Home was built in 1954. Half of the room (old section) is over an inaccessible crawl space. I has a flat ceiling and a ceiling fan. It has one outside wall.

Asked By Bob Whitemarsh | Feb 10 18
5 Answers

Cathedral roof, unvented, rigid foam

Hey GBA,

I've been reading several articles on the merits of Vented/Unvented cathedral ceilings. I'm about to build an energy efficient home in a mountainous zone 6 with lots of potential snow load. I'm trying to get R-30 on the walls and R-60 on the roof. Our climate is quite dry and I assume most of the vapor pressure will be from inside to outside in winter.

Asked By Steve Mackay | Feb 9 18
2 Answers

Air-sealing a Solatube on new construction

I am planning a house, with cathedral ceilings, and my client needs some daylight from the east. The only way to get it is with a skylight, on the east slope of a cathedral ceiling (or a dormer, but let's not go there).

We are planning a "pretty good" house with an air barrier at the ceiling (drywall or MemBrain). It seems like a solatube (or competitor) would be better than a full skylight. But I cannot figure out how to run the air seal (and no response from solatube . . . 0.

Does anyone have experience with tying a solatube into a ceiling air barrier?

Asked By Mark Harrison | Feb 10 18
2 Answers

Do we need to overlap rock wool?

It seems like it's common practice to seams in mineral wool, as seen in this Eco Home video:


However, in looking at Rock Wool (Roxul), a claim appears on page 3 of the following pdf that the material will knit together when pressed.


So, if one using a thickness that can be accommodated by a single product, say 3" of Comfortboard, is there any benefit to going with two layers of 1.5" insulation vs a single layer of 3"?

Asked By Elfo | Feb 10 18
9 Answers

Heating fuel usage diagnostics

By instinct it seems to me like I blew through a lot of propane, so I am trying to wrap my head around the best way to gauge useage, compare useage, find out what rate of useage is good and whats terrible.

Asked By T Carlson | Feb 9 18
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