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4 Answers

What's the best way to address insufficient foam R-value outside the vapor barrier in Zone 5?

We're in new construction now, and had to put the brakes on due to moisture in the wall assembly. Our wall design meets code for Zone 5 (Illinois), but we want to make sure we never have a problem with mold.

We're using Ox Engineered Products Structural Insulated Sheathing (SIS) 1" polyiso R-5.5 and 2 x 4 stud cavities filled with un-faced mineral wool, Roxul R-15. The Ox SIS (formerly Dow) has a perm rating of 0.3, so its use requires drying to the interior. It is meticulously taped and sealed, so it is also our air barrier. The Roxul is very vapor-open (roughly 30 perms).

In Green building techniques | Asked By Dave Brooks | Feb 25 15
9 Answers

Signs of a properly sized furnace?

The most common theme I see when people talk about oversized furnaces is reduced runtime & short-cycling.

But what does short-cycling mean quantitatively?

a) 5 mins on, 5 mins off, repeat
b) 5 mins on, 10 mins off, repeat
c) 10 mins on, 5 mins off, repeat

According to the Manual J heat load, my furnace is only 5% oversized. When I set the stat to warm up more than a couple degrees, it does take a while (e.g., more than an hour). I've measured almost 100 degrees from my warmest supply register & 68 degrees at that room's return (rise of 32deg).

In General questions | Asked By Jeff Watson | Feb 26 15
4 Answers

EPS, PolyIso, or Double Stud Wall

I'm doing my research and having quite the controversy between these three options.
Zone 5B - SO I have to worry about hot summers and freezing winters.

In a couple of questions I posted here I learned that EPS is more of the favored child around here while XPS is considered more costly (Agreed) and poorer performance in cool temperatures (I don't know, just going by what I heard)

In Green building techniques | Asked By Nicholas C | Feb 26 15
4 Answers

What happens to inward drying assemblies after a dozen coats of paint?

I'm just curious what happens to the assemblies after a house has been lived in, repainted, sold repainted, turned into a rental (lots of re painting), etc. you get the idea. I've only read about permeability after a few coats of paint and want to know expert opinion about if this can lead to future disaster.

Also, has anyone measured the permeability of GWB with a covering primer like Kilz that is shellac based?

Finally, how does the permeability of thin veneer plaster compare to level four drywall or skip troweled drywall mud?

In Energy efficiency and durability | Asked By Rick Van Handel | Feb 25 15
7 Answers

Any good entry doors out there yet?


We're almost done with our Minneapolis energy retrofit, but I still haven't come up with any good entry and side door options. The home is framed with 2x4" walls, and there is also limited side to side clearance to add a more substantial European frame.

In Green products and materials | Asked By Ryan Griffin | Feb 25 15
3 Answers

Is everyone on vacation?

Seems like since the reboot of the website the amount of new content has gone way down.

Lots of "best of fine home building"= Boring=Why pay expensive website fee

In General questions | Asked By kye ford | Feb 25 15
1 Answer

Exterior rigid foam question

I live in the San Francisco Bay Area and am applying exterior rigid foam as follows:

plywood-2 layers of 3/4" foil faced polyiso - WRB -rainscreen - fiber cement lap siding

In many of the articles I have read on the subject, it recommends applying an adhesive on the foam on the panel edges were it meets the bottom of the wall and the perimeter wall edges.

In Green building techniques | Asked By Randy Mason | Feb 25 15
6 Answers

Air-source heat pump vs. AC/furnace

I am contemplating some different HVAC options in Connecticut (zone 5). I currently have an 80% efficiency Carrier Infinity NG furnace (8 years old) that can be paired with a Carrier Greenspeed heat pump. I can do that for $11,400 before incentives, or replace my existing and dying 10 SEER AC unit with a new 16 SEER for $8,000.

In Mechanicals | Asked By Anthony Kane | Feb 24 15
6 Answers

Insulating and air sealing kneewalls


I recently bought a house, and over the last few months have figured a number of issues with the insulation in the knee walls. A few notes about the house:
*In MN (Climate Zone 6, almost 7).
* ~20 years old
*Built with a poly vapor barrier on the inside behind the drywall
*2x6 framing, currently no sheathing on the attic side, R-19 fiberglass is currently in the kneewalls
*Only way into attic is through a 24x30 opening
*Due to the architecture of the house, I have many knee walls, ranging from 7.5', 4', and two that progressively get shorter as you go down a scissor truss.

In Energy efficiency and durability | Asked By Ross A | Feb 22 15
10 Answers

Questions on a "not-so-deep" retrofit...

1948 mid century/ranch, stucco exterior
Wood shaving insulation with paper face stapled to framing
2 layers of (I believe) "plasterboard" 3/8" over 5/8" = 1" total
Kitchen renovation found no evidence of moisture in the ceiling or walls, removed wood shaving insulation and replaced with R-19 batt (regrettably but can't undo now)
Polyethylene vapor barrier on interior side of renovated walls (insulation code official laughed when I said that I expected him to closely scrutinize the vapor barrier and he said, "There are so many holes in this old house [windows and doors], this r

In Energy efficiency and durability | Asked By Justin Merkovich | Feb 20 15
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