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6 Answers

EPS under siding

Hi all, I have a weekend cottage on a lake here in middle GA that was built in the mid-80’s that is in need of some serious TLC. One of the projects I’m planning on doing is to re-side the house with Hardiplank lap siding. The current siding is cedar lap on top of 1” foil faced Expanded Polystyrene (EPS). The corners are set with ½” plywood and ½” GP particle board for shear strength. Currently, there is no felt or house wrap between the sheathing and cedar siding. Due to 10 years of lack of maintenance and woodpeckers; the current cedar siding is in really bad shape.

In Energy efficiency and durability | Asked By Rudi Schmoll | Jul 21 17
6 Answers

Will R-70 cellulose sag ceiling drywall 24" o.c.?

My plans call for an R-70 ceiling of loose-pack cellulose in double-netted bays between trusses 24" o.c., with 5/8" Type X drywall holding it up as my air barrier. My installer says this will weigh about 2.55 lbs/sq/ft. Is this too much? Will it sag over time or pop screws? Do I need to use some special (expensive) low-sag drywall? I don't want to go to the expense and lost clearance of, e.g., an OSB layer above the drywall.

Anyone have experience with this?



In GBA Pro help | Asked By Randy Jorgen | Jul 16 17
1 Answer

Sand is becoming a scarce resource

Good Day,

There are a number of recent stories about the growing scarcity of sand and how this can impact construction, industrial and electronics industries (for example, see http://pulitzercenter.org/projects/deadly-global-war-sand). One example cited how China has used more sand for construction projects in the last few years than the US used on all of the 20th century.

In Green building techniques | Asked By Douglas Epperly | Jul 21 17
2 Answers

Build my own SIPs, or just frame it?

I am in the planning phase of building a second home and a shop on my property. I have access to as much insulation material as I need in 22" wide and various length (from 36" to 64") rigid foam insulation (door cut outs with the skins still on r 6.25 and 1 3/4" thick) for free!

In Green building techniques | Asked By Mathew Bean | Jul 20 17
4 Answers

Cost-effective option for improving cathedral roof insulation?

Hello all, Hello Martin.

I've read a number of GBA articles and posts regarding how to insulate cathedral ceilings, but I'm hoping for suggestions on the best way to improve our specific existing condition.

I'm in coastal Maine, zone 6a. Windy spot near a coastal river, not much shelter.

The 25 x 25 main wing of my 14 year-old house has a scissor-truss roof, with basic asphalt shingles in relatively good repair.

In Energy efficiency and durability | Asked By User-6889078 | Jul 21 17
2 Answers

Manual J load done — trying to determine kWh for ductless heat pump

Here are my numbers for 700 square foot guest home, zone 4b
Heat Load 9,725 btus/hour
Cooling Load 7,503 btus/hour

I know there are several variables but the unit I am looking at is a Ceiling cassette rated at 20.2 seer 12k btu unit

My question is there anything that has been published that could give me a good estimate of what my kWh could be.

Or some numbers at different temperature conditions


In Energy efficiency and durability | Asked By Richard Riso | Jul 20 17
11 Answers


Greetings all. We built our house 5 years ago with much good guidance from this site. We installed a wall assembly with 1/2 inch osb, then a layer of housewrap, then a layer of 1/2 inch foam board with the seams sealed and flashed to outtie type windows. We installed Certainteed cement board siding. This siding had manufacturing issues and was subject to a class action settlement because it would crack, etc. We have several cracks, etc. We have filed for the claim and are preparing to replace our siding with James Hardy. Wish we had gone with that brand in the first place.

In General questions | Asked By Aron Robinson | Jul 14 17
1 Answer

Yep! Cathedral ceiling: To vent or not?

Okay, so I have tried to do all my homework before asking the question but I seem to be confusing myself more with every article and question I read including Martin's "All About Attic Venting" article. Simple 4/12 cathedral roof with no intrusions (hips or the like) on a new construction home. Climate Zone 6 with high snow load potential but infrequent. Originally I was going to do a metal roof but value engineering is pushing me to shingles and my dilemma. The rafters are 2x14 TJIs so I have some room but I am aiming for upwards of R-60. Here are the two scenarios I am contemplating.

In Energy efficiency and durability | Asked By Bevan Arch | Jul 20 17
3 Answers

Can I use two layers of Tyvek in a wall assembly without moisture problems?

I am building a house which has a REMOTE wall system in it (foam "outsulation"). Although I passed on the relevant information to the builder, who is usually on top of the details, he managed to mess up with the window bucks.

The wall structure is 2x4 studs (with R13 cavity insulation), plywood sheathing, Tyvek Drain Wrap (wrinkled stuff) 2 layers of EPS foam of R10 each sealed with Siga Wigluv tape, then 3/4" plywood furring strips followed by wood siding.

In Green building techniques | Asked By Gary Dick | Jan 11 15
3 Answers

Fastening plywood gussets

Hi, I will be fastening plywood gussets to my 2 by 6 rafters to deepen the bays for additional insulation in my attic. The plywood is 3/4 inch thick. Gussets will be 11 inches long, mounted onto 4.5 inches of the long side of the rafter and allowing me to deepen the rafter by a further 6.5 inches. I have 3 questions.

1. How to fasten the gussets? Naively was thinking of 2 inch long screws. Then I read screws are more likely to break than nails. Should I use 5d or 6d box nails? Use maybe 3 nails per connection with rafter?

In General questions | Asked By matthias paustian | Jul 20 17
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