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3 Answers

Venting for multiple appliances

Hey GBA,

I wanted to reach out to the community for a thought experiment.

The home I am building will have the following :

High efficiency Gas furnace
High efficiency Gas water heater
Central vacuum

All of these require exterior intakes and exhausts.

The house is a row house, so the majority of the side walls are attached to another house. Thus, this only leaves one spot where I can place the multitude of vent pipes. (which is pretty much a small alcove at the rear between the two houses) see attached image.

Asked By Jamie B | Jul 21 17
6 Answers

Insulating floor before subfloor goes in.

I need to insulate the floor of Dear Old Mom's house in zone 4c to r-38 to earn enough green "credits." Conditioned crawl is not an option because of our hot radon potential. 22" crawl space makes working down there very difficult.
Would this work:
Cut 3" poly iso (R-19.6) to fit between the webs of the 9 ½" TJIs (19.2 o.c.) and rest them on the bottom flanges before the subfloor is installed (or stage the cut pieces in the crawl before the subfloor goes in). Later, cut access holes and blow cellulose to fill the remainder of joist bay.

Asked By Mark Walker | Jul 21 17
6 Answers

Insulating balloon walls

High I am renovating a 1927 Dutch colonial with balloon wall construction. Th attic is finished but will be taken down to exposed walls and rafters. The exterior will be resided on the second level with Hardy board fibercement clapboards. The ground level is one layer of brick over wood sheathing. The roof will be replaced with an imitation slate product (DaVinci roof scrapes). All the windows were already replaced (Trim line) Aluminum clad wood thermopane windows. My question is about insulation. I will be cutting a ridge vent.

Asked By eh413 | Jul 20 17
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.

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?



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.

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!

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.

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


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.

Asked By Aron Robinson | Jul 14 17
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