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6 Answers

Can rigid insulation be safely used in the center of a double stud wall?

Joe Lstiburek's details for double stud walls show a layer of OSB/plywood in the center of the wall for an air and vapor barrier. Could a wall be assembled with R-13 batts in 2x4 framed walls, separated by a layer of 2"-3" rigid insulation? It seems like the first condensing surfaces of the rigid insulation would safely remain below the dewpoint, and foil faced insulation like polyiso would be a very effective air and vapor barrier. This would be built in climate zone 4.

Asked By Jason Whitacre | Nov 30 16
4 Answers

Insulating a wall that is half plaster/half drywall?

We live in a home that was built around 1920 near Chicago, IL. Our plot is narrow and the front portion of the home is the original house, with a very large addition on the back from the previous owners (2007). The staircase in the old house was sloping heavily to the right. We had a structural engineer come take a look and he attributed it to natural settling and didn't see any signs of continuing movement and didn't make any recommendations aside from sistering one joist. I'm not a master carpenter, but I have built a staircase or two in my life.

Asked By Al Ciu | Dec 2 16
15 Answers

Another crawl space in the Northwest

Hello all, I have a 1150 sq ft rambler house in Fall City, Washington (near Seattle), zone marine 4c. I am currently in the process of redoing the crawl space. I have pulled the damaged and rodent infested insulation down, and removed the town vapor barrier. It seems I had some rodents that were digging past the foundation and getting into the crawlspace, ruining everything.

Asked By David Meyer | Nov 28 16
1 Answer

HVAC Multifloor return system - Should I get grills with dampers to control velocity?

I am designing the new HVAC system for my home. I plan to do a 4 zone system, lennox SLP98UH090XV60C

Attached is a diagram for a visual.

I am getting into the return ductwork. To my understanding it's good practice is to have a return grill on each floor and it will better circulate air. Also, I separated them into two zones to help with noise transfer between floors.

Asked By Jamie B | Dec 2 16
1 Answer

How important is a thermal break between a house foundation and an attached garage foundation?

Our footings were poured today for a new house and attached garage. The walls of the basement foundation (9') and garage foundation are scheduled to be poured next week.

Looking over the plans, our concrete sub is worried about the 7" thermal break between the basement and garage foundations (no physical connection) as currently drawn on the plans. The separation is there in order to allow us to attach 5" of Roxul Comfortboard 80 to the basement foundation (we'll be doing the same for the whole exterior perimeter of the basement foundation).

Asked By Eric Whetzel | Dec 2 16
7 Answers

Boards covering the top plate to air seal in attic - Top plate is not accessible

Many of my top plates are completely covered by other boards. I.e. Some of the top plates have 2 2x4 boards butted together on top of it (Effectively making a 2x8 with a split in the middle.) While this 'covers' the gaps I do not believe it creates an air seal.

Should I assume it will be sufficient to seal around and between these boards?

- It would increase the length of my sealing by ~ 50% since I would be doing two sides and a middle. (Not counting the ends which are negligible). However would be much easier than prying them up.

Asked By Charles Lee | Dec 1 16
7 Answers

How to employ a mixing valve in a closed loop radiant heat system

We are just wrapping up the new roof on my project house and now its [past] time to turn our attention to HVAC - or, more specifically this time of year, Heating! This 1975 house came with radiant heat ceilings as the only source of heat. Recently we have been having night time lows in the teens and daytime highs here in Northern Nevada zone 5 at 5000 feet are usually in the 40's. I have done some preliminary calcs on heat gain/loss, and plan on doing a full Manual J model before laying out any cash for components.

Asked By Roger Smith | Dec 1 16
4 Answers

Do they sell Dow Thermax anymore?

I have a big basement I need to insulate from the interior and I'd like to avoid the cost of framing and drywall since the basement will only be used for storage.

Do they still make Dow Thermax? I can't seem to find it anywhere. Is there a new product that meets the fire ratings as Thermax, that won't require drywall over it?

Asked By Clay Whitenack | Feb 9 16
1 Answer

Flame Spread rated spray foam?

I heard yesterday about a new spray foam product that had a flame spread rating that met code without the application of an additional coating - Apparently it is a distinctive color so building inspectors can recognize and sign-off on it.

Does any one have any info on who is producing this product and how the pricing compares to foam with flame spread resistant paint applied after installation of the foam? Does it contain halogenated flame retardants? Is information available on what the flame retardant used is (TPP? or TCPP?)

Asked By Michael Chandler, GBA Advisor | Dec 2 16
12 Answers

Turning a previously enclosed porch into a bathroom- how to insulate slab?

I am renovating an old house in Climate Zone 3. A previous owner turned an enclosed porch into a study. It has a concrete slab on grade floor, stone columns, and a low brick wall at its perimeter. The exterior finish is a layer of Celotex (I am assuming this is an insulated board) and stucco and the wall cavity as constructed is about a foot thick. It is sort of framed up as a double wall. There is an almost 5 inch step up into the adjoining room, so I have plenty of space to build that floor up with insulation. I want to finish the floor with tile.

Asked By Helen Reinecke-Wilt | Nov 30 16
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