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15 Answers

Ineffectiveness of increasing R-value with more than 4 in. of closed-cell spray foam?

I have been told a number of times that using more than 4" of cc spray foam (in a wall or roof assembly) has little value at increasing r-value. In other words, does using more than 4" not have a linear increase in r-value? The reason I ask is b/c I need the recommended r-35 against the bottom of my roof sheathing (with blown-in cellulose in the remainder of my cathedral truss) to prevent the roof sheathing to dip below the dew point and create condensation. Any thoughts? Thanks.

In GBA Pro help | Asked By Matthew Michaud | Feb 2 13
4 Answers

Controllng infiltration through entry way doors

In my caulked-to-death cottage, there is annooying air infiltration around my front and back doors. The inflow increases when exhaust fans are turned on, the negative pressure results in the opening up/softening the connection and allowing air in.

I am surprised not to be able to find much info on how to seal entryway doors. I can't find any lock-sets or after-market door sealing solutions that convince me of their effectiveness.

In Energy efficiency and durability | Asked By Oak Orchard | Feb 5 13
8 Answers

I read the good article on building a vaulted ceiling — too late

I read the good article on building a vaulted ceiling. However, that is too late for me since I already have vaulted ceilings throughout my house.

In General questions | Asked By Gene Byrd | Jan 28 13
1 Answer

How to insulate the ceiling/roof?

I have a chalet-style house in Virginia which needs insulation. Built about 1970 as a Linden model, it is hard to heat in the winter. We installed a propane fireplace to help the heat pumps in the two stories plus basement. Summers are not such a problem because the surrounding trees give shade.

In General questions | Asked By robert thomas | Feb 6 13
4 Answers

Bath fans: ceiling-mount or inline?

On my new build currently under construction, I am trying to determine which route to go with the bath fans. I have a 100sqft bath and a 65 sqft bath. The 2 vent locations are either a gable end or straight up through the roof. They will go in a unconditioned vented attic space with r60 blown insulation.

I much prefer the gable, however the closest gable is about a 25' duct run for the fan. I am thinking if I go this route an inline fan may be the better solution, such as one from Fantech.

In Mechanicals | Asked By Jesse Lizer | Feb 5 13
3 Answers

Do I need an attic fan for a unused attic?

I have an attic space on top of the two car garage which is insulated. There is no ventilation. I only use this space to store empty tv boxes and computer boxes just in case i have to return. this attic opens into a closet upstairs. The highest point is 4 feet. PLease help me with this.
thank you

In Energy efficiency and durability | Asked By kamala naidu | Feb 6 13
1 Answer

Can I remove my collar ties in my Cape Cod attic or at least remove every other one?

I have a quick question about my collar ties that are located on each rafter in my cape cod 1.5 story attic. The collar ties (1.5 in by 5 in) are positioned at 7.5 feet high ( at the bottom of each collar tie) with the apex of roof at 10 foot. The rafters are 2x6 and go all the way down to the eaves. Are these collar ties structural or can I take them out or at very least every other one? Even after taking out every other one I would still have them about every 2.5 feet. Currently they are spaced a tad over a feet apart.

In Building Code Questions | Asked By Michael H. | Feb 6 13
3 Answers

Using hardwood or bamboo flooring planks on walls

I live in climate zone 4a of the United states. I'm having a 3 season sunroom built and would like to cover the walls with hardwood or bamboo flooring planks horizontally over half inch osb or plywood. I have been told that this is doable. My concern is that this room will be unheated. CAN I DO IT????

In General questions | Asked By Wendell Richardson | Feb 5 13
18 Answers

Asphalt shingles, synthetic underlayment, closed-cell foam and buckled shingles

I am just finishing up a home.The roof was installed about 1 year ago.

I have 6-8 inches of closed cell foam on the attic side of osb roof decking(unvented attic). The roofer used synthetic underlayment(grip rite shinglelayment) on top of the osb and then certaintweed landmark asphalt shingles on top of the underlayment.There are garage sections of my roof that do not have closed cell foam used and a more tradional vented attic.

In General questions | Asked By edward lord | Nov 28 12
3 Answers

Insulated Wood Headers

Question about the level of “perfection” that is required for insulating wood headers: Climate Zone 4A, 2x6 exterior walls, and I detailed the headers with the required number of vertical 2x10s (i.e., I didn’t do triple 2x10s in non-load bearing walls). The 2x10s are held to the outside face of the wall. For a single 2x10 condition (~4” void) the insulator was able to dense pack cellulose. For a double 2x10 condition (~2.25” void), I installed 2” of XPS with a half inch gap and foamed in the edges. For a triple 2x10 condition (~.75” void), I caulked the edges for air sealing.

In General questions | Asked By David Baca | Feb 5 13
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