working with unfaced batts


Old 09-11-06, 01:38 PM
Thread Starter
Join Date: Jul 2003
Posts: 54
working with unfaced batts

I am finishing my basement and will be using unfaced R11 or R13 batts in the perimeter walls. The walls themselves are typical 2x4, 16" on center construction. Between the framing and concrete foundation I glued in 1" extruded polystyrene foam panels. I know with the faced batts, you staple through the paper flange into the stud. With the unfaced batts, how do you keep the batts from sliding down over time?
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Old 09-12-06, 05:41 AM
Join Date: Feb 2006
Location: USA
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Unfaced batts

These are intended for horizontal installation. Vertical insulation needs the flanges to staple to the studs.
Old 09-12-06, 06:31 AM
Join Date: Feb 2002
Location: US
Posts: 357
Friction Holds the Batts in Place

Unfaced batts can be and often are placed in vertical stud bays.

Provided the stud bay is the same width as the batt the batt is simply held in place by the friction between the bat and the side of the studs. It will not slip down over time.

If you are asking this question, then I suspect your framing might be a little off causing the batts not to remain in place.

You could buy insulation support wires (usually used to hold insulation up between joists in areas such as a crawl space) and put them horizontally through the batt to hold the batt up.
Old 09-12-06, 07:14 AM
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Join Date: Jul 2003
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My framing may be off in some areas, but also what concerned me is the fact that in other areas, there's a considerable gap between the foam and the framing (due to plumbing and other obstacles). So in side to side direction I may have a friction fit between the studs, but in the depth direction, there will not be anything in the back to compress the batt.

I will have a look at those wires. If I understand you correctly, I poke the wire through the middle of the thickness, and then the ends of the wire grab the sides of the 2x4's?

How may wires per stud bay would you say? Maybe one a few inches down from the top and another a foot or so down?
Old 09-12-06, 09:41 AM
Join Date: Feb 2002
Location: US
Posts: 357
Trial and error

I apparently misunderstood what you were concerned about. I thought you were having issues with the batts fitting in side to side or between the studs.

It now looks like your worried that the batt will push out the back toward your basement wall.

Just try to keep the face of the batt flush with the finished side of the 2X4. The backside of the batt toward the foundation wall will not protrude hardly any at all in that direction and if it does, it will not be an issue. This of course takes into account you have batts that are designed for 2x4 walls and not 2x6 walls.

If you need to use the insulation wires to help hold a batt up, it will just have to be trial and error. Start with one at the top a couple of inches down and see if that will provide sufficient support, if not, add another a foot below and so on.
Old 09-12-06, 09:59 AM
Ed Imeduc's Avatar
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389

You might find that if they dont fit real tight to stay put a dab of glue on the poly on the wall. Or cut the batt so it will fit sideways in the stud or cut a strip piece to fill in so it is tight in the stud. Dont forget when done put a 4 mil poly over it all then the dry wall.
We use the unfaced batt for the stud walls most of the time with the poly over them works a lot better than the paper back

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