Faced insulation in Florida
Last Post 17 Feb 2016 08:20 PM by agagent3. 4 Replies.
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agagent3User is Offline
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15 Feb 2016 09:20 PM
Originally from Wisconsin where the Kraft paper on faced insulation goes behind the sheet rock. Vapor retarders are place opposite of cold climates in hot, humid climates. A big box store has a sale on faced insulation. Would it be correct to install it so that the Kraft paper is next to the outer sheeting? Or should I go with unfaced fiberglass insulation?
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16 Feb 2016 11:17 AM
With kraft facers it doesn't matter- it's a smart vapor retarder, and would not trap moisture in the wall, and putting it on the interior side is just fine. The vapor retardency of half-inch OSB or plywood is about the same as the kraft facer when both the sheathing and kraft facers are dry.

But with foil facers you'd have to put the foil on the exterior in FL.

The most important thing for both a mold-hazard and thermal performance point of view is to AIR SEAL the framing to the sheathing in every stud bay before insulating. Moist air convecting through the batts in an air conditioned house could end up with mold inside the cavity or even blistering peeling paint on the interior if the leakage is severe enough.
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16 Feb 2016 03:10 PM
Thanks Dana1,
I will caulk all every stud bay, I think I will apply the Kraft face towards the outside sheeting which is TG1-11. I have done my own comparison of 8 different calks in which I applied the calk on some test boards leaving them to dry in the sun for a week and found I like the Home Depot brand HDX Latex Plus Silicone the best. Are there other choices that are sure fire winners for the application I intend?
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16 Feb 2016 04:57 PM
A purpose made sprayed caulk such as Knauf EcoSeal or Owens Corning EnergyComplete works great for air sealing quickly, but the equipment costs are daunting.

In hurricane country (that's all of FL) caulking the T1-11 to the framing with polyurethane construction adhesive has a lot of merit. It stiffens up the assembly considerably from racking forces, and makes it far less likely to peel apart under heavy wind. In heavy earthquake zones that's sometimes disallowed, since it makes it more likely for the house to walk off it's foundation during an earthquake, but in FL wind zones the extra stiffness would be a plus.

If you have a lot of walls to do all at once, it's worth springing for a powered caulking gun.

Be sure to can-foam seal all wiring & plumbing penetrations of the sheathing AND the framing (at every stud bay for lateral wiring runs.) Don't forget to caulk the seams between any doubled up studs headers or top plates, and between the bottom plate an the floor/subfloor.

T1-11 with an exterior grade paint has a vapor permeance less than 1- perm- the additional vapor permeance of the facer isn't buying you anything when it's adjacent to the sheathing. It's easier to install kraft-faced batts properly when the facer is on the interior side, since the folded over tabs make it hard to properly tuck the corners and edges for a complete fill. Faced or unfaced, pushing the edges of the batt to fully fill in the angle where framing meets sheathing is key to getting the full performance out of it. That usually requires pushing it in to where it's compressed, and not quite reaching the interior stud edge, then gently tugging it back until it's just proud of the stud edge. The tabs should be on the face of the stud edge, not pressed in and side-stapled, which would leave a small vertical gap increasing the thermal briding of the framing and providing an unimpeded air movement path.
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17 Feb 2016 08:20 PM
While I have the wall cavity open does appling a vapor retarder paint on to the exposed TG1-11 get me anything?
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