I am going to replace of insulation in my house walls. I checked today R-13
insulation at local HomeDepot. There are two kinds of R-13 insulation from
the same manufacturer. The first type is R-13 batts completely encapsulated
into plastic film. I believe the plastic acts as vapor barrier and no
additional vapor barrier is needed. They are sold as continues roll 15" wide
and costs about 26 c / sqft. Another type is Kraft-faced batts also 15" wide
and 8' long, so they are already precut and no additional cuts are
necessary. They are sold in big packs, 8 rolls in each pack. Cost is about
35 c / sqft. I wonder why the first type is cheaper. Since it is fully
encapsulated and sold in much smaller pack it should be more expensive. Am I
missing something here? I think the first one is much easier to work with as
it does not itch. Which type is best for wall insulation?
The plastic is not a vapor barrier , it is so you dont get glassed. Are
you tearing down walls? Rock wool or cellulose can be blown in holes you
cut and repair , cheaper and easier. A vapor barrier must be continous,
vapor will pass where the insulation touches the wood.
Yes, I am tearing down outside walls as I install new windows and have to
enlarge rough windows openings. Anyway even if encapsulated plastic is not a
vapor barrier it makes much more comfortable to work with insulation as you
practically don't need to wear protective clothes as insulation does not
itch. The only concern I currently have is that regular Kraft faced
insulation batts have paper shoulders to staple batts to studs while
encapsulated ones do not and they are probably just laid between studs. Does
this mean that insulation is not completely tight as unstapled batts can
slider down over the time?
Sorry. That plastic is just to protect your hands from the fiberglass.
You still need a vapor barier.
They both work, but the non Kraft type will require a vapor barrier. I
personally think a plastic film barrier is better than the Kraft version,
since most of the time you end up with gaps when using Kraft.
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