Multipul layers of house wrap?
rexw...@gmail.com
T111 with house wrap underneath. Since the existing siding is still in
decent shape I am thinking about siding right over it. Can I put
another layer of house wrap over the top of the existing siding before
installing my new siding (e.g., will it hurt to have the original
siding sandwitched between two layers of house wrap)? I live the
Tongas Rainforest in Southeast Alaska which, needless to say, is a very
damp place. Thanks for your help.
m Ransley
BP
<rexw...@gmail.com> wrote in message
news:1141189093.6...@j33g2000cwa.googlegroups.com...
Housewrap > T-111
or
Studs > Housewrap > T-111?
Rich-out-West
home. The exterior walls were 2x4 studs sheathed with 4x8 sheets of
Lousiana Pacific lap siding. In other words, the siding panels were
structural. This siding was failing badly in places due to moisture.
This was the same stuff involved in that huge class-action lawsuit a
few years back. The fix we arrived at was to remove any siding that
looked suspect (about 25%) and replace it with 3/4" OSB. We then
housewrapped the entire house and hung vinyl siding. We were very
careful to detail the door and window openings properly - this is key.
This approach worked out great. I'm quite confident that the
installation we ended up with was better than the original siding job.
By the way, this place was in Union, WA, just down the road from
the rainiest spot in our state. It was damp there all winter long. We
made a point of doing this work during summer when the siding was good
and dry. To those who say you're going to trap moisture, I'd ask what
happens when you put housewrap over the sheathing on a new house? Your
T111 is basically plywood, so if it's not rotten, and it's not dripping
wet, it will probably make a decent base for your new siding.
Richard Johnson PE
Camano Island, WA
Dennis
permanence several times that of the interior barrier, say around 5 perms or
higher. There are plenty of housewraps on the market that are designed to be
'breathable, that is, they block infiltration but allow moisture to escape.
(Such as R-Wrap and the like.) This is the type of product you would want
to use.
As others have stated, do not use a non-permeable type wrap as it will slow
the release of moisture from inside the walls and cause additional problems
such as lower insulation values, mold, mildew, rot, etc. (T-111 with an oil
based paint is a vapor retarder already, don't make it worse.)
Dennis
<rexw...@gmail.com> wrote in message
news:1141189093.6...@j33g2000cwa.googlegroups.com...
rexw...@gmail.com
> cedar siding. The rest of the house is studs with house wrap and then T-111.
BP
<rexw...@gmail.com> wrote in message
news:1141262703.1...@i40g2000cwc.googlegroups.com...
> Actually both. The front of the house is studs > sheathing > housewrap
>> cedar siding. The rest of the house is studs with house wrap and then
>> T-111.
>
as a housewrap and side right over the T-111. The felt tests better than
housewrap for vapor transmission and is cheaper to boot.
Dennis
Type-I Underlayment at 5 perms, ASHRAE Fundamentals lists it at 1 perm
dry-cup and 5.6 perms wet-cup. But comparing this to a specific product
like R-Wrap (chosen due to familiarity, many similar products available)
which has a WVT rating of 59 perms, it's easy to see which products will
allow water vapor to pass through the wall faster.
Also these products are much lighter weight and have superior strength in
tearing (a real plus if you have ever attempted to hold a roll of felt
vertically on a ladder only to have it tear in half before it was fastened
(experience talking). Personally I would still recommend the house wrap
over felt for these reasons.
BP
"Dennis" <nob...@verizon.net> wrote in message
news:u4FNf.32798$%v4.11505@trnddc03...
> Hadn't thought about felt as a wrap in years. Checked in ASTM and they
> rate Type-I Underlayment at 5 perms, ASHRAE Fundamentals lists it at 1
> perm dry-cup and 5.6 perms wet-cup. But comparing this to a specific
> product like R-Wrap (chosen due to familiarity, many similar products
> available) which has a WVT rating of 59 perms, it's easy to see which
> products will allow water vapor to pass through the wall faster.
>
> Also these products are much lighter weight and have superior strength in
> tearing (a real plus if you have ever attempted to hold a roll of felt
> vertically on a ladder only to have it tear in half before it was fastened
> (experience talking). Personally I would still recommend the house wrap
> over felt for these reasons.
>
that was published in The Journal of Light Construction. What they found was
there are lies, damned lies, and statistics. Their tests showed that tar
paper was 3 to 4 times more permeable in real world conditions than the
housewraps, contrary to the data provided by the manufacturers. The
manufacturers of housewraps have some geeks on board that have fun with
math. See if you can find the article, it's an interesting read.
Unfortunately, JLC wants you to pay to read their back articles.
Wayne Whitney
> The University of Massachusetts did an independent test a few years
> back that was published in The Journal of Light Construction.
Do you mean this article:
Cheers, Wayne
BP
"Wayne Whitney" <whi...@post.harvard.edu> wrote in message
news:slrne0em4k....@pizza.private...
That's the one!
Dennis
was on grad student, and what he wrote was "Our test results showed that
after a series of 2-hour test runs, clean water never leaked through Tyvek
or R-Wrap; 15-pound felt lost 30% of its water on average", & "Based on our
testing, if I were buying a housewrap today, I would choose either Tyvek or
R-Wrap, because they display the best water resistance" & "As it happens, I
have felt paper on my own home, and if I could choose between felt and
housewrap and do it over again, I'd still choose felt. That's because I
believe that under certain circumstances, felt outperforms housewrap."
Notice he is injecting opinion without subjective facts. Point in face is,a
good housewrap is better at preventing water penetration than felt, and it's
stronger and lighter, more tear resistant.
I especially got a good laugh about this ridiculous statement "And since
housewraps are vapor permeable, they can allow vapor to pass into the
building envelope from the outside." As if that was the real problem. In
fact the real problem is moisture from cooking and bathing getting OUT (not
in). Failing to get out in the winter is where the problems occur. With high
indoor humidity's and low exterior humidity's, it would be very unusual that
the exterior moisture would be trying to get 'in'.
In any case, I don't give this fella a lot of credence. While caulking isn't
perfect, it have been proven over the decades to be a reasonably effective
(consider how windows were caulked and lasted for decades.) As he's against
caulking (inc. silicones) he just put the roofing industry out of business.
Officially ASTM list felt at 5.6 perms when dry. It goes up to a level
equivalent to R-Warp in periods of high humidity. So, where's the "lies and
damn lies"?
Felt will do the job Ok, just a pain to work with compared to the new
housewraps.
(Wasn't aware that the other leaked so bad however, good facts to learn.)
Dennis
BP
seen the stuff before. It was 1980 or 81. Back then it was basically just a
plastic sheet. The crew and I had serious reservations using the stuff. We'd
show up in the morning and the plywood behind the Tyvek would be soaking wet
from condensation. But the customer insisted so we finished siding and
forgot about it. But I never wanted to use the product again. Figured it
would be just another one of those great product ideas that come out with
fanfare and then just slink quietly into the shadows. But no! A couple of
years later a salesman shows me the new, improved Tyvek. It's the same
plastic sheet, but now it's got perforations, little pin holes, every 1/2
inch or so. "This stuff breathes" I'm told. "I thought it breathed before" I
ask? "Oh, well, they had a problem with that..."
A couple of years later they came out with the stuff we know and love today.
A weave of loose fibers. I became a convert when I discovered that I could
weather-tight a house and start insulating while I was waiting for the
siders to not show up. Never looked back at red rosin paper again.
Doing remodeling you notice some interesting things. Things you see on
older, pre-tyvek houses. Things you see on post Tyvek. Observations in the
field. We speak not of these things, as they may negatively affect the
construction schedule. And as for you, dear reader, this is all just
anecdotal BS from an old goat who still can bang 16d common nails. You will
believe what you want.
"Dennis" <nob...@verizon.net> wrote in message
news:3p4Of.1049$_A4.134@trnddc06...
3D Peruna
There's lots of good stuff there...interesting things about housewrap
and felts and all that stuff.