It only takes common sense to understand that housewrap will restrict
airflow to the substance it surrounds. Put your hands in your pockets
when the cold wind blows and see if your pants material will block the
elements. Whether it blocks moisture who really cares, if you have
that much moisture where it can soak the housewrap, you have much
larger problems because you are probably in an area that is prone to
flooding or hurricanes.
I would say that housewrap is less necessary in warmer climates.
Spec-Home builders skimp on a lot of things to make more money and not
wrapping is just another way, like using single pane windows or poorly
rated appliances. I would never buy a completed spec home unless I
knew the builder had a good reputation.
In a properly built house water does not pass through the siding to
the sheathing. Siding is constructed to have the water run off.
Thousand, ten thousands, even millions of house shed water perfectly
before tyveck was invented. Lots of house still don't use tyvek, and
if you price a roll, you'll see why. Besides, carpenters often ruin
the tyvek, even the sheathing, and never properly repair it, making
the tyvek only partially effective in reducing air movement through
the home. BTW, the purpose of tyvek is not to shed water (although it
does), it is to reduce air flow without completely stopping the
movement of gaseous water. I would prefer my house to be wrapped in
tyvek, but if it isn't I would get too upset. No house built before
?1970? used tyvek.
Tarpaper works good as moisture barrier and was ok in air leaky shacks
which allowed any accumulated humidity to be removed, but you wouldn't
want to use it under the siding in a modern house because moisture
would be trapped inside the walls.
Jeff Six wrote:
He has some points, but he is basically full of crap about the purpose
of house wraps; house wraps are designed to limit air infiltration
without eliminating movement of gaseous water. The purpose of the
siding is to limit or eliminate water penetration to the structure.
The very outer layer needs some ventilation and drainage to get rid of
any water that does penetrate the siding. Whether a house has a
housewrap or not, it needs to be constructed to limit water
penetration past the siding. There are many houses that have stood
for hundreds of years because they were constructed to
reduce/eliminate moisture penetration without house wraps and calks.
You construct a house the same way whether you use a house wrap or
> > > In a properly built house water does not pass through the siding to
> > > the sheathing.
> > False.
> What's false? What IS the purpose of the siding?
What is false is that a properly built house will not allow water to pass
through the siding
> > > Siding is constructed to have the water run off.
> > > Thousand, ten thousands, even millions of house shed water perfectly
> > > before tyveck was invented.
> > If ten thousand people jump off a bridge, it doesn't make it right
> That doesn't make sense. Are you suggesting people shouldn't have
> built houses before Tyvek was invented?
It makes sense, you just chose to ignore it.
> > > Lots of house still don't use tyvek, and
> > > if you price a roll, you'll see why.
> > the new issue of IBC will make it a requirement.
> Are you implying that Tyvek will be required by all local building
THe existing code required building felt or other approved materials (i.e.
tyvek) my understanding of the new code to be issued will require a tyvek
> > > Besides, carpenters often ruin
> > > the tyvek, even the sheathing, and never properly repair it, making
> > > the tyvek only partially effective in reducing air movement through
> > > the home.
> > Poor construction practices (by some) is NEVER a reason to not
> > material.
> No one said it was. Just stating a fact about poor construction.
No, you were implying why not to use it.
> > >BTW, the purpose of tyvek is not to shed water (although it
> > > does),
> > False, the tyvek is an air infiltration barrier and a secondary
> > barrier
> And I didn't say that the purpose was an air infiltration barrier?
Reading comprehension is not one of your strong points is it......what
part of AND don't you understand
> > >it is to reduce air flow without completely stopping the
> > > movement of gaseous water. I would prefer my house to be wrapped in
> > > tyvek, but if it isn't I would get too upset. No house built before
> > > ?1970? used tyvek.
> > No, they used building felt for the same purpose, but it wasn't as
> > >
> > > Tarpaper works good as moisture barrier and was ok in air leaky
> > > which allowed any accumulated humidity to be removed, but you
> > > want to use it under the siding in a modern house because moisture
> > > would be trapped inside the walls.
> > False
> Oh? a poorly constructed or damaged moisture barrier on the inside of
> the wall and an effective moisture barrier on the outside of the wall
> wouldn't lead to moisture trapped in the wall?
Building felt was never sealed, i.e. taped........vapor pressure was not
trapped by it. It was a decent moisture barrier from the outside if
properly lapped. therefore it was not a true moisture barrier from the
inside.......you really don't know what you are talking about.
> > >
> > > Jeff Six wrote:
> > > >
> > > > I have recently discovered that my house (I've been there a little
> > > > over two years) does not have housewrap underneath the vinyl
> > > > Underneath is OSB sheathing and the vinyl is installed right on
> > > > the OSB. This is true of all of the houses in my development.
> > > > looking around the newsgroups, I find the while housewraps are
> > > > recommended, there appear to be tons of houses that have this same
> > > > situation - vinyl siding installed directly over the wood/OSB
> > > > sheathing. After some rain, I've popped the siding a little so I
> > > > see under and don't see any rain or moisture on the OSB.
> > > > Nevertheless, the paranoid in me is concerned.
> > > >
> > > > I'm really looking for some reassurance here that this situation,
> > > > while not the best in the world, is OK. Little help? Thanks.
I think you just like to argue so I selected just one part below to
Paul Fritz wrote:
If you put a moisture barrier on studs or over sheathing, overlaping
the pieces by 6-12 inches, and then nail siding on, the moisture
barrier will be sealed by the pressure of the siding against the studs
or against the sheathing. T-11 siding will really seal it, but so
will shiplap or any other real wood lap siding.
> I think you just like to argue so I selected just one part below to
> comment on.
> Paul Fritz wrote:
> > > > False
> > >
> > > Oh? a poorly constructed or damaged moisture barrier on the
> > > the wall and an effective moisture barrier on the outside of the
> > > wouldn't lead to moisture trapped in the wall?
> > Building felt was never sealed, i.e. taped........vapor pressure was
> > trapped by it. It was a decent moisture barrier from the outside if
> > properly lapped. therefore it was not a true moisture barrier from the
> > inside.......you really don't know what you are talking about.
> If you put a moisture barrier on studs or over sheathing, overlaping
> the pieces by 6-12 inches, and then nail siding on, the moisture
> barrier will be sealed by the pressure of the siding against the studs
> or against the sheathing. T-11 siding will really seal it, but so
> will shiplap or any other real wood lap siding
A. it will not be sealed, thus allowing water vapor to escape. Also,
older homes were not sealed as well........poorer construction, leaky
windows, doors etc, so building felt acting as a vapor barrier was not as
critical as it is today.
B. Tyvek is a superior product which is why the code is moving toward
requiring it. Just as a ball point pen is superior to using an ink well.
You continue to show you don't have a clue to what you are talking about.
That's wrong. One of the very earliest basic tech classes from when I
was in architecture school, stressed that the building paper (this was
before Tyvek) was what really kept the water out of the house, and
that the siding mainly protected the paper. Take as an example a
brick veneer wall where the brick is the "siding". The brick is built
a small distance away from the sheathing and there will be weeps at
the base of the wall to let water out. The people who built tarpaper
shacks knew which layer kept the water out - beter to skip the siding
than the tarpaper!
The reason Tyvek was an advance is that it still deflected liquid
water (like tar paper before it) but it let vapor pass out of the
house and not condense and freeze inside the cavity (more important
now that houses are better insulated).
It's not wrong with regard to water impenetrable surfaces such as
metal and plastic, and not wrong when applied to well painted wood
siding, even unpainted shingle and shake siding. Sure, people used
tarpaper to keep the water out, it was cheap compared to putting
siding on. People skipped the siding because of poverty not because
of something else. Everyone wants to argue about brick walls, but
water seeps through brick, so you need drainage holes. Brick is great
for long term wear, but the multitude of joints leads to water
penetration, so construction needs be in accordance. Wooden shingles,
for instance, shed water. Hell, I use to see light through small
cracks in shingled roof of our house (no ceiling in the upper story)
when I was little but rain and snow never penetrated. There was no
tarpaper between the shingles and the wood structure. Heck, how old
do you think tar paper is?
Sure is does those things, but the marketing is for reduction of air
flow. Most houses that I see constructed without Tyvek do not have
any kind of wrap and certainly tar paper is never used as a wrap.
Small pieces of tar paper may be placed at strategic points around
window and door openings and much of the sheating is water repellant,
e.g., foil covered foam. But the plywood pannels used for strength
are never covered with tar paper. Of course exterior plywood is used
and the glues are water repellant. However, I don't see any treatment
of the joints between pannels. If water penetrates the siding it will
wet the sheathing, the frame, and the wall insulation.
Most house are made of wood which just naturally rots. But poor
construction, poor design, poor materials, etc. sure help it along.
The point, however, is that many houses are still functional after 100
years and were designed and constructed to shed rain, snow, sleet, and
hail when house wraps and house calks were unknown.
You cannot build like they did yesterday and meet today's codes.
One of our buddy Joe's favorite lines is "...energy conservation has the
potential to destroy more buildings than architects."
If we built like they built 100 years ago, I'd agree. But if you build to
meet current energy codes with standard building materials using typical
craftsmanship, you'll build a house that rots away in 10 years. Changes in
the energy usage requirements have (and changes in building codes -- like
the ones in Minnesota) mandate a change in the way buildings are constructed
if you want them to last 100 years.
Those changes require managing moisture from the interior and the exterior.
If you assume things are going to get wet, then provide a way for them to
dry out. Housewraps and building felt (which isn't inferior to housewraps
in many applications, in fact, it's better in several) are one of the pieces
in the water management system of a building.
Personally, I'm looking towards different materials and methods...and I'm
not an environmentalist nut, either. I try and design buildings that will
last 100 years AND are affordable to build AND look good. As part of that
design, I use building paper and housewrap, carefully considering what is
appropriate for each situation.
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