John: Today I'm with Berkhard from CARBONlite.
We're going to talk about good practice
for weather resistant barriers and
common practice for weather resistant
barriers. Berkhard, we've got a common sort
of installation and sarking here. What
are the issues with this? Berkhard: Well here we've
got a scenario which could be built to
common six star rating - if you like. So you've
got a non diffusion, non-permeable sarking
in this scenario the main aim is to keep
the weather out and make make it wind
resistant and weather resistant. But
as you can see here, most of the joints
are not sealed. Then you've got the
joints around the window, the gaps around
the windows, are not sealed. If they're
sealed, sometimes you see them
sealed really poorly with duct tape, lasts
about a couple of weeks and all come off.
And like just lasts long enough for the
cladding to go on. It's it's not a
solution that will last for decades. John: So
that that's with the junctions around
windows, but also with how they're
overlapping potentially as well, or if
penetrations go through, you know, nothing
is really continuous. Berkhart: No, there is no..
you can see some of the gaps around the
windows here are all open. So it's, it's just
not even .... we're not even talking
about high performance,it's just simple
rain actually getting into the structure.
So you won't just have your reduce,
massively reduced thermal performance of
the house, you will also actually have
water getting in, and resulting in
structural damage, and rot and mould.
John: All right then, let's move over now to
good practice. Okay Berkhard, so this is
now good practice with a membrane. Show
us have this differs from what we just
saw.
Berkhard: Yeah, so if you imagine this wall is
perfectly sealed, weather-tight and wind
resistant with the membrane continuing
through. Now if we start cutting a
hole into it, we would have to recreate
that connection to our window. In
the conventional construction you
saw that on the other side, it's just cut
flush with it the subframe opening. So
there's no tape, there's no seal
connection, there's no water tight
connection. So water has got unrestricted
access to the building. Now in this
scenario here, we're creating, on the
bottom we're creating, a seal flushing
before installing the window. Then the
window frame is prepared with the
double-sided tape, okay, so that tape is on
the window first, simple installation and
then we're folding it and taping it onto
the membrane. Now we've got a completely
sealed weather-tight and diffusion-open
connection to the window, and we can rely
on this membrane to keep the weather out
before cladding goes on. John: So for this
weather resistive barrier,
let's hit it with the hose, and see how
both sides perform. So Berkhard, we're
simulating 30 km/h winds on
this enclosure right now, which is blower
door testing. Let's hit it with some
water and see if, how much of it goes
inside. Berkhard: Yep.
We've got two settings, so I'm just going
to put a light rain, so I mist, and
then we're moving on to a bit more pressure. Real life
scenario, you know, we don't want to... John: You
can clearly feel airflow around this
window, especially on the sides too, right?
Berkhard: Yeah, and it's 30 km/h winds, you
know, it's not anything outrageous
we're talking about. John: And if this water gets
in, all the insulation under the window
is going to get saturated. Berkhard: Well it's not
just the insulation that it's, the most
concerning part are the structural
components in there. So if the structural
components start being wet inside
inside their wall, then you've got a
non diffusion of the membrane and all of
a sudden you closing that moisture into
the wall structure and and that really
results in in structural damage, you know?
That's a real concern. So this is now the
shower function, so a bit heavier rain
right? John: Yep.
Berkhard: That's that's heavy rain, right?
We're trying to showcase the point here.
John: Okay, let's check out the other side with
good practice.
Berkhard: Yeah, let's do it.
John: Okay, Berkhard, now without hosing me down,
let's see what this one does. Berkhard: Alright,
well just got this on mist alright, so
we're just trying to do it, we're going to
do a couple of runs. One in like light
mist, and then a bit of heavier rain. John: Yep!
Berkhard: Okay.
So we're just trying to get a realistic
scenario off to the decent rain, and
we can also set this at a higher... John: I mean you
can see that it's the water's just not
going anywhere, right? Berkhard: No, it's just it's
just running off. I mean, it is just doing
what it's supposed to do. This thing is
this is completely sealed. There's
no problems at all. And this is not just water,
this is also wind obviously, as well.
John: Alright so now let's go and have a look
inside. Using amazing building materials
is only part of the story. The most
important part of constructing a
building, is making the important
connections for air tightness and
weather-proofing. If you think this
footage doesn't show common practice
well enough you should take a drive
around any major construction site in
Australia. You'll find many examples of
exactly the same level of workmanship.
When we talk about building for a better
seal, we're not talking about sealing up
houses so that people can't breathe.
We're talking about keeping our homes
dry from rain, and from rotting from the
inside and the outside. We want to
protect the occupants by providing good
ventilation, and proper sealing. Build
Tight and Ventilate Right. The future of
residential building in Australia will
be strongly influenced by consumer
demand for energy efficiency, comfort,
climate resilience and quality. But the
Building Codes Board and Australian
Governments are committed to the COAG
trajectory for low energy buildings and
this will affect building regulations
including the NCC. Builders will be
expected to place increased emphasis on
meeting and proving
energy efficiency compliance. You'll be
asked, more and more, to understand and
deliver both code compliance and
long-term building health and
performance. You will need to Build Tight
and Ventilate Right.