In this video we're about to show you
the best practice
insulation install tips around a
standard 90 mm stud brick veneer home
to achieve the best thermal performance.
A perfect video for trades to watch just
before
insulation plumbing and electrical
services are installed in a new build.
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Just so we get a full understanding of
how insulation is going to perform to
its full potential
and get the best value out of it. A
couple of key considerations:
one, is the insulation should be the full
depth of the stud.
So we really want the insulation sitting
out here nice and flush with the front
of the stud.
We're going to be putting our
plasterboard on, our plasterboard is
going to be the second
key to the thermal performance of our
building. It's going to be the air
barrier.
So we want our thermal insulation
abutting the air barrier. What
concerns us is that if we get gaps and
cracks in the insulation,
so if we allow air to transfer from
outside
and then the insulation is set back to
give us an air space,
this is the sort of scenario that will
show up in our thermal imaging
as a lower performing area
of the insulation system. So it's a
matter of
making sure our insulation is
fully recovered, out to the face of the
stud so when the plasterboard goes on,
plasterboard - our air barrier - abuts
our insulation
and we knock out any of that thermal
leak.
Within a wall installation there could
be numerous areas
where the insulation will be performing
poorly, so we're going to have a look at
a number of those. We're also obviously
going to be looking at all elements of
insulation. Up in the ceiling again
we want nice tight fitting batts, we want
them
sitting level with the bottom of the
roof trusses, ceiling joists or roof
beams, so that when we
apply the plasterboard that's our air
barrier and our insulation is abutting
our air barrier fully with no
gaps and cracks - an opportunity for
cold air or warm air to transfer through.
So that's what we're going to be looking
at we're going to go through those
scenarios one at a time,
look at some thermal imaging, just so
it's fully
explained to you at the end of a job,
when a thermal audit
and the auditing process is carried out,
you'll see
what can possibly be poor performing
areas,
so that we can avoid those in the
construction itself.
Let's have a look at one of the
scenarios that i'd like to bring your
attention -
internal walls. You will generally, in
nearly every case, find that this small
cavity here on the outside of the
building
will be completely uninsulated. So
what's going to have to happen here is
as the external building wraps going on,
so in our case in Victoria, cold climate,
will be a vapor permeable wrap.
As that's going on we need somebody to
go along and install these small pieces
of insulation.
They've got to go in all the external
corners
and all the locations where an internal
wall frame meets an external wall frame.
Otherwise these areas here will
show up as a thermal defect.
Moving on to some other areas that we
find commonly, look occasionally there'll
be no insulation where the lintels occur,
but,
commonly we find a bit of insulation put
in there, but there's nothing up here
where the lintel is. While we have
quite a high performing insulation a bit
of
50 mm timber has a very low thermal
performance, so that will show up on our
thermal imaging.
What we would prefer to see is a bat
that's installed
completely, it needs to be checked out it
needs to be installed neatly,
and that's going to give us a much
better result. Again
just to refer to no gaps and cracks,
this is obvious here that there's
insulation sort of poorly installed here,
so
that's certainly going to show up on our
thermal imaging when we audit the
house.
A situation here, where we're using the
off-cuts of the insulation to fill up
one of the stud spacings or a avoid,
this is really not acceptable, again
we've got compression, we've got gaps,
we've got cracks, the insulation is not
protruding forward to be flush with the
plasterboard and our air barrier.
So by the time you put in three or so
pieces of insulation that's about where
we limit ourselves.
At the point of when you're putting six
and eight and ten pieces in,
that is going to show up as an issue in
our thermal imaging.
So now if we look at bulkheads, so it
forms part of our thermal envelope,
what we want to do is make sure that the
insulation is hard up against our air
barrier. So,
our internal plasterboard is our air
barrier, so we
recommend that the bulkhead itself be
fully insulated. So we insulate
the face, the base, the sides of the
bulkhead and we infill insulation
inside the bulkhead so that it's all
pushed hard against the plasterboard
so we maintain that air barrier,
insulation connection.
Just another important comment within a
house, is that there may be
a return air void that is unused, or it
may be a decorative
element of the house that's boxed out, or
the end of a wardrobe
zone / cupboard zone. So what happens in
this case
is we'll have a problem with our air
tightness, because
outside of this void we have ceiling
plasterboard,
providing our airtight barrier, but
within here
there will often be nothing in this
place of the void, so we need to apply
something
at the early stages prior to the ceiling
insulation, that
caps off the tops of these decorative
voids
or unused return air ducts,
ends of cabinets, and so forth to
maintain that level
of air tightness within the house. Now
we're just going to talk from another
aspect of building health,
and it's in regards to your internal wet
areas, bathrooms and laundries.
It's a requirement that not only do we
insulate external walls, because we need
the thermal performance for the building,
we're going to insulate the internal
walls of bathrooms and laundries,
to reduce what we call the temperature
differential which actually reduces
condensation potential.
So if we can reduce condensation to its
minimum risk, we will reduce
mould building up on the inside face of
bathroom walls,
and reduce that health risk to the
building. So again, from a health
perspective,
insulating all the internal walls of wet
areas, to reduce condensation and the
potential of mould.
While the insulation on the inside of
the wall
looks beautifully installed, when we come
around to the back of the wall we start
to look at the locations of electrical
wiring,
you'll see your typical installation of
wiring where it's run through the center
of the stud
compresses the insulation, so we're
reducing the thermal performance of the
insulation in any area where the
insulation is compressed.
What is a better option and our
recommendation is to actually
run the electrical wiring to the back of
the stud,
by clipping it to the rear of the stud,
that allows the insulation to fully
recover,
allowing the full thermal performance of
the insulation.
So there's no erosion of the performance
of the insulation when we clip the
wiring to the back of the stud.
We're constantly talking about the
thermal performance of the building.
One of those areas where the thermal
performance will be interrupted is if
the
switchboard and all the associated
wiring,
is within the external stud frame. So
the requirement is to build a second
stud frame to house the switchboard and
all that wiring,
so that it doesn't interrupt, as you can
see behind, the insulation is
uninterrupted
by all the wiring and work required
around a switchboard.
Another interruption to the thermal
envelope is going to be
all your plumbing, hot and cold water
pipes, in the external walls.
So rather than just installing the
insulation, compressing it around the
pipe, of course
losing some thermal performance, what we
would prefer to do here,
or what's required here, is to make a cut
in the insulation
where the pipe work is, opening it up and
just
encapsulating the pipe work in the
insulation,
so we get the full performance of the
insulation, so it's fully recovered.
So as we referred to with our wall
insulation, about the insulation being
tightly fitting and sitting flush with
the inside face of the stud so when the
plasterboard goes on,
the insulation is hard against our
plasterboard which is our air barrier.
We need to achieve the same result at
ceiling level.
So here commonly you'll see insulation
that's a little up and down,
so we just need to drop them into place
so they're sitting nice and flush with
the underside,
underside of the roof trusses or ceiling
joists,
and in that case, when the plasterboard
goes on, which is our air barrier,
it will be hard to the insulation, there
will be no air spaces, no
gaps or cracks, and the insulation will
perform to its full potential
and the plasterboard will be our air
barrier, which is
hard against the insulation. The plumber
is also going to be running pipe work,
hot and cold pipe work, through the roof
space as well.
Generally he's going to be sitting on
top of the bottom core of the truss, so
when we come to insulate, the insulation
can't go underneath, it'll be lifted up
over the top, so no longer
do we have the insulation abutting the
plasterboard, we have this air space.
So the answer here is to remove the
pipe work from above the top,
sitting on top of the bottom cord of the
truss, and relocate the pipe work to the
underside of the top cord of the truss,
or one of the webs of the truss,
so the insulation can be installed hard
to the plasterboard, abutting the
plasterboard,
so we get the full recovery, no air
spaces, and the performance of the
insulation of the ceiling is continuous
and consistent across the whole house.
So this is a very important one, because
often what we find in most houses,
is that there'll be an equipment
platform, which is housing your
hot water service, ducted heating
equipment, and often we find that this
zone
being of reasonably large area of the
ceiling, will be completely uninsulated.
All we find there is only a 90 mm
bottom cord or truss
with some structure floor or sheet
flooring over the top,
so we only find ourselves with 90 mm of
insulation, when the actual ceiling batts
are
going to be at least two to three
hundred mm thick. So what's required
under your equipment platforms
is to build them up the required height
to accommodate the ceiling insulation
specified.
It's always going to be two to three
hundred mm thick, so these platforms
need to be built up a
lot higher than we typically see, to
accommodate
two to three hundred mm of insulation.
Another critical element to the thermal
envelope
is that you'll often find there'll be a
conditioned room
above a non-conditioned garage, so it may
even be a master bedroom, typically.
So being non-conditioned below, and
conditioned above, we need to fully
insulate the floor zone
between the first floor and the garage.
In this case our airtight
layer is going to be our panel flooring
to the room above. So that's our
airtight barrier. In all cases we need
the insulation to be hard to the
airtight barrier,
so in this case, where you will have
three to four hundred mm of what we'll
call, floor zone,
we need to fill that zone three and four
hundred mm deep with insulation,
so that it's pushed hard against the
underside
of the panel flooring to the conditioned
room above.
This will require not a single batt, but
most likely two batts. It might be
two ceiling batts or a combination of a
ceiling batt and a wall batt,
to fill up that three to four hundred
mm zone,
Making sure the insulation is hard to
the underside of the floor above,
so that we have that air barrier hard to
our insulation zone and
again, it's fully insulated. We're moving
on to cathedral ceilings, where there is
a vertical wall
component, and this wall component is
part of the sealing system. This will
also occur
within things like skylight shafts or
any recesses up into your ceiling and
roof cavity.
So the important fact here is, yes
obviously they need to be insulated,
generally it'll be a 90 mm stud wall. We
need to make sure the insulation that's
introduced into this vertical stud wall
is a high performance batt. So that high
performance batt is going to be a 90 mm
thick
R 2.5 or an R 2.7 glass wool.
Now because it's a vertical wall, there
will be no wall lining to the rear, so
they'll need to be strapped in place, to
make sure that over time, they certainly
do not fall into the ceiling cavity,
and you lose the thermal performance of
the of the batt in the system.
Again, nice and tight flush with the face
of the stud work,
strapped from behind. We are now going to
talk about a very important component of
our roof,
ceiling insulation. This is critical
because
what you'll find is your building
documentation, your energy rating, will
call up
a ceiling batt - it may be a R4 R5 R6.
Those batts are 200 250 and nearly 300
mm thick, so let me show you that if,
in this case this is an R4 200 mm batt.
If I pull that out and imagine that
being installed in a ceiling, you can see
that it
has to be compressed into place around
the eaves,
in which case what it's doing is
stifling any airflow
into the roof cavity. So the requirement
is, that the specified batt
can only be installed to a point where
it maintains
a minimum 25 mm clearance to the
underside of the roof,
for what we call roof ventilation. So
what's the answer? The answer is we're
not going to leave this uninsulated, this
perimeter of the building.
So there's a requirement to introduce a
perimeter batt. Very simply
I'm going to suggest we take a wall batt,
a 90 mm
thick wall batt, now it gets installed
first around the perimeter of the
building,
being only 90 mm thick rather than the
possibly the 200 mm thick of the
body of the ceiling insulation, it sits
in place, and it can be a half batt, so all
the
common batts are cut into a half, so that
it sits around the perimeter
maintaining that airflow between the
insulation and the underside of the roof.
So a perimeter batt, let's call it a half
size batt, half length, followed by your
R4 R5 possibly R6 batt, maintaining that
air space of 25 mm throughout, then we
get nice clean air flow
from the eaves, hopefully there are eaves
vents and ventilation
potential in the eaves itself. You may
have a roof vent at the top, so now we get
that
relief air coming from the eaves and the
roof cavity itself is freely ventilated.
This is critical because there is a
significant health issue,
you stifle air flow to a roof space, you
will build up moisture,
creates condensation and that may very
well
grow mould in your roof. So that's a
significant health issue.
The reason for the perimeter batt is to
maintain the airflow,
to eliminate mould and any health issue
associated with
excessive moisture buildup in the roof
cavity.
In the next video to this series, we are
going to look at achieving the best
level of air tightness using
plasterboard as the air barrier.
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