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When you do
the chimney flashing remember to heat up the bottom of the torch
on viapol so that it can bond with the surface. You can heat the
bottom up just before it reaches melting point otherwise the torch
on becomes very sloppy and very difficult to work with. It's best
if the torch on is firm and controllable. In the bottom picture
you will see that the chiminey waterproofing contractor applies
the uni-torch waterproofing membrane between two bricks. If you
torch the uni-torch against the surface of the bricks it will eventualy
pull loose. When water flows down the wall of the chimney it runs
onto the uni-torch and off onto the roof. If you apply the uni-torch
(torch on viapol) against the surface of the brick the water doesn't
run over the torch on but against it and eventualy through continual
rain it will run under it and into your house.
The gas burner
with which to apply the uni-torch has a lever that you can hang
it up with. We hung the gas burner up on a plastic external gutter
on the side of the clay tiles. If you're going to torch on a high
roof I recogmend you use a 9kg gas bottle. The 14kg as well as the
19kg gas bottles can be become very heavy if you have to move it
around on a sloped roof all the time.
Fortunately
the gas burners hose was very long so the contracter did'nt have
to carry this monster gas bottle up the roof.
When Uni-torch
is heated it molds very easily to any shape. Here you can see how
the torch- on is smeered in between the clay tiles profile to ensure
the the water flows smoothly from the top of the roof and down over
the torch-on. Remember that when you do waterproofing you want to
follow that natural flow of water. If the uni-torch is'nt properly
heat fused to the clay tiles the water will run underneath the uni-toch
and into the roof eventualy causing water damage.
Same goes for
when you apply torch-on against the brick wall. The Uni-torch must
be heatfused in between the grooves. That way when the water runs
down the wall it won't run under the torch-on and into the roof
but over the torch-on down the roof and into the gutter.
In this picture
the contractor is finishing off the back corner of the chimney before
waterproofing the back. Make sure enough bituminous primer is applied
to the lead base upon which the torch-on will be heatfused to ensure
that it does'nt come loose .
The Uni-torch
must be taken back onto the second batten and fixed with clout nails
to ensure that no water will leak in any where. If you cut a piece
400mm wide you should be ok. Make sure you fix the torch-on with
clout nails though becuase you don't want it to come loose while
the tiles are ontop.
Finishing off
the back of the chimney corner properly is also very important.
All the water flows from the top of the roof down against the back
of the chimney so the back must be very watertight. The idea of
the 400mm torch-on piece behind the chimney is that if the water
collects behind it that it will flow down the sides away from the
chimney.
After the torch-on
is complete and you're sure that no water will leak into the chimney
you can pack the tiles back.
To finish off
the waterproofing of the chimney you can either paint a UV reflectant
aluminium paint called silvakote or acrylic st which is a weatherprufe
product. Acrylic st the only paint that sticks to torch-on. We even
use it as a primer if we want to paint the torch-on a different
color.
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