The problem of Condensation
Un-insulated roofs with single skin metal sheeting
are likely to suffer from condensation when the metal
sheeting is cooled during the winter, or on cold clear
nights.
When warm air within the building cools on contact with the
metal sheeting, the air cannot support the same quantity of water
vapour, and becomes saturated, with any excess water
vapour condensing on the underside of the sheeting.
This
condensate can drip from the roof, wetting the building's
fittings and/or contents, or may run down the roof and
collect elsewhere within the building fabric, where it can
cause rust, rot or damage to fittings.
On
frosty nights, particularly with the white Hoare frosts, the
condensate freezes overnight and then next day as the day
warms up the now substantial condensate drips onto the
contents of the building wetting them sometimes in a
considerable way.
Drain Dripstop and a
similar product from another manufacturer has been supplied
by SLE Cladding Ltd for a considerable number of years, and
during this period we have not received a single complaint
about its performance, bearing in mind that both the winters
of 2009/2010 and 2010/2011 have both had very severe periods
of weather by UK standards, so it must work.
Condensation is the most common form of dampness encountered
in buildings and Part C2 of the building regulations require
designers to prevent harmful condensation forming on or
within building elements. Guidance is given in BS 5250 2002.
The Drain Dripstop Solution.
Made from
interlaced PES fibres, Drain Dripstop slows the formation of
condensate by insulating the sheet and prevents dripping
from the underside of the roof by absorbing the moisture and
draining it down through its fibres to the gutter.
The Benefits of Drain Dripstop
Slows the formation of condensate by insulating
the sheet.
Prevents
condensate dripping from the underside of the
roof.
Drains condensate safely down the slope of the
roof to the gutter.
Can easily
be cleaned with a pressure washer. |
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Drain Dripstop is available in the AS 30 box
profile and
AS13 x 3" corr as per drawings below.
The fleece is
applied to the sheeting during the profile
manufacturing process |
1. Profiled top sheet.
2. Profiled lower sheet
3. Fixing Screw.
4 Drain Dripstop fleece
5. Velcro packer (if required)
6. Condensation |
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Design Guidance
Drain Dripstop is suitable for use on roof
slopes greater than 7 degrees and the greater
the roof slope the faster the moisture is
drained from the sheet. Drainage performance of
the material per hour for a range of roof slopes
is shown on the right |
Property |
Roof Slope |
Water drained out |
Outflow of
water
after 1 hour |
7% |
10% |
|
15% |
15% |
|
25% |
25% |
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Drain Dripstop controls condensation in an
environment
where it appears cyclically (it can't prevent
condensation).
For the membrane to work properly the building
has to be adequately ventilated to allow the
material to dry out between the cycles. (see
diagram on the right) |
Eaves ventilation
required = 2% of roof slope area
Ridge ventilation required = 5% of total roof
area |
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In buildings with poor ventilation or
humidity levels greater than 80g/m2/hour, roof
sheet lengths should be reduced to control the
amount of moisture handled by each sheet. |
Roof Inclination |
7% |
14% |
21% |
|
Recommended Max panel length |
3m |
5m |
7m |
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The table opposite shows moisture levels
produced by livestock and the area required by
each animal to keep humidity levels below
80g/m2/hour |
Animal |
Weight |
Moisture produced |
Area req. per
animal |
|
Cows |
500kg |
361 gm/hr |
4.51 Sq/m |
|
Horses |
500kg |
361 gm/hr |
4.51 Sq/m |
|
Sheep |
100kg |
83 gm/hr |
1.04 Sq/m |
|
Pigs |
100kg |
83 gm/hr |
1.04 Sq/m |
|
Chickens |
2.2kg |
5.5 gm/hr |
0.07 Sq/m |
|
Temp 16 - 18 Deg.
80% relative humidity |
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| Installation
of sheets fitted with Drain Dripstop
condensation control fleece is the same as for
standard sheets. However when humidity levels
are greater than 80g/m2/hour or ventilation is
poor, velcro packers or similar are required at
fixing screw positions on purlins and in end lap
joints to allow the moisture from each sheet to
drain out onto the sheet below |
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CUT EDGES
and CUT BACKS.
The
manufactures state that due to the fleeces composition there
is no need to cut back the fleece or to apply "Cut
Edge Protection
Lacquer" at the lower end of roof sheets. SLE Cladding would advise
the use of "Cut Edge Protection Lacquer" in
marine environment, coastal regions and corrosive industrial environments.
MAINTENANCE
When used in livestock buildings Drin Dripstop should be
pressure washed at least once a year with a solution
containing a fungicide
PROFILES,
COLOURS and THICKNESS AVAILABLE.
Manufactured to required lengths in the standard range of
colours in 0.5mm and 0.7mm substrates
in 30/1000 box profile and 13 x 3" corrugation as per below.
Manufactured to order.
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