Icopal roofing underlays
A roof underlay is a layer under the exterior roof that has a primary function of working as the shield that protects the thermal insulation material and the building structure from the effects of the weather.
The roofing underlay has two functions; one, of course, is to function as a secondary roof, when installed under the exterior roof.
Secondly, it must also function as the primary weather shield during the construction period, which, however, should be kept to a minimum time period.
The roof underlay acts as a condensation barrier, which leads condensate water away from the underlay, and thereby also from the insulation material.
Roofing underlay products can be divided into two groups dependent on the roof construction used:
· Ventilated roofs – roof construction that needs ventilation gap over and under the roof underlay, which means that the insulation material never must touch the roofing underlay.
· Diffusion open underroofs – breather membranes that only need ventilation over the membrane, so the insulation material can be just under the membrane.
Product range
The Icopal roofing underlay product portfolio can be divided into two groups of products:
The traditional diffusion tight (no vapour through the membrane), which in general is made up of a reinforcing grid of either polyester yarn or polypropylene, which is protected by two layers of low density polyethylene (LDPE). This build–up could also incorporate an additional layer of spun bond that are either hydrophilic (water absorbing) or hydrophobic (water repellent) dependent of the climate and building traditions.
The second type of roofing underlay in the Icopal product range is the breather membranes which are either made from 100% polypropylene (PP) or from polypropylene (PP) with a coating of special co-polymer plastics. The 100% PP based products composes of a micro porous film in a sandwich construction of protective spun bond.
The second type of breather membranes provided by Icopal is high quality coated products that are from a one layer substrate of PP spun bond add a top coating layer of special co-polymer, which gives the breathability.
All the materials used to produce the Icopal products are from virgin material, meaning no recycled material are used.
Choose the right product
When looking at the tremendous selections available on the market place for roofing underlay it is quite overwhelming to get an overview of this jungle.
However choosing the right product for the right constructions is of up-most importance if it is expected that the product should be working for the life time of the exterior roof, which for the most common roofs is approximately 25 years.
The following conditions most be evaluated before choosing the product:
· What kind of exterior roof is used and can UV (sun light) shine in on the roofing underlay or not
· The construction type must be considered, being a ventilation or non-ventilated construction
· Angle of roof slope
· Duration of the construction period where the roofing underlay will be exposed to sun light - long term or short term.
· Climate conditions should be considered – condensation build-up
· Position of the building, e.g. see site or in land site
Importance of accessories
In order to get the optimal protection out of the roofing underlay it is extremely important to recognize that the installation as well as the accessories used for this is just as important as the membrane itself.
By using the Icopal accessories a total system is formed, which will assist the roofing underlay in being the best possible protection for the total roof construction.