There are factors that are considered when creating a roofing proposal especially on insulation. The IECC changed the amount of insulation that is needed so you must choose the right level depending on your climate zone. Since Polyiso has 5.7 one inch thickness R-value which is the highest when compared to EPS and XPS. This explains why it is one of the most efficient boards for insulation in the market. Every proposal must address puncturing, condensation and ponding as the issues can affect the lifespan of the roof if they are not considered during roof designing.
Condensation – When you avoid condensation, you increase the lifespan of the roof and you protect the interior of your building. Polyiso is an excellent vapor retarder. When you use two layers of the material together with the correct thickness of roof insulation, it works perfectly. The combination prevents thermal bridging and it limits the pathways which moisture uses to travel to the membrane.
Puncturing – Strengthening the membrane is important for two reasons; first, it protects the roof membrane and to provide a substrate where the membrane will be attached. Since you cannot fully guarantee that there will be zero foot traffic on the roof, it is advisable that you have high psi insulation as it is guaranteed to strengthen the membrane thus extending its life. A cover board is needed if your roof has high traffic. Polyiso comes with a high density cover-board. It is lighter than a gypsum board so it offers an outstanding cost advantage. The board also helps in absorbing any impact caused by hailstorm but a gypsum board crumbles when exposed to the same amount impact. The board requires less time, labor and equipment to install when you compare it with other boards and insulation.
Ponding water – Ponding water is water which remains without evaporating for more than 48 hours. The weight of the water can cause the deck to collapse or the water to leak. The water collects debris or dirt and this can accelerate or damage erosion of the roofing membrane. If you want to direct the water to your gutters, you can integrate a tapered polyiso system to your roof design. This increases the life expectancy of your roof.
As a roofer, you need to understand and proactively address the issues as this will result to a good relationship with building owners. The owners will know that you are concerned about their buildings.