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Keep Your Commercial Roof Humidity Low

Humidity is a huge problem for plenty of construction material. Moisture can weaken supporting materials and concrete upon infiltration and left unattended for months or years. Over time, wooden components will start to shrivel, rot, and grow molds. Single-ply materials can turn brittle and lose their adhesion.

Torch-down bitumen roofing can also be affected by high humidity. The hot, humid air can expand the bitumen material, allowing moisture to infiltrate it. The material shrinks during colder months and expands again during warmer temperatures, causing the moisture to turn to vapor and cause blisters on the roof material.

Some rubber roofing materials are susceptible to mold growth. These colonies of mold grow in humid areas. Over time, they will infest the rubber and accelerate its degradation. Single-ply roofs with organic materials may endure damage due to mold growth.

The best way to keep your roof humidity low is to have regular inspections. This will reveal if your roof has leaks that lead to high humidity and mold growth. Furthermore, you can extend your roof's lifespan with frequent checks.

Here are a few more things to know from Enviroply Roofing.


For single ply roofing, there are a number of things that can be done to lower the risk of condensation. For warm roofs and cold roofs the considerations are different, as each type of roof is built in a different way. But to begin, relative humidity calculations will be used to develop the roof, helping to determine the positioning and size of the vapour control layer, as well as any necessary adjustments.


A warm roof is designed with the insulation over the top of the roof deck, on top of a vapour control layer, and underneath the roof covering. So, to tackle any humidity and to prevent condensation, you should:

  • fill any gaps in the insulation to prevent cold air bridging
  • avoid air movement through the roof system, preventing cold air from travelling
  • use an appropriate vapour control layer, and install this correctly


A cold roof is designed with the insulation between the rafters, so its important that the air can circulate, to reduce any humidity issues. This means you should:

  • leave a minimum 50 mm gap between the top of the insulation and the underside of the roof deck
  • install adequate ventilation at each end of the roof


For high humidity environments, these considerations will not be enough. For swimming pools, sports halls, large commercial kitchens, and other areas with obvious high humidity, you will need to take additional measures. And this also includes buildings like schools and community halls, that may be heated intermittently, but then closed and unused for a long period of time. So, what kind of adjustments will need to be made for single ply roofing in high humidity environments? Well, there are several, including:

  • High performance metal lined vapour control layer to increase the water vapour resistance
  • Using a fully adhered single ply installation method instead of a mechanically fastened system. This is because the mechanical fastenings can rust in high humidity.
  • Changing carbon fixings to stainless steel fixings

Inclusion of air conditioning/ventilation to change the humidity inside the build (Continue reading here to learn more)

Roper Roofing & Solar is a trusted name for commercial roofing installations. We have installed, repaired, and replaced many commercial roofs in your local area. Call us today to get started


795 McIntyre St. Suite 303
Golden, CO 80401
Phone: 720-809-7586

7421 Brecourt Manor Way
Austin TX 78739
Phone: 512-305-3695



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