A conservative fastening schedule is normally advised. Chemically adhered membranes use adhesives to hold the membranes to the roof substrate. The time and labor to apply the adhesive and smooth the sheets in place adds to the cost of the job, but the bond achieves a roof that is highly resistant to wind, water, and dimensional changes. Ballasted roofs weight the membrane with gravel or pavers. This is the least expensive application, but there are drawbacks.
Wind can blow the ballast off causing damage to the membrane or other surfaces.
TPO combines synthetic rubber with polymers, such as olefins, making a more stable formulation. This advantage, combined with the membrane's low cost, makes it attractive. Disadvantages include a lack of testing and a limited number of installations, making it difficult to accurately assess the performance of the membranes. Roof membranes are made of several different chemical compounds. You may apply for credits either by downloading the form and faxing or mailing it, or by completing the electronic version and sending it via the Internet.