Single-ply roofing systems are typically installed one of three ways: fastened mechanically to the roof deck, ballasted with stone or fully adhered with an adhesive. This post looks into the benefits of a mechanically fastened TPO roof. The most important fact is having a good, clean roof substrate, and keeping any loose debris clear of the membrane before installation. Mechanically fastened roofs are by far the most common, dominating around 80% of the market. They can be installed faster and at a lower cost. Builders like them because they can be easily inspected by the manufacturer, who can quickly validate the workmanship by verifying the fastener pattern and their proper installation. On top of most buildings is a metal deck, then a layer of insulation, then the roof. When installing mechanically attached roofs, the TPO membrane roll is laid down and then the screws are driven directly through the insulation boards into the metal deck below. Typically the screws are drilled in at
the edge of the membrane roll then covered with the edge of the next sheet as the rolls are successively put down. A watertight seal is then created by heat-welding the membranes together with a hot-air gun. This seals any gaps and creates a single, flat, waterproof surface. There are many benefits to a mechanically fastened TPO roof, which include:
- Obtainable with single ply systems of any kind – Half sheets are only required with the mechanically attached systems, T-joints are required on all 60 and 80 mil TPO and only 80 mil on the PVC. If the roof you are working on backs up or butts into a higher building, you don’t need half sheets at that particular wall.
- Low material cost– There is virtually no waste as all the discarded sheet goods can be utilized on the mechanically attached roofing system. The bonding adhesives in the field areas can be eliminated from use. The lightest weight of any installed thermoplastic system, the mechanically fastened system has a reflectivity of white sheet vs. rock or paver ballasted systems. Minimal installation equipment is needed for the attachment of the mechanical systems.
- Fast installation– a smaller crew is possible, as this type of roof is not as labor intensive.
- Membrane Attachment to Structural Desking – A mechanically attached roof system is fastened directly to the structural decking. This means that, in order for the roof system to become de-attached, the fasteners need to pull out of the structural decking. With a fully adhered system, the membrane is only attached to the insulation, so if the insulation facer peels off or becomes delaminated, the membrane sheet can blow off. With a ballasted roof system, If the stone shifts or gets blown off the roof, the roofs attachment, including the insulation, becomes much weaker.
Other benefits include:
- Rarely flops over time
- No foul smells when installing
- Ease of Factory Mutual (FM) compliance
- Ability to improve wind ratings- High wind uplift performance
- Lightweight ?Adaptable to unusual roof configurations
- Membrane securement directly to structural decking
Ultimately, a professional commercial roofing company should make a professional and experienced recommendation on the best type of roofing for your building.