“[With] fully adhered [systems], you’re totally reliant on the substrate that you’re adhering the membrane to [in order to] hold the roof on. You’re not using fasteners and plates or bars, you’re just gluing the membrane to the substrate – sometimes, that’s right to the deck material, insulation, and in some cases, an existing membrane. While mechanical fastening involves the expense of increased labor time and materials, fully adhered systems can be quite economical – especially when considering self-adhered products like peel-and-stick TPO.

Again, it’s important to think about the roof deck and its role in this decision. “We don’t recommend mechanically attaching a roof – any kind of roof – to a concrete deck. We just don’t think it is the right thing to do (hammer-drilling holes in a concrete deck to attach the roof). Now, we do recommend adhering single-plies to a concrete deck with an adhesive. We think that’s an appropriate solution. While it’s not uncommon to mechanically fasten a roof to a concrete deck, fully adhered systems have been found to provide excellent wind uplift resistance in these applications. Additionally, various peel-and-stick TPO membranes must have a suitable substrate in order to bond properly.

Using fasteners to secure the roof is one single-ply roofing installation method. When considering the fastening method most appropriate for your application, it’s important to make a selection based upon many factors, including the type of roof deck (wood, metal, concrete, etc.) on your building. “Mechanically fastened single-plies will work on just about any type of roof deck. Where you have to be careful is when you get into some of the very lightweight decks, such as the cementitious wood fiber and gypsum decks. Lightweight insulating concrete you have to be careful with, because you’re relying on that material to hold the roof down. In many cases, manufacturers will recommend fastening through the insulating concrete into the structural deck. Some of these applications may require narrower sheets and more fasteners to ensure that there isn’t a greater likelihood of fastener pull-out (referred to as pull-out value).

Careful consideration should be taken so that the proper number of fasteners is used. Installing a roof with an insufficient number of fasteners can increase the chances of blow-off. When one fastener pulls out, its load is transferred to surrounding fasteners, increasing the chances of their pull-out as well.

If the facility is located in an area prone to high winds, the means for attaching your single-ply roof is especially important. “If you’re in a wind zone or a place where you’re exposed to high wind uplift conditions