When temperatures dip and the leaves begin to change color, commercial flat-roofed property managers and building owners might find themselves wondering if a flat roof can be replaced in the winter.
The answer, like most things in life, isn’t straightforward. Let’s talk about some of the considerations and nuances so you can plan ahead.
What’s Involved
First, I’ll clarify what I mean by “replacing a flat roof”.
In our context, I am referring to a commercial, single-ply membrane (TPO, PVC, EPDM) flat roof. Replacing one of those involves:
- removing the existing roof down to the structural decking;
- inspecting the deck and replacing worn or damaged parts, as needed;
- layering on new insulation and a vapor barrier;
- installing a new roof membrane, flashing, and edging, and
- sealing the seams.
If you are just adding another roof layer over top of an existing one, that is not a roof replacement. It is a flat roof resurface, restoration, or recover and an option for healthy single-layer flat roofs only.
Can The Work Be Done in Winter
In our market (Southeastern Pennsylvania), a commercial flat roof can be replaced all year long and, to my knowledge, most flat roofing contractors work throughout the year. That said, when installing any roofing material in the winter, it is important to plan around forecast and actual temperatures, ice, and snowfall.
Temperature Sensitivity
Flat roofing material temperature sensitivity varies from one roofing material to another. Metal roofing, for example, is less sensitive to variations in temperature than a single-ply membrane rooftop. Some singly-ply membranes (PVC and TPO) get very stiff at low temperatures and are hard to work with, especially when installed around curbs and other roof details.
Then you have to consider how the membrane is going to be adhered to the roof structure.
If you are installing a fully adhered roof membrane, temperature will impact the process of attaching the membrane to the roof insulation and deck. Fully adhered means the roof membrane is glued down to the insulation. This is typically done with a solvent-based adhesive.
New water-based adhesives are becoming increasingly popular, but they are also more temperature-sensitive. Solvent-based adhesives can be used in temperatures from 40 degrees Fahrenheit (F) and up whereas water-based ones can only be used in temperatures 50 degrees F and higher. Neither can be exposed to freezing temps within 12 hours of applying.
Temperature also affects the storage of adhesive. Adhesive storage requires temperatures between 60 and 80 degrees F. During winter, this means adhesive must be stored inside the building and loaded onto the roof daily.
Even when you meet temperature requirements during the application, the glue takes longer to flash off in winter. That means your productivity rate slows as your crew waits for the glue to be ready.
Mechanical attachment is a better option in the wintertime. This is when plates and screws are used to attach the roof to the structural deck. A steel plate and screw are not temperature sensitive.
Lastly, temperature affects crew productivity. People are less efficient when working on a roof in colder conditions. All our contracts stipulate the temperature should be above 20 degrees F and increasing before the crew can begin.
Ice and Snow
Ice and snow are considerations when replacing a flat roof in winter. In Southeastern PA, we don’t generally get a lot of snow and ice. When working on a roof with snow or ice, we power broom it away in the area we plan to work on for the day rather than clear the entire roof. I believe this is what most commercial roofing contractors do across the country, regardless of how much is on the roof.
Night sealing the roof is critically important in wintertime. Night sealing involves sealing the leading edge of the new roof to the old roof to prevent water infiltration on large commercial projects that can’t be completed in one day. Wintertime is especially hazardous because melting snow and ice can easily find a pinhole in the roof, even more so than in heavy rains. So, if there’s precipitation on the roof, especially if it’s getting towards Spring and it’s starting to melt, you want to be extra diligent on the night sealing.
Conclusion
In conclusion, yes, you can replace a commercial flat roof in the winter, but there are extra planning considerations including the type of roofing materials used, temperatures, ice, and snowfall. These all have the potential to impact the schedule and crew productivity.
As always, feel free to reach out to one of us if you have any questions or need assistance.
Add your first comment to this post