When it comes to roofing, Florida has some unique concerns. Nowhere else in the United States has tougher building codes specific to roofing. A lot of this stems from the epic storms that this state sees. Hurricanes and windblown debris can do a lot of damage, which means the state regulates roofing tightly to help keep damage to a minimum. In other words, if you live in Florida, you need a storm proof roof.
To meet codes in Florida, there are several options for underlayment: Peel and stick membranes adhered directly to sheathing, peel and stick adhered to fastened felt underlayment, ASTM #30 felt or approved synthetic underlayment using 4-inch wide peel and stick tape over all seams, or a fastened underlayment covered in a hot-mop cap sheet.
What this means is that peel and stick underlayment and hot mop underlayment are the two biggest choices for Floridians. Which is better? Let’s find out!
What is Hot Mop?
Hot mop is a complex underlayment style which requires a base sheet—usually asphalt felt—over the roof deck. Then a layer of hot asphalt is spread over this base sheet, applied with a specialized mop to help seal the base sheet of underlayment. Over this, roofers install a felt or modified bitumen cap sheet to give the roof a double layer of wind resistant and watertight underlayment. Once finished, hot mop can be nailed to further secure it, or another layer of synthetic underlayment can be placed over top.
This method is sometimes also referred to as “torch down” or “torch applied” when roofers use a flame torch to heat bitumen while they layer it onto the roof. Heating the material with a torch helps it to melt and stick tightly to the base sheet.
Hot Mop vs. Peel and Stick
Both of these methods will work to satisfy Florida building codes, and both will offer an underlayment system that features high wind resistance and water resistance—which is crucial in hurricane prone areas. But does one come out on top over the other?
Hot mop used to be the standard, but these days, peel and stick underlayment is edging hot mop out and for a variety of reasons.
- Because it requires several layers and hot asphalt, hot mop is a much more labor intensive process than peel and stick underlayment—and it can be more costly, too.
- Roofers find the hot mop installation process more dangerous on account of the hot asphalt and the extra loads that need to be carried up and down ladders.
- Peel and stick underlayment features a longer life span than hot mop, particularly in hot areas like Florida, where heat can degrade asphalt more rapidly.
- Peel and stick underlayment also has the advantage in that it can be left exposed for long durations, which is handy in the aftermath of storm damage when roofers may not be able to make roof repairs quickly due to high demand for repairs throughout the neighborhood. Hot mop, on the other hand, is weaker against UV exposure and should be covered as soon as possible.
When it comes right down to it, peel and stick underlayment is the more modern and more practical choice for storm proofing a roof and for meeting building codes in a state with tough codes like Florida. Not only will it make the rooftop more durable, but it’s much easier to install and less expensive, too.