Commercial roofing in Medulla, FL

Many flat or low-slope commercial roofs in this part of Polk County are built with a slope of one-fourth unit in 12, which is about 2 percent. A bid should state the slope the new roof will have and how the deck will be made to drain within 48 hours of rain, since that is the code's definition of positive drainage.

Ask whether the work includes secondary overflow drains or scuppers where a parapet could trap water. Ask as well how the drain sizing was set, since the plumbing code uses the 100-year hourly rainfall rate or other approved local data.

• Slope of the new roof stated in writing
• Overflow drains or scuppers addressed where water could be trapped
• Membrane type named with its ASTM standard, such as D6878 for TPO or D4637 for EPDM
• Edge metal tested to the wind test methods listed in the code

Medulla has 18 percent of its housing units built before 1980, and 16 percent built 2010 or later, so the roof stock is mixed. On an older building, the code can bar a recover and require a full tear-off to the deck if the existing roof is water soaked, deteriorated, or already has two or more layers of covering.

Where a roof went up, got fixed or got replaced under the 2007 Florida Building Code or any later edition, you generally need to bring only the repaired section up to the current standard. Under the 25 percent rule, no more than 25 percent of the roof area may be repaired or replaced in a 12-month period without bringing the whole roof system up to code. Keep records of prior work, since that is how you show which standard applied.