Guides
Flat roof how-tos that answer the question first
Each guide opens with a short answer, then the details: which roof types it works on, the materials, step-by-step, and when the job belongs to a licensed roofer.
Leaks & repairs
- How to find a leak in a flat roof On a flat roof the drip inside is often nowhere near the hole, because water runs along the deck and through insulation before it shows. Start at the stain, then check the usual suspects on the roof above and upslope: wall and curb flashings, pipe boots, edge metal, seams, drains and low spots where water ponds. If a dry inspection doesn't find it, hose-test one small area at a time, working from the drain up, giving each section at least 10 minutes with a helper watching inside. 8 steps Video
- How to patch a flat roof leak On an asphalt-based flat roof (modified bitumen, built-up or roll roofing), a rubberized wet-patch cement such as Henry 208R can be troweled on even in the rain to stop a leak today. The lasting repair is a fabric-reinforced three-course patch, or on EPDM, TPO and PVC a patch of matching membrane, because asphalt cement damages rubber and PVC and ruins TPO for future welding. If you plan to coat later, Henry says to wait 30 days over its wet patch, and white coatings may need a bleed-blocking primer. 9 steps Video
- How to repair flat roof flashing and seams Most flat-roof leaks start at the edges and joints, not in the middle of the sheet: wall and curb flashings, edge metal, pipe boots, pitch pans, drains and open seams. Small repairs follow one pattern: clean down to sound material, use a sealant and reinforcing fabric (or tape) that match the membrane, carry the repair a few inches past the damage, and re-secure any loose metal. Torch work, heat-welding, drain rings and edge-metal replacement belong to a licensed roofer. 9 steps Video
Coatings
- How to coat a flat roof Coating a flat roof is mostly prep: confirm the roof is dry inside, wash it, make repairs, reinforce seams and flashings with fabric, and prime where the label says, then roll or spray at the manufacturer's spread rate and check thickness with a wet-mil gauge. One gallon spread over 100 sq ft is about 16 wet mils, and the dry film is that times the coating's volume solids. Pick a window with no rain or dew for the label's cure time: often 24 hours or more for acrylic, as little as 15 minutes to a few hours for silicone. 10 steps Video
- Silicone vs acrylic roof coating Choose silicone if any part of your flat roof holds water after rain or you need to coat between afternoon storms: it resists ponding, can go on in one thick coat and is often rain-safe within minutes to a few hours. Choose acrylic if the roof drains well and you want the easiest DIY job, a whiter finish and the freedom to recoat with either chemistry later. The catch most people miss is that once a roof is silicone-coated, only silicone will stick to it. Video
- What coating can go on my flat roof? Start with what's on the roof now. Asphalt roofs (modified bitumen, built-up and roll roofing) take most coatings but need a bleed-blocking primer under white silicone. EPDM rubber takes silicone after an EPDM cleaner and primer but never asphalt products, and TPO and PVC need a single-ply primer and a coating whose label names them. Spray foam takes acrylic, silicone or urethane, and a silicone-coated roof accepts only more silicone. Video
Maintenance & ponding
- Flat roof maintenance checklist: what to check each season Inspect a flat roof at least twice a year, in spring and fall, and after every major storm. In Florida, time those checks around the rainy season (mid-May to mid-October) and hurricane season (June 1 to November 30): clear drains and fix small defects before the rains, and document the roof's condition before a storm. Most of the checklist is looking and cleaning; repairs belong to a licensed roofer. 7 steps Video
- How to fix ponding water on a flat roof Water that is still on a flat roof 48 hours after rain is ponding, and it means the roof isn't draining the way the building code intends. Start by clearing drains, scuppers and gutters; if water still sits, the fix is usually a roofer adding slope (tapered insulation or crickets) or adding drainage. Small spot fixes often run $500–$2,500, while tapered insulation added during a reroof typically adds $2–$5 per sq ft of treated area. 6 steps Video
Storms & hurricanes
Planning, permits & hiring
- Flat roof types explained: what's on your roof and what it costs Most flat and low-slope roofs are one of eight systems: modified bitumen, built-up (tar and gravel), rolled roofing, TPO, PVC, EPDM, spray foam or low-slope metal. You can usually tell them apart by color, seams and surface texture. Installed prices run from about $2–$5.50 per sq ft for rolled roofing to $7–$14 for PVC, and knowing your system decides which patches, coatings and roofers fit it. Video
- Florida flat roof permits and rules: what homeowners should know In Florida, reroofing and most roof repairs need a building permit, pulled by a licensed roofing contractor or by a qualifying owner-builder. Under the "25% rule," repairing 25% or more of a roof section within 12 months can require the whole section to meet current code, but since 2022 roofs built to the 2007 Florida Building Code or later only need the repaired part brought up to code. Miami-Dade and Broward add High-Velocity Hurricane Zone rules, and insurers can't refuse a policy solely because a roof is under 15 years old.
- How to hire a flat roofer you won't regret Before you hire a flat roofer, verify the license (in Florida, on DBPR's website; certified licenses work statewide, registered ones only locally), get a certificate of insurance sent by the roofer's agent, and confirm workers' comp in the state's proof-of-coverage database. Compare at least two itemized written estimates for the same roof system, and make sure the roofer pulls the permit. After storms, walk away from anyone who offers to waive your deductible or handle your insurance claim.