Short answer
Prime the clean, dry deck if the maker calls for it, then lay the self-adhered base sheet from the low edge up with its laps running with the water. Lay the cap sheet over it, offsetting its laps from the base sheet laps. Peel the release film a section at a time, keep the sheet straight, and roll every inch of every lap firmly with a hand roller. Work within the maker’s temperature range and finish edges and walls with the specified flashing.
Before you start
Confirm the slope suits the system: GAF documents list its Liberty system for low slope areas from 1/4 or 1/2 in 12 up to 3 in 12 (GAF). Buy the base sheet, cap sheet, primer and flashing from the same system. CertainTeed notes two ply systems may suit small jobs like porches, and three ply for larger roofs (CertainTeed).
What you need
- Self-adhered base sheetFind it
- Self-adhered cap sheet pick a colorFind it
- Asphalt primer if the system calls for itFind it
- Hand roller roll every lapFind it
- Drip edge or edge metalFind it
- Utility knife with hook bladesFind it
- Chalk line and tape measureFind it
- Knee pads most of the job is on your kneesFind it
How to install peel-and-stick roofing, step by step
Prepare a clean, dry deck
Remove the old roofing and fasteners, replace damaged sheathing, and sweep off all dust. Moisture, dust and frost stop the adhesive from bonding.
Prime if required
Roll or brush the specified primer onto the deck and let it dry to the time on the can. Prime only what you will cover that day.
Install edge metal
Fit drip edge or edge metal as the system detail shows. Many systems lap the base sheet over the eave metal.
Dry fit the first base sheet
Starting at the lowest edge, unroll the base sheet along a chalk line and cut it to length. Roll it back toward the middle from both ends.
Peel and stick the base sheet
Peel the release film from one half, unroll that half onto the deck, then do the other half. Press it down with a hand roller, working from the middle out to push out air.
Lap each base sheet
Lay the next sheet up the slope so it laps the one below by the side lap the maker specifies, with end laps staggered. Roll every lap firmly.
Lay the cap sheet
Lay the cap sheet the same way over the base sheet, offsetting its laps from the base sheet laps so seams never stack. Keep granules out of the laps; most cap sheets have a smooth selvage strip for the lap.
Roll the laps again
Go back over every side and end lap with the hand roller. Pressure is what makes the seam. In cool weather, some makers allow a heat gun at laps.
Finish edges, walls and penetrations
Turn the membrane up walls and finish with flashing and counterflashing as the system shows. Seal around vents and pipes with the maker’s flashing pieces or mastic.
Mistakes to avoid
- Dusty or damp deck. The sheet sticks to the dust, not the deck.
- Skipping primer when the system calls for it.
- Laps against the flow of water. Always start low and lap upper sheets over lower ones.
- Not rolling laps. Hand pressure alone leaves channels for water.
- Leaving an underlayment exposed as if it were the roof. Use a cap sheet made for weather.
Choosing products? See the peel-and-stick buying guide.
Questions people ask
Do I need primer for peel-and-stick roofing?
Often, yes. Many self-adhered systems call for an asphalt primer on wood or concrete decks to get full adhesion. Check the system data sheet; GAF describes Liberty as suitable for many primed substrates.
Can I install peel-and-stick roll roofing in cold weather?
Adhesion drops as it gets colder. Each product lists a minimum temperature, and some allow cold weather installs with extra steps such as warming rolls or using a heat gun at laps. Store rolls in a warm place and follow the data sheet.
Do I need a torch?
No. That is the point of self-adhered systems: GAF says Liberty goes down without torches, open flames or hot asphalt. Some makers suggest a heat gun at laps in cool weather.
How do I roll out a sheet straight?
Unroll it in place first, align it to a chalk line, then roll it back up from both ends toward the middle. Peel the film from the middle out a little at a time as you unroll each half. Split release films make this easier.
See peel-and-stick roll roofing on Amazon
Sources
Last reviewed October 12, 2026. Products and listings change; check the data sheet and wrapper before you buy, follow the maker’s instructions, and check your local building code.