How Do You Install Roll Roofing?
To install roll roofing, tear the old material off down to a clean deck, replace any soft or rotted decking, and set the drip edge. Roll out the first course along the lowest edge of the roof and work upward, so every course laps over the one below it. Nail the laps, and carry the material up any wall the roof runs into instead of stopping it at the joint.
Installing Roll Roofing
What Slope Does Roll Roofing Need?
Roll roofing is built for low-slope roofs, not steep ones. The generally accepted minimum is 1:12 — one inch of fall for every twelve inches of run. Between 1:12 and 2:12, most manufacturers require double coverage, where each course overlaps the one below it by about 19 inches so the roof is effectively two layers thick everywhere.
Above 4:12, roll roofing is the wrong material; shingles shed better and last far longer. Below 1:12, water sits instead of running off, and no roll product is rated for standing water. A dead-flat roof needs a membrane system: TPO, EPDM, or PVC.
That matters more here than in a dry climate. Our freeze-thaw cycles push water back under any lap that wasn’t sealed properly, and a shallow roof holds snow long enough for ice dams to form at the edge.
Roll Roofing Installation, Step by Step
1. Tear off and inspect the deck
Strip the old roofing completely. Going over failing material traps moisture and hides rot. With the deck exposed, walk it and look for soft spots and daylight around penetrations. Replace anything that flexes underfoot before a roll comes off the truck.
2. Set the drip edge and underlayment
Drip edge goes on the eave first, then the rakes. It gives the roll a clean edge to bond to and keeps runoff from wicking back under the deck. Underlayment adds a second line of defense on a roof this shallow.
3. Roll out the first course at the low edge
Always start at the lowest point and work up. Let the first course hang about a quarter inch past the drip edge. Unroll the material and let it relax flat before fastening anything.
4. Lap, nail, and seal every course
For single coverage, standard practice is a 2-inch side lap and a 6-inch end lap, with nails roughly 3 inches apart through the lap and a bed of roofing cement between the layers. Double-coverage products carry the overlap on the selvage edge instead. Stagger end laps course to course so seams never stack, and keep nails out of the exposed field wherever the product allows.
5. Finish the transitions last
Penetrations, edges, and wall connections come after the field is down. This is the slow part, and the part that decides whether the roof lasts.
Where the Roof Meets a Wall, Run the Roofing Behind the Siding
When a low-slope roof runs into a wall — a back porch, a tied-in garage, an addition — that joint is the weakest point on the roof. The usual approach is to stop the roofing at the wall and cover the joint with flashing.
We do it differently when the wall allows it. We take the siding off, run the roll roofing directly up the wall in one continuous piece, and put the siding back over it. The transition is covered by the same sheet as the roof, so there is no seam at the joint for water to find. Flashing still plays its part, but the waterproofing no longer depends on it alone.
It takes longer. It also removes a failure point instead of sealing over one.
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Peel-and-Stick, Torch-Down, or Nail-Down?
Three fastening methods cover most jobs:
| Method | Best For | How It’s Installed |
|---|---|---|
| Nail-down (mineral-surfaced) | Sheds, garages, detached outbuildings | Roofing nails plus cement at every lap |
| Peel-and-stick (self-adhering) | Occupied homes, porches, additions | Adhesive backing, no open flame or fasteners in the field |
| Torch-down (modified bitumen) | Commercial and larger flat areas | Heat-welded seams, applied by trained crews only |
Peel-and-stick is common on residential work because it seals as it goes and needs no torch near a finished house. Torch-down belongs to trained commercial crews.
Where Roll Roofing Works Best Around Here
Across our service area, roll roofing shows up on the same structures: detached garages, sheds and barns, porch and carport roofs, shallow-pitch additions, and small commercial buildings. It goes down fast, costs less than most alternatives, and holds up well when the laps are done right.
Our crews bring the Amish craftsmanship this region is known for to these jobs, and depending on the service and the situation, installations are backed by our $30,000 guarantee.
FAQ'S
One inch of fall per twelve inches of run, or 1:12. Between 1:12 and 2:12, install it in double coverage so the roof is two layers thick throughout. Anything flatter needs a membrane system instead.
For single coverage, plan on 2-inch side laps and 6-inch end laps, staggered from course to course. Double-coverage products use a wider selvage edge, typically around 19 inches. Confirm the numbers against the product spec sheet.
The material is a finished surface, so manufacturers do not always require it. We put it down anyway. On a shallow roof in a freeze-thaw climate, a second barrier between the deck and the weather is worth the small added cost.
It is possible and usually a bad idea. The old surface is rarely flat enough for the new material to bond evenly, and anything wet underneath stays wet and rots the deck out of sight. A tear-off costs more up front and gives you a roof you can warranty.
A small shed roof is within reach of a confident DIYer. Anything attached to your house is a different job. The laps, the nailing pattern, and the wall details are where roll roofing leaks, and those are the parts that look finished from the ground, whether they were done right or not.
For the low-slope sections — a porch, a garage, a shallow addition — yes, when installed correctly. For the main steep-slope roof, no. Shingles or metal outlast it by decades on that pitch.
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