Short answer
Porch roof tied into the house: a self-adhered modified bitumen system (base plus cap) is the usual DIY pick, with flashing up the wall. Detached garage at 2 in 12 or more: mineral surface roll roofing over felt is the budget option. Flat garage roof: EPDM or a low slope self-adhered system. Over heated space in snow country, add an ice barrier at the eaves.
Match the roof to the product
Garage and porch roofs by slope
| Roof | Typical slope | Good choices |
|---|---|---|
| Porch or addition roof tied to the house | Often 1/4 to 3 in 12 | Self-adhered SBS system; EPDM |
| Detached garage, pitched | 2 in 12 and up | Mineral surface roll over felt; shingles at 4 in 12 and up |
| Garage with flat or near flat roof | Under 1 in 12 | EPDM; low slope self-adhered system; TPO by a roofer |
| Carport | Varies | Self-adhered or EPDM if low; mineral roll if 2 in 12 and up |
Slope limits from IRC R905.5, GAF and GAF Liberty. HOA note from Hunker.
Options worth buying
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01Porches
Self-adhered SBS cap and base
Best for: porch and addition roofs, low slope garages
- Install
- peel and roll
- Slope
- low slope rated
- How-to: install peel-and-stick roofing.
-
02Flat garages
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03Budget
Mineral surface roll
Best for: detached garages at 2 in 12 and up
- Coverage
- about 1 square per roll
Where the porch meets the house
Most porch roof leaks start at the wall, not in the field. The roofing should turn up the wall and be covered by flashing that the siding laps over, so water always runs down and out. If that detail means removing siding or working near a second floor window, it may be the part to hire out.
Ice barrier details: ice and water shield. Weighing roll roofing against shingles on a visible roof: rolled roofing vs shingles.
Questions people ask
What is the best roofing for a low slope porch roof?
For a porch at 1/4 to 3 in 12, self-adhered modified bitumen is common because it seals without a torch and has no exposed nails. GAF lists its Liberty system for porches, garages, carports and sheds. EPDM works too. Mineral roll roofing needs at least 1 in 12 by code and often 2 in 12 by the wrapper.
Can I use roll roofing on an attached garage?
Yes, if the slope suits the product and your code and HOA allow it. Over a heated space or one tied into the house roof, follow the ice barrier rules for your area and flash carefully where the garage meets the house wall.
Does a porch roof need ice and water shield?
In areas where your code requires an ice barrier, the requirement applies to the roof edges of the building. Porches over unheated space are less prone to ice dams, but the low slope makes self-adhered underlayment or a self-adhered roof a good idea anyway. Check local code.
Will roll roofing look bad on my house?
It looks plainer than shingles, and Hunker notes many HOAs do not allow it. On a low porch roof that is barely visible it is often fine; on a visible garage roof facing the street, compare with shingles if the slope allows.
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.