Flat Roof Repair in Rahway, NJ

Where flat roofs hide on Rahway houses

Even a house with a pitched shingle roof often has a flat section somewhere: the roof over an enclosed porch, a one-story rear addition, a shed dormer, a garage, or the back half of a two-family home. Mixed-use buildings along Main Street and Irving Street often have flat roofs over the whole building. If you own a two-family, our guide for two-family owners covers the flat sections and porch roofs those homes tend to have.

What goes wrong

• Ponding. Water should drain within a day or two. If it sits longer, the roof is too flat in that spot or the drain is blocked.
• Seams. Flat roofs are made of sheets or rolls that overlap. Seams that open up are the most common leak.
• Blisters. Bubbles where moisture or air got trapped under the surface.
• Wall joints. Where a flat porch roof meets the side of the house is a classic leak point, because the flashing has to tuck behind siding or into brick.
• Wear. Older roll roofing and modified bitumen crack and craze with age.

The materials you're likely to find

• EPDM - black rubber sheets. Common on homes, durable, repairable with patches.
• TPO - white membrane with heat-welded seams. Reflects summer heat; popular for newer work.
• Modified bitumen - asphalt-based rolls, often with a granule surface. Common on older porches and additions.
• Roll roofing - the budget option on old porches and sheds. Short-lived.

Repair or replace?

A puncture, a single open seam or one bad flashing detail can usually be repaired. Water that ponds in the same spot every time may need tapered insulation or a better drain. A membrane that's cracked all over, soft underfoot, or covered in old patches is ready for replacement. Because flat roofs are often small, replacing the whole section is sometimes only a modest step up from a big repair.

Help your flat roof last

• Clear drains, scuppers and gutters, especially after the leaves drop
• Keep foot traffic off unless the roof is built as a deck
• Have it looked at after big storms