What is the most durable material for a flat porch roof?

Twenty-ounce copper in a flat-lock or batten seam system, with soldered joints. Service life of 50 to 75 years. For a porch roof that is visible and adjacent to copper gutters and flashings, copper is the correct material and the correct long-term investment.

Is EPDM rubber roofing appropriate for a traditional New England house?

Yes, on concealed flat sections where durability and practicality are the specifications. EPDM does not look like a traditional material, but it is hidden from view on the typical ell or dormer flat. It is not appropriate where the flat section is visible.

How do I ensure my flat roof drains properly?

Tapered insulation — polyisocyanurate insulation boards cut to slope from 1/4" per foot minimum — beneath the roofing membrane creates positive drainage to internal drains or roof edges. A flat roof without positive drainage will always pond, and ponding water accelerates membrane failure.

Flat Roof Materials — Built-Up and EPDM — Old Canaan Building Materials

Flat and low-slope roofs appear on traditional New England buildings in specific locations: the porch roof, the bay window top, the low-slope section between a dormer and the main roof, the flat roof over an ell or addition. These are not glamorous roofing situations. They are hidden or partly hidden, utilitarian, and consequential when they fail. The material choice here is determined by durability and detail, not appearance.

The Character

A flat roof that performs correctly is invisible. It is hidden behind a parapet or at a level not seen from the ground. The material choice does not affect the building's appearance — it affects how long the roof performs and what maintenance it requires.

What It Is

Three materials are correct for flat and low-slope roofing on traditional New England buildings. Copper: 20-ounce copper in a batten seam or flat-lock system, soldered joints, 50 to 75 year life, correct for high-quality residential work and for visible low-slope sections adjacent to copper flashings and gutters. Built-up roofing (BUR): multiple layers of felt and hot asphalt, gravel surfaced, 20 to 30 year life, the traditional material for flat commercial and institutional roofing. EPDM: synthetic rubber membrane, 20 to 30 year life, the most common contemporary flat roof material for residential work, correct where copper is not in the budget.

How It Behaves

Copper flat roofing is the most durable option and is correct where the flat section is visible or adjacent to other copper work. EPDM is the most practical option for concealed flat sections — it is durable, can be repaired in place, and does not require the sheet metal expertise that copper demands. Built-up roofing is correct on larger low-slope sections where the aggregate ballast is appropriate.

Why It's Right

The material should be chosen based on the location, visibility, and budget. Copper on a visible porch roof adjacent to copper gutters and flashing. EPDM on a concealed ell roof or dormer flat. Built-up roofing on a parapet-enclosed flat roof. The choice is practical, not aesthetic.

How To Get It

Copper flat roofing through a sheet metal contractor with flat copper roofing experience. EPDM through a licensed roofing contractor — specify 60-mil EPDM, fully adhered, with tapered insulation for positive drainage.

The Old Canaan Standard

Copper batten seam or flat-lock for visible low-slope sections adjacent to other copper work. Sixty-mil fully adhered EPDM for concealed flat sections on residential buildings. Built-up roofing for larger flat sections with aggregate ballast. Positive drainage is the specification for all flat roofing — no ponding water on any flat roof surface.

Something missing from the archive?

Suggest a material →

Flat Roof Materials — Built-Up and EPDM

Suggest a material.