GAF Timberline HDZ Shakewood & SA Mod Bit Flat Roof — Hopkinton, RI

Like most Pinnacle roofing projects, the work was completed in a single day — minimizing disruption for the homeowner.

Pinnacle makes every roof affordable with monthly financing options to make your home project affordable with low monthly payments, including 0% interest for 18 months.

This home in Hopkinton received a dual-system roof replacement — GAF Timberline HDZ shingles in Shakewood on the sloped sections and a SA (self-adhering) modified bitumen rolled asphalt system on the flat roof area. This combination addresses the two distinct roof geometries with the right material for each — architectural shingles where slope allows proper water shedding, and a commercial-grade flat roof membrane where low slope demands a fully adhered, watertight surface.

Scope of Work

Pinnacle’s crew stripped both the sloped and flat roof sections down to the deck, inspected all sheathing, and installed two coordinated systems. On the sloped sections: ice and water shield at eaves and valleys, synthetic underlayment, new drip edge, starter strip, GAF Timberline HDZ shingles in Shakewood, and matching hip and ridge caps. On the flat section: a self-adhering modified bitumen membrane system engineered for zero-slope performance. The transition between the two systems was sealed with proper step flashing and membrane overlap to create a continuous weather barrier across both roof planes.

What We Installed (And Why)

GAF Timberline HDZ is America’s most popular architectural shingle — the #1 selling shingle in North America for over two decades. It features GAF’s LayerLock technology for a strong mechanical bond between shingle layers, delivering 130 MPH wind resistance backed by a WindProven limited wind warranty. Shakewood is a warm, natural wood-tone color that blends brown and amber granules to create the look of aged cedar shake without the maintenance liability.

For the flat roof section, SA modified bitumen is the right choice. Self-adhering mod bit eliminates the need for open-flame torch application — each layer bonds directly to the substrate through an aggressive adhesive backing that creates a monolithic, watertight membrane. The multi-layer system handles ponding water, thermal cycling, and foot traffic better than any shingle product could in a low-slope application. It’s the commercial-grade solution for residential flat roofs.

Project Photo Gallery

The completed dual-system roof — GAF Timberline HDZ Shakewood shingles on the sloped sections with the flat roof membrane visible below.

Transition detail — the connection between the sloped shingle system and flat modified bitumen membrane, sealed with continuous flashing.

Good To Know

Many homes in Rhode Island have a mix of sloped and flat roof sections — and they require different materials. Shingles are designed to shed water on slopes of 4:12 or greater, but they can’t handle the ponding water that occurs on flat or very low-slope surfaces. Modified bitumen is engineered specifically for those conditions — fully adhered, multi-layer, and designed to be watertight even when water sits on the surface for extended periods. Using the right material for each roof geometry isn’t an upgrade — it’s a requirement. One material can’t do both jobs.

Why This Approach Works

A dual-system installation requires careful coordination at the transition points where the sloped shingle roof meets the flat membrane. That transition is where most leaks occur on mixed-geometry roofs, and getting it right means integrating the flashing, underlayment, and membrane overlap into a continuous system with no gaps. Pinnacle’s crew handles both GAF shingle installations and flat roof membrane work, so the entire project is executed by one team with one standard — no subcontracted handoffs, no coordination gaps between trades.

Why Pinnacle

Pinnacle Roofing is a GAF Master Elite contractor — a designation held by only 2% of roofing contractors nationwide — which means access to GAF’s strongest warranty coverage and verified installation standards on every GAF project. Dual-system projects benefit especially from working with a contractor credentialed in both shingle and flat roof installation, since the quality of the transition between systems determines the long-term performance of the entire roof. Whether it’s a mixed-system replacement in Hopkinton or a standard shingle project in Exeter, the installation approach stays the same: do it once, do it right, back it with the best warranty available. With over 100 five-star Google reviews and an A+ BBB rating, our track record speaks for itself.

Hopkinton, RI

Hopkinton’s rural character and wooded lots mean homes often face unique roofing challenges — tree canopy proximity creates moisture and debris buildup, while the town’s exposure to western weather patterns brings heavier snowfall than coastal communities. Many Hopkinton homes also feature mixed roof geometries, with flat-roof additions on otherwise sloped structures. Pinnacle has completed numerous roofing projects throughout Hopkinton and brings both the material expertise and the multi-system capability these properties require. See our Hopkinton roofing page for more on how we serve this community.