Shingle Roof Replacement Services

Shingle roof replacement removes an existing asphalt roof covering and installs new roofing materials over a prepared deck. The roofing crew also evaluates components beneath and around the shingles before completing the new roof, addressing the complete roofing assembly rather than only the visible shingle surface. Asphalt shingles generally work on steep slope roofs; NRCA recommends a 4:12 minimum slope, although some manufacturers and building requirements allow installation down to 2:12 when additional application requirements apply.

Widespread cracking, missing shingles, exposed asphalt, repeated leaks, and deterioration across multiple roof planes can indicate the need for replacement. Missing shingles interrupt the overlapping drainage surface, cracked shingles can expose underlying materials to rain, and widespread granule loss can leave the asphalt layer with less surface protection. Wind and storm damage can accelerate all of these problems at once; see the storm damage roof replacement guide for a closer look at that scenario. Roof age alone does not determine replacement. A roofing contractor should evaluate shingle condition, flashing, roof decking, ventilation, previous repairs, and leak history before recommending replacement.

A roof inspection defines the replacement scope before work begins. The contractor examines shingles, valleys, flashing, eaves, penetrations, ridge areas, ventilation openings, and visible decking. Roofers measure roof area in squares, where one roofing square equals 100 square feet of roof surface, so a 25 square roof contains approximately 2,500 square feet of measured roofing area. Roof geometry also affects the project: valleys, dormers, chimneys, skylights, and plumbing vents create additional locations where the roofing crew must cut shingles and integrate flashing. An attic inspection can identify moisture staining, damaged sheathing, blocked ventilation, and previous leak paths that remain hidden from an exterior inspection.

Shingle removal exposes the roof deck and allows direct inspection of concealed conditions. The roofing crew removes old shingles, ridge materials, loose underlayment, and related materials included within the project scope, which can reveal rotten sheathing, old flashing problems, or previous installation defects. NRCA recommends removal of existing roof coverings when multiple roofing layers already cover the deck.

Plywood and oriented strand board commonly form residential roof decks. The roofing crew examines exposed decking for rot, delamination, moisture damage, broken panels, and unsupported sections, since damaged sheathing requires correction before underlayment and shingles cover the roof. A stable roof deck provides the foundation for underlayment, fasteners, flashing, and the finished shingle covering.

Underlayment creates a secondary water shedding layer between the roof deck and asphalt shingles. Eaves, valleys, and roof penetrations receive concentrated water exposure, and cold climate properties can also experience ice dams near roof edges. Flashing directs water around roof transitions and penetrations; new shingles cannot correct damaged or incorrectly installed flashing.

Roofing nails secure shingles to the deck while factory applied sealant strips help adjoining courses resist lifting after bonding. NRCA recommends galvanized steel or equivalent corrosion resistant roofing nails, with manufacturer instructions determining nail quantity, position, and fastening pattern. Overdriven nails can damage the shingle surface, underdriven nails can prevent shingles from lying correctly, and nails positioned outside the designated fastening area can reduce attachment performance. Cold temperatures can also delay factory seal strip bonding, so the roofing contractor should follow manufacturer requirements for cold weather or high wind conditions.

Drip edge protects roof deck edges and directs runoff away from fascia and perimeter materials. The roofing crew integrates drip edge with underlayment and shingles to maintain a continuous drainage path, and starter shingles create the first sealed shingle course along roof edges. Existing drip edge should receive inspection during replacement rather than automatically remaining beneath the new roof.

Shingle replacement provides an opportunity to evaluate attic intake and exhaust ventilation. A balanced system typically introduces air through lower intake vents and releases attic air through upper exhaust vents, and NRCA recommends approximately 50 percent of ventilation area near the ridge for a balanced configuration. A general ventilation guideline uses 1 square foot of net free ventilation area for every 150 square feet of attic floor area, although qualifying assemblies can use different ratios. The contractor should evaluate soffit vents, ridge vents, insulation clearance, and existing exhaust vents before modifying the ventilation configuration.

Consider a 2,200 square foot single story Portland home with approximately 2,700 square feet of measured roof surface. Existing asphalt shingles show widespread cracking, while attic staining identifies previous water entry near a valley. Roof removal exposes six deteriorated OSB panels; the roofing crew replaces the six panels, installs specified underlayment, corrects valley and plumbing vent flashing, and adds new drip edge. The crew then installs architectural asphalt shingles, compatible starter shingles, ridge materials, and the specified ventilation components. The project demonstrates why complete replacement addresses materials beneath the shingles instead of simply covering visible deterioration.

Several factors combine to set the scope of a shingle roof replacement project. Homeowners planning a replacement can review the roof replacement cost guide for additional budgeting information.

Asphalt shingles form one layer of the complete roofing assembly. Roof decking provides structural support, underlayment adds secondary water protection, flashing controls water at transitions, drip edge protects perimeter details, fasteners secure shingles to the deck, and ventilation manages airflow through applicable attic assemblies. NRCA asphalt shingle quality guidance evaluates the substrate, underlayment, drip edge, fasteners, shingles, and flashing as separate installation areas, and a replacement project should correct identified problems within these components before the roofing crew completes the new shingle surface.