Roof decking (also called roof sheathing) is the structural plywood or OSB layer that sits directly under the underlayment and shingles. In Surrey’s high-rainfall environment, decking is the component most vulnerable to long-term moisture damage — and unlike shingles, decking damage is often invisible from outside the home until a re-roof exposes it. This guide covers decking repair costs and what you need to know before your Surrey re-roof.

Roof decking specialist Surrey BC: I-M Roofing Ltd. — 236-838-9577

Roof Decking Repair Cost Surrey BC — 2026

Why Surrey Roofs Have Decking Damage

Decking rot in Surrey homes usually originates from one of three sources:

1. Long-term slow leak at flashings — chimney, valley, or pipe boot flashings that leaked for years without being noticed dry-cycle the deck over time, slowly breaking down the wood fibers
2. Blocked or inadequate attic ventilation — condensation from the warm attic interior accumulates on the cold underside of the deck in Surrey’s winter, gradually soaking the wood from below
3. Re-roofing over existing layers without inspection — a common issue on Surrey homes re-roofed 15–20 years ago without checking the deck; trapped moisture between layers destroys the deck from within

What We Do When We Find Decking Rot

I-M Roofing provides photo documentation of all decking rot found during tear-off. The decking repair cost is quoted separately from the re-roof and documented in writing before work proceeds. Homeowners have the right to see the damage and approve the additional work before we cut new deck material.

We recommend:

• Replace all visibly soft, spongy, or delaminated sheets — not just the visibly blackened ones
• Use CDX plywood (rated for exposure) — OSB is cheaper but less moisture-tolerant for re-roof applications
• Inspect rafter tops for any soft spots before installing new deck

Related

• Roof Replacement Surrey BC
• Re-Roofing vs Full Tear-Off Surrey BC
• Roof Ventilation Surrey BC

Pre-re-roof deck assessment: 236-838-9577