Short Answer
They can discuss project parameters with the contractor, but limiting necessary structural repairs can create a conflict between budget and proper installation.
Detailed Explanation
Homeowners can discuss budget parameters with the contractor, including setting a cap or allowance for decking replacement. However, if the contractor discovers during tear-off that more decking needs replacement than the cap allows, the homeowner faces a choice: pay for the additional decking or leave deteriorated decking in place under the new roof. Leaving rotten decking under a new roof compromises the entire system — fasteners won't hold, the roof may sag, and the new roof won't perform properly. The better approach is to understand the per-sheet cost before the project, set a reasonable allowance based on the contractor's estimate, and be prepared for the possibility that concealed damage may require additional decking. A responsible contractor communicates findings during the project and gets approval before proceeding with additional work.
Why It Matters
Capping decking replacement to save money can result in a new roof over a compromised deck. Understanding the per-sheet cost and being prepared for concealed damage is the better approach.