A short ridge can constrain the available exhaust area; roof shape must be considered alongside attic floor area. Have the roofer identify compatible exhaust options and show the intake and exhaust calculation.
Begin with the actual roof shape
A hip roof can look spacious while offering relatively little ridge for a proposed product. Ask the contractor to draw the roof planes, ridges and attic boundaries before selecting vents. The conversation should distinguish available installation locations from the attic area being served. A product that worked on a nearby gable roof is not automatically a complete design for a different roof geometry.
Compare compatible layouts
Request a proposal that names the intake and exhaust products and explains where each will be installed. If different options are offered, compare the full arrangement, including the treatment of existing openings and any roof-covering details affected. Ask whether product instructions, project requirements or access limitations rule out particular locations. Keep the explanation with the estimate so a later substitution can be reviewed against the same assumptions.
Review substitutions before installation
If a selected vent cannot be installed where expected, ask for an updated sketch rather than an undocumented field substitution. The revised plan should show which attic space remains served and whether another trade is involved. Completion photographs can confirm the chosen locations without requiring an owner to climb onto the roof. Retain the final model numbers, because future replacement parts and service discussions should begin with what was actually installed.
For an illustrative bid comparison, one contractor may propose keeping existing exhaust openings while another proposes replacing the arrangement. Ask both to show the roof shape they used and the attic zones covered. Without that shared information, comparing only the vent count or installation price does not reveal whether the proposals are addressing the same scope for the same space.
For related project preparation, see roof ventilation changes during replacement and roof replacement sequencing with attic insulation work. Bring the relevant photographs and existing proposal to Perkins when discussing the roof-specific scope.
Technical references: GAF: ventilation by roof style; GAF: attic ventilation products. These references provide background; the selected assembly and applicable project requirements determine the installation detail.