Vented roof / attic assembly

Passive

Air enters low at the soffits and leaves high at the ridge, carrying away heat that builds in the roof space and the moisture that would otherwise condense there. Mixing vent types defeats it: gable vents alongside a ridge vent short-circuit the soffits and the airflow stops doing its job.

One of 7 ways to meet Solar gain avoidance / shading (summer). Build 3/7, Upkeep 3/7, Efficiency not rated. Cost, carbon and footprint below are rated against those 7, not in absolute terms.

Cost: Low
Upkeep: Occasional
Skill to build: Intermediate
Lifespan: That of the roof; the vents themselves need keeping clear of nests, leaves and blown insulation or the path closes
Embodied carbon: Low
Space / material use: Low
Output timing: Continuous process
Skill to repair: Basic

What your site needs

A roof built with a ventilable space, soffits that can take an inlet, and a ridge or upper outlet. The source recommends the opposite, an unvented assembly, where wind-driven rain or wildfire embers are a real risk, since the same openings let those in.

Inputs

none

Outputs

none

Ranking in its sub-function out of 7 alternatives

Every option in this sub-function, with the value on each axis and a note on what drives it (this solution highlighted):

Solution	Build skill	Upkeep burden	Efficiency
Fixed horizontal overhangs (south)	None	0	N/A
Adjustable brise-soleil / shutters (east-west)	Basic	4	N/A
Deciduous vegetation shading	Basic	3	N/A
DIY shade-sail window screen	Basic	2	N/A
Cool (high-reflectance) roof surface	Specialist	0	N/A
Attic radiant barrier	Basic	1	N/A
Vented roof / attic assembly	Intermediate	2	N/A

Build skill and upkeep burden are proxies (lower burden = simpler to maintain); the efficiency column is this sub-function’s ranking, 1 = best. “N/A” where an axis isn’t rated here.

Sources

Building America Solution Center, "Roof Vents" (PNNL / US DOE): "lower soffit vents are intended to supply air to the attic space and the upper roof/attic vents are intended to exhaust air from the attic space"

Tutorials

No build tutorial recorded yet.

What this page does not tell you

No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.