Guides · Updated October 11, 2026
Ridge vent versus hip caps
The cap and the vent are two products on the same line. The vent is a slot, or a roll, along the peak that lets hot air out of a vented attic. The caps fold over that slot and shed rain to both sides. Install the vent first. Nail the caps over it, in the zone the bundle shows.
Vent the ridge only
On a gable, the vent length matches the ridge. On a hip, the vent matches the ridge and stops there. The four hips get caps and no vent. A 40 by 30 ft hip at 6:12 is about 100 ft of cap and 10 ft of vent. The buying list orders that vent in 20 ft rolls, so 10 ft is one roll and a 40 ft ridge is two. See that split in the estimator.
If the hips meet at a peak, the ridge length is zero. There is no ridge vent run. The attic needs another exhaust, usually a roof pot or a gable vent, sized by someone who is looking at the intake.
The slot has to breathe in both directions
Cut the ridge slot to the width the shingle maker specifies, and stop about 6 inches short of each end so wind-driven rain has a dam. The vent only works if fresh air can enter, almost always at the soffits. A ridge slot with blocked soffits moves air in a circle. This estimator gives the length of ridge to vent. It does not size the intake.
Shed roofs
A shed has one high edge and no ridge. Cap that high edge. Do not add a ridge vent. Exhaust is a gable, a soffit, or a high-wall vent. A 50 × 24 ft shed shows cap footage and no vent.
Wings and valleys
A gable wing has its own ridge, and that ridge can be vented if the wing has an attic and open soffits. The valley where the wing meets the main roof is not a vent and not a cap line. Draw mode adds the wing ridge to both the cap total and the vent total, and it leaves the valleys out.