Insulated roof for vented attic?
Question: should we have any insulation added when we replace our roof?
We have an vented attic and a hip style roof with gabble vents. Contractor proposes Roof Ridge Exhaust Vent. Our interior was air sealed but our heat pump air handler is in the attic. Renovated last year and ceiling should be adequately (minimally per code) insulated with fiberglass batts. We’re in zone 4a (long island, NY).
Longer context:
We’re planning on having our roof replaced since we’re not sure how old it was when we bought the house (might be < 10 years) but our gutter cleaners noted the plywood (I think) along the edges of the roof were soft and likely needed to be replaced. In all fairness, they’re also roofers so maybe they just wanted business. But we’re also playing on getting solar installed, and I definitely want a new roof before I install solar.
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Replies
It doesn’t make any sense to add exterior insulation or even insulation on the underside of the roof sheathing if you have a vented attic. The outside air will just “bypass” all of the insulation, rendering it useless. If you plan on one day converting the attic to an unconditioned attic then perhaps it might make sense to install the exterior insulation now and convert the attic at a later date.
wag2639,
Are you sure you have a hipped roof? Hipped roofs don't have gable vents.
Your gutter cleaners (roofers) shouldn't be able to see the plywood at the eaves. There should be a drip-edge flashing in the way. If there isn't, there may well be damage to the sheathing. On re-roofs the contract usually includes a contingency assuming some percentage of the roof sheathing will need replacement. Hopefully it's just those sheets at the eaves.
As Matthew said: the only reason to add insulation either above or below the roof is if y0u are considering switching to a conditioned attic.