Insulation problems

One cold room is rarely an insulation problem across the whole house. Check for a closed or crushed duct, a missing wall cavity fill above a bay window or cantilever, and an uninsulated floor over a garage or porch. Insulating the whole attic will not fix a room that is cold because it has no supply air.

Ice dams are a heat-loss and ventilation problem, not a gutter problem. Warm air escaping into the attic melts snow on the upper roof; the water refreezes at the cold eave. The fix is air sealing the ceiling plane, getting attic insulation up to the recommended level, and keeping soffit-to-ridge ventilation clear. Heated cables treat the symptom. If a contractor quotes cables without discussing air sealing, get another opinion.

High bills with an insulated attic usually means air leakage or compressed, disturbed, or wet insulation. Attic insulation that has been walked on, pushed aside for wiring, or soaked by a roof leak has lost much of its rated value. Look at it. Loose-fill should be even and level with no visible top plates, wiring runs or recessed light housings poking through.

A hot attic in summer is normal. A hot upstairs is not. The usual culprits are ductwork running through the unconditioned attic, insufficient ceiling R-value, and blocked soffit vents where insulation was blown right up against the roof deck. Baffles at the eave are cheap and frequently missing.

How to choose

Look before you buy

Go into the attic with a flashlight. Uneven depth, visible joists, daylight at the eaves, and dark grey staining on the insulation surface all tell you something specific. Photograph it before any contractor visits.

Grey staining means air is moving through

Dirty patches on the top of attic insulation are filtered dust from air leaking up through the ceiling. Those spots are your air sealing map.

Rule out ducts before blaming insulation

A disconnected or leaking duct in an attic or crawl space can cost more than a whole attic's worth of missing R-value, and it is much cheaper to fix.

Treat wet insulation as a roof or plumbing job first

Replacing insulation under an active leak wastes the money twice. Find and fix the water, dry the cavity, then insulate.

Be skeptical of free inspections that always find a total replacement

A legitimate assessment produces photos, depth measurements, and a mixed recommendation. An inspection that concludes "remove everything and spray foam" every time is a sales script.