An annual inspection catches most of them while they're still manageable.
01Structural
Roof deck condition
From inside the attic with a flashlight, look at the underside of the roof sheathing. Dark staining, soft spots, or daylight visible through the deck are signs of water infiltration that need immediate attention. The attic catches roof leaks before the interior does — catching them here is significantly less expensive than catching them at the ceiling below.
Rafter and truss condition
Look for cracked or split rafters, any visible sagging in the roof line from below, or signs of previous amateur repairs — splice plates, sistered rafters with questionable fastening. A structural engineer evaluation is warranted for anything that looks like it was improvised.
Attic floor
If the attic is not finished or regularly accessed, the "floor" is typically insulation laid between ceiling joists. The joists themselves are the structural element — stepping between them means going through the ceiling below. Lay plywood decking over joists in any area you access regularly.
02Moisture and Ventilation
Condensation on sheathing
In cold climates, condensation on the underside of the roof sheathing during winter indicates inadequate attic ventilation or air sealing at the ceiling below. Persistent condensation leads to mold and rot in the sheathing. The fix is either improving attic ventilation or reducing air infiltration from the living space below — both are professional evaluations.
Vent blockage
Soffit vents and ridge vents should be clear and unobstructed. Insulation pushed against soffit vents is the most common blockage — install baffle channels to maintain an air path. A blocked vent system creates heat buildup in summer and moisture accumulation in winter.
Plumbing and exhaust duct terminations
Every bath exhaust fan, kitchen range hood duct, and dryer vent that routes through the attic should terminate at an exterior vent cap, not into the attic itself. A bath fan venting directly into the attic space dumps moisture into the insulation with every shower. This is more common than it should be.
03Electrical
Knob and tube wiring
Homes built before approximately 1940 may have knob-and-tube wiring in the attic. This wiring type is not rated for contact with insulation — insulation packed around K&T wiring creates a heat-buildup fire hazard. If you see ceramic knob insulators and cloth-wrapped conductors, have an electrician assess before adding or disturbing insulation.
Junction boxes
Every electrical junction in the attic should be in an accessible, covered junction box — not wrapped in electrical tape and stuffed into the insulation. An open splice in insulation is a fire hazard and a code violation. If you see uncovered splices, they need to be boxed.
Recessed light fixtures
Older recessed lights (IC-rated or not) that are not rated for insulation contact should have a 3-inch clearance from any insulation maintained around them. Check the fixture housing for an IC or ICAT rating label. If not rated for contact and insulation is packed against it, the heat buildup is a fire risk.
04Pests
Pest evidence
Rodent droppings, chewed insulation or wiring, or nesting material are all indicators of active or recent pest infiltration. Entry points — typically at the roofline, soffit gaps, or where pipes and wires penetrate the exterior — should be sealed with metal mesh or foam rated for pest exclusion. A pest control company can assess and treat; an attic with active rodents also has chewed wiring until proven otherwise.
Wasps and bees
Active wasp or bee nests in the attic should be addressed before the season's population peaks. A nest removed in spring is a one-morning project. A nest left until fall is a significantly larger problem.
Annually, ideally in late spring before heat makes the attic inaccessible and before the pest season peaks. After any significant storm. After adding or disturbing insulation.
Ray Torres is a home safety writer based in Phoenix, Arizona. He writes about the slow, quiet hazards in residential buildings — the ones that have been sitting slightly wrong for long enough that nobody notices them anymore.