Attic insulation inspection

Light it from the side, not from above

A beam raked low across the surface shows drifts, thin spots and the joist tops that a light shining straight down flattens out completely.

An attic is a confined space with fibrous dust, a ceiling you can put a foot through, and in summer a temperature that shortens how long you can think clearly. The gear is not ceremonial.

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• Fitted respirator, not a dust mask

  Look for P100 or N95 rated, with a seal that fits your face. A loose surgical-style mask is not this.

  Loose fiber and settled dust go airborne the moment you move around up there.

  Skip it if Never. This is the item that has no version of the job without it.

• Sealed eye protection

  Look for Goggles that seal against the face rather than open safety glasses.

  Fiber falls, and it falls at eye level when you are working under a roof deck.

  Skip it if Never, for the same reason.

• Gloves and long sleeves

  Look for Anything that covers skin. Coated palms beat bare knit for handling batts and hardware cloth.

  Fiberglass itches for days and washing does not fully clear it from clothing.

  Skip it if You are only opening the hatch to look and measure.

• Boards to kneel on

  Look for Two lengths of rigid board or plywood you can move ahead of yourself.

  You step only on framing. Boards spread your weight and give you somewhere to put a knee.

  Skip it if The attic already has a walkable deck across the whole area you are working in.

• Disposable coveralls

  Look for A hooded suit rated for particulates. The DuPont Tyvek 400 style is the common one, and it comes in sizes, so buy yours rather than the first size listed.

  Fiberglass in clothing survives a wash and keeps itching. A suit you throw away at the hatch ends the problem at the hatch.

  Skip it if You are working in cellulose rather than fiberglass and do not mind laundering what you wore, or the job is a ten-minute look with a torch.

• Knee pads

  Look for Strap-on pads with a hard cap, not the soft gardening kind.

  The whole job happens kneeling on framing. A joist edge is an inch and a half of wood and your knee finds it within a minute.

  Skip it if Your boards are wide enough to kneel on flat, which is most of the point of them.

• Headlamp

  Look for Hands-free. Any output; attics are small spaces.

  Both hands are busy, and a torch in your teeth points at the wrong thing.

  Skip it if You already own one.

• A fitted respirator, not a dust mask. Both fiberglass and cellulose are respiratory irritants in a hot, confined space, and disturbing settled loose fill puts a lot of it in the air. Add sealed eye protection, gloves and long sleeves.
• A torch or headlamp, a rigid ruler or a steel tape, and a phone camera. Photograph everything you are unsure about from the hatch rather than crawling back later to look again.
• Two boards or a kneeling pad. You step on the framing only, never on the material between the joists, because that is drywall underneath and it will not hold you. Loose fill hides the framing entirely, so probe with a foot before committing weight.
• Someone who knows you are up there. In summer, go early. A dark roof deck turns an attic into an oven by mid morning and heat is the most common reason a survey ends badly.

Where the rules sit: the federal respiratory-protection standard administered by OSHA binds an employer with respect to its crew. A homeowner in their own attic is outside it, which means nobody is going to require any of the above, and it is entirely your call.

When not to enter at all

Four findings mean the survey ends at the hatch.

• Loose gray-brown pebbly granules. That can be vermiculite, which should be assumed to contain asbestos and left undisturbed. Close the hatch. The vermiculite page explains why leaving it alone is usually the correct action, and it carries no quote form for that reason.
• Heavy droppings or nesting. Do not sweep, shake out or vacuum dry droppings. CDC guidance on cleaning up after rodents is to wet the area down first, because the hazard is what goes airborne. Rodent contamination covers the sequence.
• Widespread visible mold. A small patch on sheathing is information. A floor of it is a reason to look from the hatch and no further, particularly if anyone in the house is asthmatic or immunocompromised. See mold in attic insulation.
• Knob-and-tube or damaged wiring, or a roof deck that sags underfoot. Both are somebody else's trade and both are reasons not to add your weight to the problem.

Hold the light low, not high

A beam raked almost flat across the surface throws shadows into every hollow and over every joist. Pointed straight down, the same attic looks evenly covered.

Six checks, and the order matters because the first one that fails ends the rest. Take notes as you go. A survey you have to repeat because you cannot remember the third reading is not a survey.

1. Measure the depth, in several places, away from the hatch

Push a rigid ruler straight down through the material until it stops on the drywall, and read it at the surface without compressing anything. Do that in at least five places spread across the floor: near the middle, in two opposite corners, and at two points along the outside walls where insulation is thinnest.

Plan from the typical reading, not the deepest one. The material near the hatch is the most disturbed and often the deepest, because everyone who has ever been up there has pushed it around. Heat leaves through the thin part of the ceiling, so the number that describes your attic is the one most of the readings cluster around. The thin spots are a separate finding: a patch measuring far below the rest is a levelling job, not a reason to lower the number you plan against. This is the protocol the rest of the site works from, so the depth checker, the add-over guide and the remove-or-add-over test all read a measurement the same way.

Depth converts to R-value by material, and only approximately. The depth checker does the conversion and compares it with the level recommended for your ZIP. One caveat that applies to every loose-fill conversion, including that one: settled density rises as installed thickness rises, so loose-fill R-value does not scale strictly with depth, and a depth reading is an estimate of R rather than a measurement of it.

2. Identify what is up there

You need this to convert depth into R at all, and it changes what happens next. The R per inch figures below are the aged, settled ranges this site carries, not label values for new material.

The last row is the one that catches people out. A radiant barrier reflects radiant heat rather than resisting conduction, so it has no useful R-value per inch and cannot be counted toward an R-value target. It is measured differently from bulk insulation and the two do not add together. If your attic has foil under the rafters and four inches on the floor, you have four inches on the floor. The radiant barrier page covers how it is measured and where it does real work.

3. The joist sight test, priced properly

Before the ruler comes out you already have a rough answer from whether the tops of the ceiling joists are visible. Ceiling joists are dressed under the American Softwood Lumber Standard PS 20 to 5.5 inches for a 2x6, 7.25 inches for a 2x8, 9.25 inches for a 2x10, so material level with the joist tops is material at one of those three depths. What that is worth depends entirely on which material it is, which is why "you can see the joists, therefore you are short" is only usually true.

These are conversions from aged R-per-inch ranges, so they estimate R rather than measure it. Loose fill in particular does not scale cleanly with depth: settled density rises with installed thickness, so a deeper pile returns less R per inch than a shallow one. Treat the figures as a bracket, and the bag coverage chart for the specific product as the authority.

ENERGY STAR recommends a total of R-30 in zone 1 and R-60 in zones 4 through 8 for an attic with no existing insulation. So the deepest common joist filled flush with cellulose is a pass in the warmest zone and a long way short in the coldest, while the same depth in blown fiberglass does not clear anything. Name the material before you draw the conclusion. The R-value targets page has the full table by zone.

4. Moisture staining and daylight

Point the torch at the underside of the roof sheathing and work along it. You are looking for dark rings or streaks, black staining at the ridge, and rusted or wet nail points coming through the deck, which are the cheapest early sign that warm moist air is condensing up there. Then look down: matted or flattened material, a patch darker than everything around it, or damp on the top face of the ceiling drywall.

Distinguish two sources, because the fix is different. A roof leak stains a path from a point above, is worst after rain, and often shows daylight. Condensation is diffuse, worst in winter, and concentrates over bathrooms, the kitchen and the attic hatch. A bath fan ducted into the attic rather than through the roof or wall produces a very local version of the second and is common enough to be worth a deliberate look.

Daylight is not automatically bad. You should see it at the soffit vents, and at a ridge vent. Daylight in the middle of a rafter bay, around a flue, or at a flashing is a roof finding, and it outranks anything on this page.

5. The eaves, which is where most of the failures hide

Crawl or look toward the outside walls and check whether loose fill has drifted or been blown into the eaves and packed the soffit solid. This is the single most common defect in an otherwise reasonable attic, it is invisible from the hatch, and it is the reason a well-insulated attic ends up with a damp deck.

One number is worth carrying up the ladder with you. The Model International Residential Code, Section R806 (roof ventilation), 2021 edition calls for at least 1 inch of open air space between the insulation and the roof sheathing wherever an eave vent is fitted. That is exactly the gap a baffle exists to hold, and exactly what a packed eave destroys. It is also the only venting number you can actually see on a survey. How much total vent area the attic needs is math on the floor area, not something visible from the hatch.

These come from the model International Residential Code. Your state, and often your city, decides which edition applies where you live and whether it was changed. Your local building department is the only authority on that. And these rules cover new building and permitted work, not a top-up you choose to do on an attic you already have.

So what you are recording is simple: at each soffit bay, is there a baffle, and is there a clear channel above it? A vent with insulation packed against it contributes nothing, however many of them the house has. The baffles page covers fitting them, and the ventilation section works out how much net free area an attic of a given size needs, at both ratios.

6. The hatch, and the signs of pests

The hatch is a hole in the middle of the ceiling plane and it is the fastest thing on this list to fix. Note whether it is weatherstripped, whether anything is insulating its back, and whether the material around it has simply been heaped up to the edge of the opening.

For pests, look for five things. Droppings along the joists and against the outside walls. Tunnels and runs through the loose fill, which look like a network of channels rather than random mess. Nesting material gathered in corners. Chewed wire insulation. And a smell that comes back every time the attic heats up. Then look for how they got in. Gaps at the soffit and fascia. Around vent openings. And where the roofline meets a lower roof. Take the fouled material out without closing the entry points and you buy the same job twice.

Boxes on boards are a thin spot you cannot see

Compressed insulation loses R-value roughly in proportion to how far it is squashed. A decked storage area reads as covered from the hatch and performs like a hole.

Work through your notes against this. The verdict column is what to do next, not what to buy.

Two of those rows point to longer pages. Remove or add over works through the contamination and damage decision in steps. Insulating over existing insulation covers the facing rule, and what a second layer can and cannot fix.

Everything above is observation. It establishes what is on the ceiling and what condition it is in. What it cannot do is measure the two quantities that most often decide whether the house performs, because both need instruments and neither shows up on a ruler.

• A blower door test. Your ruler measures the conduction term. The blower door measures the air-leakage term, which your survey cannot reach at all and which is frequently the larger of the two. That is the whole reason to buy one on top of the survey you have just done. Air sealing covers how the test works and what the number means.
• Thermal imaging. An infrared camera reads surface temperature. So when there is a temperature difference across the ceiling, it shows what the flat surface of loose fill hides. Voids. Gaps at the eaves. Edges scoured by wind. Missing sections behind knee walls. And air bypasses at the tops of walls and in chases. Run it with the blower door pulling the house down in pressure and it also shows air moving where it should not. What it cannot do is see through the material, or give you an R-value.
• Duct leakage testing. Where supply and return ducts run through the attic, their losses are outside the ceiling plane entirely, so no depth on the floor addresses them. A pressurized duct test measures the leakage directly, and it routinely reorders the priority list.
• A written report. This is the underrated part. A written scope, in priority order, is what lets three contractors bid on one job instead of three different guesses. It turns "add insulation" into a spec: a target R-value, an air sealing list and a note on ventilation.

Who does them: home energy auditors and raters, typically certified through programs such as the Building Performance Institute or RESNET, and the assessment usually includes a combustion safety check where the house has atmospherically vented gas appliances. An audit is not a code inspection and certifies nothing. It is a measurement and a report.

There is an order to ask in. Check whether your utility runs a subsidized or free home energy assessment before paying retail for one, since many do. Note that an insulation contractor will normally assess the attic free as part of quoting, which is useful and comes with the standing caveat that the person assessing also sells the fix. An independent auditor charges a fee and sells you nothing but the report, which is what you are paying for.

Buy the audit when at least one of these is true.

• Ducts run through the attic. The measurement you most need is one you cannot take, and it frequently outranks depth.
• The house performs worse than what you measured suggests. That gap is almost always air leakage or ducts, and guessing which is how money gets spent on the wrong one.
• Parts of the assembly are inaccessible. Knee walls, cathedral slopes, flat-roof sections and finished attic rooms cannot be surveyed from a hatch, and thermal imaging is the only practical way to read them.
• The job is large enough that a written scope pays for itself. If you are about to take bids on a whole-attic job, a specification everyone prices against is worth more than the fee, because it makes the quotes comparable.
• You want the before-and-after number. If you intend to prove the work performed, the blower door has to run before it as well as after.

The free survey settles it on its own when all of these hold.

• The attic is open, walkable and fully visible from the hatch.
• It is dry, with no staining on the deck and no damp material.
• No ducts run through it.
• The depth measurement puts you clearly on one side or the other of the level recommended for your zone, rather than near the line.

In that case you already have the answer, and the audit fee is better spent on the air sealing it would have recommended. The payback question covers why this site publishes no dollar savings figure and what does produce one for your specific house.

Work down. The first row that matches your survey is your answer.

The calculator takes your ZIP and floor area and returns the target, the inches and an installed cost bracket, which is enough to sanity check any quote that comes back.

A real share of attics survey clean. Say the material is dry, the eaves are clear, and the depth works out to within about R-10 of the level recommended for your zone. (That threshold is our own estimate, not a measured figure.) Then you have no depth project. Buying an inspection to confirm it is buying a second opinion on a number you already have. Heat flow drops as 1 over R, so the last inches cut far less heat than the first ones did. The useful spend in that case is sealing the ceiling. It costs less than depth, and it fixes the problems depth does not. Air sealing before insulating covers it. We do not sell insulation and we do not install it, which is why this page can end on that.

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A marketing service, not a licensed contractor. Insulation work is performed by independent licensed local contractors.

What does it cost?

A 1,200 square foot attic blown to R-49 runs about $2,600 to $3,200 installed, from this site's own cost model dated August 2026. Two of its parts are estimates, so read it as a range and not a quote. See the full working and the price by attic size.

What happens next?

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First name Last name Phone Email ZIP code Project type Choose one Insulation removalRemoval and replacementRodent or pest contaminationSuspected asbestos or vermiculiteAdd insulation over existingNew attic insulationWall insulationCrawl space or basement insulationAir sealingAttic ventilationNot sure yet Anything else? (optional)

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• The guides hub: the order the work happens in
• Signs you need new insulation, and signs you do not
• How to install attic insulation, including checking a finished job
• Baffles: what they do and how they are fitted
• Turn a depth measurement into an R-value range
• Name the material you found, from the hatch
• What to take up there, and what to measure with