Cracks in wall or ceiling exposing fiberglass -- health threat?

Suppose there are places in a wooden wall or ceiling (or maybe a slight gap where a wall meets a ceiling) where there are slight gaps (1/16-1/8 of an inch). Behind the wall or ceiling is fiberglass insulation. Does this pose a health threat?

No. I’d be more concerned about the cracks in the ceiling; could be a sign of structural damage.


opening can occur from settling. monitor the situation.

often home interiors will have those kinds of tolerances, it isn’t cabinetry, it is the width of a saw blade and less. trim pieces can cover and those cuts done to closer measure because there are fewer pieces. if you don’t want trim caulks or filler could be used.

If the fiberglass is disturbed by air or physical contact, the fibers aren’t particularly good for your lungs.

Ceiling insulation is often blown in cellulose rather than fiberglass. Either way, exterior insulated walls usually have a vapor barrier on the interior side that is going to prevent any insulation particles from getting to the interior. Joist spaces where the wall and the ceiling meet are often spray foam insulation, if fiberglass they will have vapor barrier. Gaps between wood joints and edges of vapor barrier are all sealed with an acoustic caulk.

For interior walls insulated for sound, the insulation is still in in the spaces of the framing; where ever a wall meets a ceiling or other wall there is just wood. Any joint in drywall (or wood paneling) will always be over a framing member, (otherwise it would be loose). Cracks in drywall are usually due to improper or failed fastening, and require screwing and taping to fix properly. Cracks due to movement can be fixed similarly, but will re-occur if settling is not corrected.

Fiberglass dust is definitely bad for you, but so is pretty much all dust to a greater or lesser extent.

I came across that link as well, but the National Association of Insulation Manufacturers didn’t seem like the most objective source.

As for other responses, let’s not focus on what care should have been taken to eliminate cracks – caulking, lining, etc. The question is regarding a situation in where there ARE gaps between very old tongue and groove boards exposing insulation. Would you regard this as a health threat? If so, how serious?

It could only be a problem if something disturbed the insulation and thus sent particles into the air. If you’re concerned you can probably seal the gaps with something. Caulk is a common and relatively cheap solution, and it keeps the insulation undisturbed. If the crack is between wall and ceiling a decorative molding could be applied.

As for how serious - that depends on what the insulation actually is composed of. True fiberglass is highly irritating. Other types of insulation could potentially cause allergic reactions. Dust of any sort can worsen asthma or other chronic lung problems. Very old insulation might contain asbestos, which of course is definitely a Bad Thing. The risks will vary with the insulation composition and how much of it is getting into the air. Some types are very low risk, but unless you know exactly what’s in it, it’s hard to be more than just vague.

None of these would be Sudden Death to touch, but as a general rule keeping dust at bay is a good thing.

To repair, or more accurately seal such cracks, a paintable acrylic caulk would be the most common method. It is easy to use and cleans up with a damp rag; silicone or urethane caulking can be very messy, and can t be painted. There are clear varieties available if the wood is stain grade, if it is going to be painted, white is more common. It is available in both tubes for caulking guns and squeeze tubes, which are easier to use when final appearance is important. Dap is a common brand.