White powder covering insulation in the attic?

During an inspection I found this white powder covering the insulation in the attic. It was up to an inch thick in areas. Does anyone know what this is and why it would have been put in the attic?





Perhaps a drying material any signs of moisture stains under it? or smoke damage.

Also i was wondering if it was some type handy mans pest control.

I did not see any signs of moisture or smoke damage. Pest control could be a possibility. I thought it might be something to cover up pest urine smells. I have been in mice infested attics with a very strong urine smell.


Perlite Building Insulation

The first time I saw it, I thought it was sugar.It looks like that, but is much lighter.

My guess is this is a weapons grade anthrax storage facility.

Make sure your immunizations are up to date and you can start a new ancillary service- anthrax testing.

It kind of resembles the insecticide, preservative, fire retardant boric acid but I’ve never seen that much used or spread like that.


Same here. We have some in my attic that was put there by the company we have contract with but it was a light dusting, nothing like that. That has got to be weighing down the insulation. I suspect overkill in application.,

My first two thoughts were (half jokingly)… :roll:

  1. Baking soda… to get rid of odors from any number of things… :eek:

  2. Lime… to aid in decomposition… :shock:

I would definitely encourage the buyer to have it analyzed before buying the home. The problem with chemical substances is that what was once considered safe may not be considered safe now, such as lead. I sure wouldn’t mind knowing just out of curiosity. I sure as heck have never seen anything like it.

That was my first thought .
The link (2nd) that you provided shows a picture of it in fine granules that looks exactly like the picture.

Possibility – Boric Acid Powder

Read all about it. It’s also commonly used as a fire retardent just like Mike said and I agree it looks excessive.


Could it cause an health hazard to the occupants?

It would certainly present a far greater risk than either radon or indoor mould.

Having said that, it is not likely that the presence of the material (if it is boric acid) would result in a toxicologically significant exposure. Boric acid is a weak acid, and a simple field pH test would certainly confirm whether it had base or acid properties, but would not identify the material. However, if the pH was elevated, you could conclusively rule out boric acid.

Caoimhín P. Connell
Forensic Industrial Hygienist