Rock wool?

tlarsen · June 4, 2011, 5:29pm

60+ year old house. Original faced wall insulation.
Is this faced rock wool, or dirty glass?

TIA,
Tim

Brian_A.MacNeish · June 4, 2011, 6:44pm

By the colour and if original, I’d say “rock wool”

jhagarty · June 4, 2011, 7:55pm

gray black
Rock Wool…
better than fiberglass…

tlarsen · June 4, 2011, 8:20pm

Thanks, guys. I thought so, but I’ve had no previous experience with it.

Cheers,
Tim

belliott · June 4, 2011, 9:21pm

Learn how to do it the easy way.
Mineral wool/fiberglass type material.

ccurrins · June 4, 2011, 9:23pm

It’s not Perlite.

jjonas · June 4, 2011, 9:24pm

-X-X-X

jhagarty · June 4, 2011, 9:28pm

???
rock wool
no comparison

ccurrins · June 4, 2011, 9:35pm

Brian_A.MacNeish · June 4, 2011, 9:44pm

Reasons?

I tend to rate them as near equals for R value & installation except when it comes to cost…rockwool batts are more expensive than fiberglass batts here!!

With higher R values (up to R50 in attics) in todays’ much more efficient homes, the extra weight of the heavier blown rockwool on flat attic surfaces may require 5/8" drywall or thicker on the ceiling.

For example: 1 brand of rock wool I looked up had a weight or 2.68 lbs/sq ft for R34. Cellulose is 1.23 lbs/sq ft for the same R value.

jhagarty · June 4, 2011, 9:45pm

???
pic in first post looks like perlite?
???

jhagarty · June 4, 2011, 9:47pm

all insulation is inadequate at best to the claimed ® values.
Installation methods may vary…

sgilligan1 · June 5, 2011, 2:16am

The easy way to tell is to take a hot shower after you get home from the inspection. If you start itching so bad you can’t write up the report, it was fiberglass.

jjonas · June 5, 2011, 4:08am

Perhaps a “tongue-in-cheek” reference to this thread… Attic Insulation - General Inspection Discussion - InterNACHI®️ Forum

BTW… post #13 is still awaiting your reply.

ryoung7 · June 11, 2011, 9:17am

I agree with you hypothesis on the 5/8 wallboard.
Imagine the weight the the RW will have if it carries moisture.
Q: What is rockwool?
A: Rockwool is spun mineral wool fiber. Various “rock” components, with a heavy dose of silicon oxides are melted at high temperature and fibers are formed as molten material is passed by a series of “spinners.” The finished product which is “bonded” via proprietary resins, is inert, meaning it has no cation exchange capacity. Approximately 97% v/v/ is air space. Bonded products (plugs, blocks and slabs) also contain a wetting agent, which may (absorbent) or may not (repellant) be present in granulated (also called flock) rockwool.