Sand-like covering substance separated from the flat roof (done 2015)


I was walking around the roof, with water on the roof from melting snow - I noticed blue sand! The sand like covering on the flat roof has separated from the material due to standing water? I am wondering if this is normal and what level of severity should this be.



The granules (what you call sand) protect the roof covering from the sun’s UV light. The loss of granules and thus UV protection will accelerate the rate of drying of the roof covering and thus speed up its cracking/splitting which then causes leaking. It looks like modified bitumen roof which last 10-15 years. If it’s up there in age, repairing that section alone is useless. Time to save up some $$$ for replacement of the roof covering.


Pretty normal on a Sand roof for the sand to move during low tide. The sand will probably come back when the tide comes up.

Morning, John. Hope to find you well and in good spirits today.

Kenton Shepard has written articles on asphalt shingles and roll roofing. The sand like aggregate is ‘Protective Coating’ - ‘Mineral Granules’’ to defend the bitumen asphalt/polymer from Ultra violet ray and weathering.

I will refer you to, Inspectapedia. How to Inspect a Roof for Loss of its Protective Coating of Mineral Granules

Daniel Friedman - Publisher & chief editor of/at InspectAPedia has been a great resource for InterNACHI members as well as the home inspection community for decades. I would Book-Mark InspectAPedia. Great resource.

Hope that helps.
Regards. Robert.

It’s a brand new roof (barely three years old), it MAY be normal! “If the roof is reported to be new, the granules shown in our photo are normal and not a worry.” - Thanks!!

Modified torch roofing. Roofers spread granular atop hot tar that oozed from the seams.
I have several images of what you describe.

Observation: Excess granular on the roof.
Roofers spread granular atop hot tar that oozes from the torched seams to give the roof covering a more uniform appearance.
No adverse conditions observed, if there were no adverse conditions observed.
We where informed by the vendor, the roof covering is 3 years old.

They are supposed to do this. I call this out all the time when I don’t see it. Lack of granules at seam bleed-outs and repairs is a sign of poor workmanship, since it shortens the working life of the underlying material. I consider it the sign of a lazy roofer. If I see it, I bring it up in my report. There’s really no immediate need to re-do it, since the bitumen has long hardened up by the time I’m up on the roof. But, it’s still a sign of poor workmanship, and I talk about it.

Side note: I’ve been on roofs undergoing warranty repairs, and they were quite liberal with the granules. So just because there are loose granules present, doesn’t mean the roof is wearing prematurely. You’d need to see bare spots to make that conclusion. Just seeing excess granules could be a sign of liberal application of granules during the original install or a repair.

Are you saying granules over seam bleed-outs are required? if so, by whom? and why?

JM calls for it, GAF calls for it. Certainteed says “may be applied”. Tremco makes no bones about it and calls for it. Most manufacturers call for it in their manuals.

I looked at JM’s manual and could not find it, I looked at GAF, and like others, at best they say:

“Matching granules may be broadcast into the modified bitumen bleed-out at seams while hot to enhance the finished appearance of the membrane . It is not required for issuance of a GAF Guarantee”

Please pin point me where (with a link) anyone calls for the bleedouts to be covered with granules other than for aesthetics, which is not a “requirement”.

I do know what they call for and it’s not what you are saying, at least I have never seen it.

1 Like

From JM’s manual: “Be certain to achieve a minimum 1/4” flow of melted bitumen from the overlapped seam and allow at least 1/4” extra lap width at the side laps so that the smooth side lap provided is completely sealed and still aesthetically neat. Loose slate granules are provided to dress the bitumen at the seam area while still warm.”

Also, the words “not required for issuance of a GAF Guarantee” don’t show up in the GAF installation manuals.

From Tremco:
“A 1/8” to 3/8” (3 mm to 10 mm) bleed out of bitumen extending beyond the edge of each lap is required. Immediately apply matching granules into this bleed out along all side laps and end laps.”
Page 26

It’s all in China now but it will be back soon enough… :upside_down_face:

1 Like

I concur.
Seen bleed-out with and without sprayed mineral.
Bleed out bitumen/polymer is atop manufactured granular minerals. I see no defect or avoiding manufacturers installation methods that would void warranty…

I call out detached or seam delamination.

Just my 2 cents.

That’s for ‘hot mop applied’. Not torch on or hot seam.

They do, for both APP AND SBS types:

“Matching granules may be broadcast into the modified bitumen bleed-out at seams while hot to enhance the finished appearance of the membrane . It is not required for issuance of a GAF Guarantee”

Page 96 paragraph I

Page 98 paragraph I


“I. Matching granules should be broadcast into the modified bitumen bleed out at seams while hot to enhance the finished appearance of the membrane.”

I agree that large bleedouts should be covered, however, 1/8-1/4 bleedout along the edge of a bitumen roll is nothing more than a visual indicator that the seam was properly executed and will not impact the performance of the product if not covered with granules.

May be broadcast being the underlying theme.