Modified Bitume I.D.

[Denray]

I check to see if roll roofing is MB by tearing on a piece of it. If it tears like cardboard or easier I figure its not.

A responce to my email to Johns Manville suggests it may be more difficult than that.

There is not a very good way of telling the difference between Modified Rolls vs Unmodified Rolls but there are a couple things one can look at such as thickness and tensile strength. Modified rolls are typically thicker than unmodified rolls. Also, because the modified rolls may have different reinforcements, in some case they may have more stretch than an unmodified roll. These types of in field analysis can be very subjective though. To get a definitive answer, there are independent testing labs out there that can investigate the type of material in the asphalt of the roll to determine if it is modified asphalt or not.

Followed by

The ease of tear could be due to the difference in thickness of the sheet. Ease of tear may be due to the reinforcement of the material in combination with the thickness of the material. Modified rolls are reinforced with fiberglass, polyester, or a combination.

What are your folks ways of knowing?

[caryseidner]

Denny,

If you go to your local roofing supply yard and look & touch the material, it is unlikely you will ever have questions about it again. Not trying to be too sharp with you, but it's really just that simple.[]

[Denray]

Yes, I felt pretty confident about it till my wife who does independent adjusting looked at wind damaged roofing belonging to a contractor. She brought a piece of the roofing home and it tore fairly easily and was on the thin side. The contractor said it was MB. Since my wife uses a different last name he does not know she is married to me. I told her no way. So she took the only sample she had and left it with the roofer that the contractor wants to use and he also said it was MB. So I thought maybe I don't know for sure how to I.D. it. So I sent the email to JM. They don't seem very confident in their reply?

I'm betting that the contractor is just trying to put one by on the ignorant female adjuster. She gave up the fight after the roofer said it was MB. This contractor does a lot of work for insurance companies that my wife works for. She didn't want to rock the boat too much.

P.S. I used to be an insurance adjuster and it is just par trying to rip off the insurance company as much as you can get away with.

[caryseidner]

Denny,

Modified Bitumen is usually about 3/16" thick. It is made by dragging fiberglass/polyester sheets, or scrims, through a proprietary mix of bitumen and plasticizers. As the mix cools the material is cut and rolled and then shipped. Obviously this is a simplified description. The point I am trying to illustrate is that the sheets are relatively thicker than most flat roofing products. The scrim(s) and plasticizers make it difficult, if not impossible, to tear with your bare hands.

[Erik]

Denny,

Modified Bitumen is usually about 3/16" thick. It is made by dragging fiberglass/polyester sheets, or scrims, through a proprietary mix of bitumen and plasticizers. As the mix cools the material is cut and rolled and then shipped. Obviously this is a simplified description. The point I am trying to illustrate is that the sheets are relatively thicker than most flat roofing products. The scrim(s) and plasticizers make it difficult, if not impossible, to tear with your bare hands.

I disagree with the thickness. Around here it comes in three different weights first one 2mm second is 3mm and third is 4mm.

[Denray]

Thanks guys. Erik, is the 2mm still fairly tough to tear?

[caryseidner]

Denny,

Modified Bitumen is usually about 3/16" thick. It is made by dragging fiberglass/polyester sheets, or scrims, through a proprietary mix of bitumen and plasticizers. As the mix cools the material is cut and rolled and then shipped. Obviously this is a simplified description. The point I am trying to illustrate is that the sheets are relatively thicker than most flat roofing products. The scrim(s) and plasticizers make it difficult, if not impossible, to tear with your bare hands.

I disagree with the thickness. Around here it comes in three different weights first one 2mm second is 3mm and third is 4mm.

Erik,

The thickness is aprox., but GAF's standard grade (Ruberoid APP Smooth) is 3.8mm or .148" or about 5/32" (1/32" less than 3/16"). They do maker thicker sheets, but I've never seen anything thinner. No way on the 2mm. By the time yo put a torch to the backside of that product it will vanish!

But what you're not going to convince me of is that you can tear the sheet with your bare hands....even if it was 2mm.

[caryseidner]

Incidentally and coincidentally, I just received the current copy of the ASHI Reporter. There is a featured story in it on "Flat-Roof Inspection, with a Focus on Mod. Bit." You guys should read it if you have access to it.

[Denray]

That's what I always thought. Just wanted to make sure I wasn't having a senior moment.

[Tom Raymond]

The most common plastcizer used in thermoplastics is lead. What do they use in mod bit? Lead is not nice stuff to put a torch to, it vaporizes at around 1100 F, easily reached with a heat gun let alone a roofing torch.

Tom

[hausdok]

Hi,

It sounds like what one large roofing company here calls glass mat. It's essentially a really stiff building paper with a fiberglass mesh reinforcement. Around here, the hacks that use that stuff put down a layer of mastic, lay that stuff in it and then slather on a surface coat of mastic, kind of like doing a BUR, and call it a roof. It lasts about 6 to 7 years. It's cheap and quick.

The stuff is pretty thin and it tears easily. I have no idea whether it's a modbit product or not but I can tell you that it makes for one lousy cover and I can't even imagine blanching it with a torch.

You might be seeing something different though - something that's not a real modbit but isn't glass mat or anything like it.

Wouldn't it be simplest to just go to the roofer and say, "Yo Bro, show me the stuff you used on so-and-so's roof and look at the packaging and then google it?

ONE TEAM - ONE FIGHT!!!

Mike