Dibiten vs. GAF Modified Bitimen Material

Hello all.

I have 4 buildings that I am looking to tear off and replace the entire roofs. They are split roofs with one half a decent pitch and the other half a flat low pitch area. (I believe the pitch is 1" per 10 feet)

I have had 2 contractors out to look at the projects. **Regarding the flat roof portion **one wanted to use Dibiten Poly/4 and the other wanted to use a grandulated Modified Bitemen GAF product.

I am trying to make a decision on which product to use. I understand that if I use the Dibiten product that it will have to have a reflective coating every 3 to 5 years.

I originally wanted to use a rubber sheathing product by Firestone but they said this was not a material to be used in my particular application.

I am looking to see if you all have any thoughts on which product might be the most durable and last the longest - especially if you have used both products - in my particular circumstances. I live in Indiana so I get all extremes of weather.

I look forward to your thoughts. :slight_smile:

Well, if it is pitched enough for modified bitumen, it is itsched enough for rubber. They probably do not do the rubber, so they will say anything to get you to go with their product.

What are your criterion for tearing off the existing roofing? Is there leakage and rot? Is the current system falling apart? Might a spray applied monolithic membrane be a better match for you?

I personally haven’t dealt with Dibiten in over 12 years, but to answer your question a modified bitumen roof system is a very good roof. The reason they probably stated that rubber is not a good option, is because you likely have a commercial building that has several roof-mounted HVAC units or has a fair amount of foot traffic. EPDM (rubber) is generally a good roof system for warehouses and such, and it is only as good as the contractor installing the system. The redundancy of a built-up roof, or a built-up roof with a modified bitumen cap sheet provides you the most protection, and these roofs over time have proven to be the best low-sloped roof systems.

Now, I’d be curious to know what kind of building you have, i.e., office, strip center, warehouse, etc. Does the low-sloped roof set higher than the sloped roof, or is the low-sloped roof surrounded by the sloped roof and the sloped roof drains onto the low-sloped roof? How high is the low-sloped roof above the ground? Are the contractors talking about installing a built-up roof with a modified bitumen cap sheet, a single-ply mod. bit. roof, or a 2-ply mod. bit. roof? The more information you provide, the more help I can give you.

I have to again, disagree…and I do not even do a lot of EPDM. EPDM is just fine for HVAC units, and may be better considering the elongation factors compared to BUR (my favorite system) when dealing with HVAC vibration and movement. As with any system, they are only as good as the installers, not just EPDM…And Coal Tar Pitch is a better system than BUR/mod bit hybrids or EPDM. FWIW

You can disagree if you like, but I’m telling you EPDM is not a forgiving system. It is more apt to be damaged by HVAC workmen and leak than a BUR. Also, you can have a dry lap in a BUR and not get a leak, but have a poorly sealed lap in an EPDM roof and see what happens. FWIW, coal-tar roofs are BUR roofs also, so when I was saying that BUR’s are best that that would obviously include coal-tar; I would have thought you would know that. Anyway, I think everyone here will agree that coal-tar is the best roofing bitumen around, but not everyone will agree that it is best for every system. BUR roofs are the most tried and true low-sloped roofs statistically speaking.

So, back to helping the person who asked the original question; if they can tell me more about their building or show photos I can give them sage advice as to how to proceed.

IS there anything you guys agree on or what?

I agree, cerb, but simply put, do not agree that we shall make excuses for faulty workmanship in any of the systems, nor for careless HVAC service people.

There, gtpe, we agree. :slight_smile:

Yes, there are somethings we agree on, but the biggest problem is Aaron feels like since I’ve started posting here that I’m pissing on his fire-hydrant. He has most of you guys in here trained to defer all low-sloped roofing questions to him, and he doesn’t like the fact that there is someone else here now that gives differing opinions on low-sloped roofs. He doesn’t like the fact that I don’t like SPFs, and I’ve admitted that I don’t know much about polyureas, two systems that he keeps pimping. Now, where I take exception with Aaron is when he states that I’m full of sh*t or wrong, just because I don’t agree with his opinion. Rather than agreeing to disagree, he tries to give people the impression that he is always right. That is just not the case.

Now as for Aaron agreeing with me about EPDM roofs being easily damaged, and not being very forgiving with regard to poor workmanship. No, we can’t make excuses for either of those, but they are both real world concerns on roofs. There are roofers that don’t properly clean or glue together EPDM laps, there are HVAC and other workmen on roofs that damage the roof membrane, etc.

Hey Cerb,

I do not FEEL when posting, especially not that youre pissing on my hydrant. I am here for one reason…to promote best practice roofing instead of the common ways of doing things which most often result in failure. I have a total of ONE sale resulting from this site in the few years I have been here, so please do not say that horsechit about I am here to sell my wares.

Yes, I think youre full of crap some of the time…like when you told that condo owner in Florida to cut all their flashings on their new roof (which was installed without insulation) because if the additional roof to be installed ever leaked, it is better to leak into the building than have it on top of first new roof (instead of regualr maintenance and inspections that would detect such a condition). I thought this was whack. I told you so.

BUT, if you ever notice…on the subjective comment on the subject of you stating that I think Im always right…if there is a subject I am not familiar with, I do not post…that is because I am not knowledgeable in that area. Ask some PVC questions, and TPO questions…I will not likely respond, unless I, too am asking a question.

As far as wanting everyone to defer anything to me…youre making that up. I know, for one, roofboss has more experience, and probably knowledge than you and I combined.

Roofboss also does not like SPF. Heck, I didnt like it either, until I actually studied into the system, its drawbacks, application, and reasons for failure. I had never been called out to repair a non-failed SPF roof, which I am guessing you havent, either. Does this mean that SPF is bad? To you it does, but if it is so bad, why doed the NRF statements say that it has an indefinite roof life cycle? Do you think that they have been bought off by the SPF mfg’s? Or might they be an impartial body? You specify polyurethane foam all the time…its just that you either dont realize it, or cannot figure out why SPF works and you have probably never seen a good one.

I think that you are the typical consultant that, when they are ignorant on a subject area of your supposed expertise, you will intentionally degrade another system rather than admit youre ignorant on the subject. I understand…you have to save face being a consultant and all. :frowning:

Now who is full of sh*t? I’ve already admitted that I don’t know much about polyureas.

And fwiw, I too am here to promote good roofing practices. I spend most of my time investigating leaks and failed roof systems, so I know what works and what doesn’t work. How much of your time do you spend investigating roof leaks? Unlike you, I have not netted a single sale from this site, that is not my purpose for being here.

Anyway, thanks for clearing things up and confirming what I’ve always suspected about how you feel regarding consultants. I’ve long suspected we in some way intimidate you. However, in my opinioin you really shouldn’t feel that way, you’ve proven that you have a good roofing knowledge base. You don’t know everything about low-sloped roofing like you believe, but you are fairly knowledgable. Of course, I also think it is sad that you try to give yourself more credibility by attacking me.

As for the condo owner in Florida, I don’t remember the posts exactly, but I think the point I was making was not to sandwich new roof insulation between two roof systems. This is a point you obviously don’t agree with me on, so I won’t argue the point with you, but it doesn’t mean you are right and I am wrong. You obviously believe it is better to be oblivious to a leak as long as it isn’t dripping inside, whereas I would rather know the roof is leaking so it can be addressed and patched before it ruins all of the insulation.

gladiators ready!!!1

Well one thing is for certain. You always have 2 different looks at how to go about fixing flat roofs on this site. I dont know enough to comment on either way since im just a steep slope guy. Only thing i know about flat is flintlastic and i know thats not what is needed here.

[quote=“Cerberus”]And fwiw, I too am here to promote good roofing practices. I spend most of my time investigating leaks and failed roof systems, so I know what works and what doesn’t work. How much of your time do you spend investigating roof leaks?

Almost all of my working time, since my entire business is now based on roof repair.

Intimidate? Nah…most consultanbts I have had the pleasure of meeting have been bookworms, with little working knowledge of roofing. YOu do not seem to be a member of this class.

Negative. I seek no credibility in this…just accurate information.

Once again, negative. You assume me to beleive this. If you re-read my post and take it literallly without adding your emotional version of it, you will see that I suggest regular inspections and mainteneace to alleviate this type of issue. Besides, I would rather replace a bit of rooftop insulation IF the primary roof leaks, rather than drywall, interior insulation, computers, other electronics, grandma’s keepsakes, etc. This situation can be found during routine checks. This makes more overall sense to me.

I will agree with you that routine checks make more sense, but you and I both know that most people do not worry about their roofs until they leak.

As for consultants being book worm types, I also agree that many are book-read consultants, and I too do not respect them. As I’ve stated before, I was a roofing laborer/foreman/superintendent for over 10 years before I became a consultant.

im just sick of hearin that plastics and foam and rubber and such are good roofing products.
well there not.
let me say that again.
they are not good roofing products.
theese materials just simply burn up in the sun, unless your up on your roof every year protectin it, and what sence does that make? none.
and they do get tore up easier when people go up there to do service work.

do yourself a favor and get your self a good 3ply fiberglass built up roof with gravel, and be done with it.

22 years in service withour failure is not a long life? And it is still going, so they tell me.

I think you should investigate, gweedo. The aromatic polyureas do not degrade any faster than you fdavorite (and my former favorite) modified bitumen. The aliphatics last even longer, but are considerable more expensive.

You will have to recoat smooth three or four times before you have to do anything with our Aluminum polyurea/urethane hybrid membrane at equal thicknesses…

This is eemperical data, not just theory.

foams, plastics, rubber products, are the roof products of the future, so its hard for me not to like them.
for now though, im not wantin to see it sprayed and coated on every roof.
up and over, on a slight pitch, no penatrations, under some shade trees. yes.
on a comercial flat, with a bunch of A/Cs. no.
i have worked on alot of foam roofs, torn alot of them off, my freind sprays them on as we speak. im sorry but its not as durable as 3ply glass.
it mite be one day.

me personally, i wont ever be able to do none of them, foam , plastic, or rubber.
i sweat to much. between my sweat and the constant rain tampa bay, roofs i do must be able to be appllied to wet surfaces.


p.s. cant stand to see it sprayed over tile, god that looks hideous.

I am talking polyureas membranes. You are talking polyurethane foam? Two different animals.

Hi again everyone - I appreciate all the responses. I quess I wish things would have remained more on point then becoming a session of who is right and who is wrong.

Like anything in life we all have our own opinions and experience. Expressing these thoughts are what I think most posters on this site are looking for - let them make the final decision of which way they want to go with their particular project.

Again, thanks for all your thoughts and I wish everyone a Happy and Peaceful Thanksgiving!!