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Old 08-20-2009, 10:04 AM   #1
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New Modified Bitumen roof - please help


Good Morning,

I recently purchased a townhome in Washington DC. It needs a new roof and my potential contractors are pushing modified bitumen. I looked at rubber, but was told mod. bit is tried and true.

I'd like a no maintenance roof, so does a white, 2 ply APP, granulated, modified bit sound like the way to go?

I'm new to this stuff, but have been reading a ton. Is APP better than SBS? What ply is best in terms of longevity? Any suggestions or tips are appreciated.

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Old 08-20-2009, 11:15 AM   #2
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New Modified Bitumen roof - please help


Townhouses are a special case because unless there is a parapet firewall projecting above the roof there is often moisture coupling between the roofs of adjacent units - it doesn't matter how good a roofing job is done on your unit if moisture from adjacent units is getting under your roof membrane.

That said, if you're going to stay there more than 10 to 15 years I would consider PVC, here in Chicago the realistic life of even a well installed modified bitumen roof is 15 years, and is not unusual for me to see them having problems after 10.

OTOH I've never seen the material fail on a PVC roof (only installation defects) and some of these roofs installed in Europe 50 years ago - with materials less sophisticated than those used today - are still going strong.

The problem is finding a roofer experience with PVC who is willing to do a small residential job - I'm only aware of one in my area - and that some manufacturers of PVC roof membranes do not warranty them for non-commercial application.

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Last edited by Michael Thomas; 08-20-2009 at 11:34 AM.
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Old 08-20-2009, 04:23 PM   #3
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New Modified Bitumen roof - please help


Michael Thomas obviously has a lot of lower quality roofers in his area because modified doe's very well in my area and easily last 20 plus years if properly installed and maintained.

I also prefer single ply systems over the mod tho, it's less wait on the roof and properly installed will last the same or longer as modified.

You stated your looking for a maintenance free roof, there is no such thing.
Every roof system requires some maintenance eventually in order to achieve it's manufacturer suggested life span.
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Old 08-20-2009, 08:05 PM   #4
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New Modified Bitumen roof - please help


Quote:
Originally Posted by Slyfox View Post
Michael Thomas obviously has a lot of lower quality roofers in his area....
Of course we have highly skilled roofers in Chicago, DYI Chatroom is lucky enough to have one of them, "Ed the Roofer", as a regular contributor.

And of course when I turn up with my thermal camera and my ladder, it's not because one of them did the job, it's because the job was done by the three kludges on a weekend bender.

Quote:
Originally Posted by Slyfox View Post
... because modified does very well in my area and easily last 20 plus years if properly installed and maintained.
Well there's the catch, Wednesday's inspection is typical:

I routinely scan top floor ceilings under flat roofs:



Fig 1. Yup, there are active roof leaks, but what's the cause?



Fig 2. Up on the roof, walking over toward the first known leak,
we find Clue #1



Fig 3. A few steps further, we find clue #2



Fig 4. And at the first leak site we find this "repair".

Well, that was easy...

The moral of the story is that real world, down in the "city", seams in modified bitumen as actually installed are going to fail, and that Mr. Tar Bucket and Mr. Cheap Caulk will be up there performing the repairs.

And in my experience, the seam in PVC are less likely to fail, if only because the installers working with this material are on the average more competent.

YMMV.
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Old 08-20-2009, 11:29 PM   #5
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New Modified Bitumen roof - please help


Sly,

Most of the home owners and landlords in Chicago do not hire professional roofing contractors, but rather they hire someone that says they can put on a roof for them, if you get my gist.

But, I have also seen many sloppy and totally useless seams in PVC membranes and Hypalon along with epdm.

The benefit of the hot air sems, is that once they are discovered, IF they contact a professional, the repair is quite simple.

Many seams I have seen were patched with caulking or roofing cement.

Now, even with the modified bitumen roof, any true roofer would know that plastic roofing cement is not suitable to provide more than a temprary repair.

But, the landlord or home owner got a good deal and for at least one night, when it wasn't raining, their roof didn't leak.

Ed
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Old 08-21-2009, 08:13 AM   #6
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New Modified Bitumen roof - please help


As usual you make since Ed and I agree with you, but it's all about the installer not the material.
Michael Thomas stated the system 'Modified' fails, meaning the materials are inferior but I personally have repaired my own work on 20 plus year old Modified thus the suggestion that the product won't last 15 years obviously is not a fact.
Just like his pics and explanations, he's again speaking about the system failing as he is showing pictures of workmanship failing.
If the same roofer who installed a mod roof that didn't hold up but 10 years or so before it failed installed a single ply it would fail in 10 years also.
A bad roofers gonna give poor quality no matter what materials he's using.


Edited to correct the time frame statement.
The MOD roof I repaired last year is only 17 years old.
Tree branch fell and ripped the gutter down and did some minor overhang damage.
I don't have any older than that except for when I worked for Simon Roofing, but I was just a journeymen on those jobs.
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Last edited by Slyfox; 08-21-2009 at 08:37 AM.
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Old 08-21-2009, 08:19 AM   #7
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New Modified Bitumen roof - please help


(Of course we have highly skilled roofers in Chicago, DYI Chatroom is lucky enough to have one of them, "Ed the Roofer", as a regular contributor.)

LOL, I didn't say you had no quality roofers in your area.
If the majority of the roofs are failing in 10 to 15 years you obviously have more lowly skilled than highly skilled is all I was saying.
Yes, we have our share of less than quality roofers in my area also.
I guarantee Ed was not the roofer responsible for the work in those pics you showed.
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Old 08-21-2009, 12:34 PM   #8
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New Modified Bitumen roof - please help


The same can even be said about the evolutions of my company and employees experience.

Although I am proficient at all of the systems that I discuss, I would not have some previous or current employees or crews work on those types of projects without sufficient training and 100% continuous on the job oversight by myself or someone else I would hold in deep regard to supervise.

Even with small modified jobs we do now, I ensure that I am there for the difficult or dangerous detail work where things could possibly go wrong and become a disaster.

Just because someone can figure out how to pull the trigger on a torch does not insinuate that they have any knowledge at all about proper instalation methods of applying APP torch down modified bitumen roofing materials.

The ones that do it correctly are the very extreme rare individual.

The biggest problem with modified bitumen systems is, that it seems so easy to do, that just about anyone thinks that they can do it suffiently well, but that is far from the truth.

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Old 08-22-2009, 04:49 AM   #9
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New Modified Bitumen roof - please help


Quote:
Originally Posted by Ed the Roofer View Post
The biggest problem with modified bitumen systems is, that it seems so easy to do, that just about anyone thinks that they can do it sufficiently well, but that is far from the truth
That ought to be the first line of every manufacture's installation instructions, in bold.

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