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Old 02-25-2008, 05:19 AM   #1
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flat built-up roof


I would like to replace my hot tar built-up roof with a better system. the house has two flat roofs, one is 1400 sq. ft. and very low slope of 5/8":12".
the other 800 sq. ft. and 1 1/2":12" slope.
I would like a system that will last longer that the built-up roofing.
What is the best approach, metal, membrane, foam?
Thanks,
Kingcha

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Old 02-25-2008, 05:57 PM   #2
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Metal would not be a good solution for those extremely shallow pitches.

A properly installed single ply membrane would be the best bet, of which, I prefer the PVC or TPO single ply systems and even a fully adhered EPDM rubber roof system would be good for that situation.

Some recommendations:

Duro-Last
IB Roofing
Gen-Flex

Firestone
GoodYear
Carlisle

Photos would help with a precise recommendation though.

Ed

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Old 03-02-2008, 10:34 PM   #3
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IB Roofing Systems white PVC WILL GET YOU A LIFETIME WARRANTY,IS WARRANTED UNDER PONDING WATER,and will qualify you for both Energystar,and LEEDS tax credits,well worth the money---
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Old 03-06-2008, 03:51 PM   #4
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Based on your info that its 5/8" per foot slope on one of the roofs, I'm going to guess its not "tar" as Im pretty sure coal tar pitch can't be installed on that steep of a slope. What you probably have is an asphalt built up roof. There is only one manufacturer of pitch in the states now and there is a long lead time on it.

That being said there is not a better system than a 4 ply built up asphalt roof. Its not uncommon for them to last 40+ years if installed correctly. Think about it....you have 4 layers of felt (reinforcing) and 4 layers of asphalt. Most modified systems are only 2 plys and if you put a single ply on. One ply of protection. One puncture and you have a leak. Theres a lot of single plys out there and there are some good ones such as fibertite and sarnafil, but you can't beat a 4 ply BUR

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Old 03-06-2008, 04:08 PM   #5
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That being said there is not a better system than a 4 ply built up asphalt roof.



You are very wrong about the longetivity of a 4 ply "Asphalt" BUR, (Built Up Roof), being so so long lasting.

Coal "Tar" Pitch is the roof that generates the longest life cycle. It has an extremely low melting point and will "Self-Seal" most minor voids and surface punctures.

But, due to its low melting point, it is only practical on a near Dead Level slope roof. Even a 1/4" per foot slope will allow it to slide and that is one of the reasons that pitch flows over the sides of some commercial buildings. (Not being properly enveloped at the perimeter is poor workmanship which allows this to occur.), but asphalt comes in many "Types".

Type IV asphalt has a higher melting point, but also does not age as well, if left exposed to the sun. Going the opposite direction, bitumen has the asphaltic properties, but the lower melting point of Pitch.

All roofs last longer when the details are done correctly. On a flat roof system, it is more common for leaks to occurr at roof top protrusions and transution points, such as roof tie-ins and curb flashings and along parapet walls. Composition flashings, properly installed, are the key.

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Old 03-06-2008, 04:28 PM   #6
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[/left]


You are very wrong about the longetivity of a 4 ply "Asphalt" BUR, (Built Up Roof), being so so long lasting.

Coal "Tar" Pitch is the roof that generates the longest life cycle. It has an extremely low melting point and will "Self-Seal" most minor voids and surface punctures.

But, due to its low melting point, it is only practical on a near Dead Level slope roof. Even a 1/4" per foot slope will allow it to slide and that is one of the reasons that pitch flows over the sides of some commercial buildings. (Not being properly enveloped at the perimeter is poor workmanship which allows this to occur.), but asphalt comes in many "Types".

Type IV asphalt has a higher melting point, but also does not age as well, if left exposed to the sun. Going the opposite direction, bitumen has the asphaltic properties, but the lower melting point of Pitch.

All roofs last longer when the details are done correctly. On a flat roof system, it is more common for leaks to occurr at roof top protrusions and transution points, such as roof tie-ins and curb flashings and along parapet walls. Composition flashings, properly installed, are the key.

Ed
How am I very wrong? I have looked at hundreds upon hundreds of BURs from doing roof surveys to writing replacement specs. Our company has stood behind BUR's for 44 years and will continue to do so I imagine. The newer modified roofs are made from uncured asphalt, the trumbull type 4 and 6's are cured and age faster. However the 4 layers makes up for it. How many times have you seen a leak from an ac repairman on a 4 ply BUR? I never have. I don't know why everyone keeps calling them flat roofs. There is no such thing as a flat roof. Its low slope. Even pitch requires slope per buidling code. Koppers will allow you to go up to 1/2"/ft with tarred organic felts.

Type I is typically used for the flood coat prior to surfacing. This gives you your lower EVT and some what of a "healing" ability. I didn't mention pitch because like I said its virtually non-existant. I don't think the poster knows what a pitch roof is, so trying to find someone who can correctly install it with felt envelopes, etc. is going to be difficult at best. My point is a mutiply redundant BUR is far superior to a single ply and a modified 2 ply is some where in between
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Old 03-06-2008, 05:15 PM   #7
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You are right about most not knowing the difference.

But Coal Tar Pitch on a dead level is substantially superior to asphalt.

Just a symantex difference maybe. The redundant system, installed correctly, especially all of the flashings, would be my choice considering I have al the equipment to do it still, but to generate experienced mechanics applying it, without an apprenticeship program would be difficult.

A qualified hot roofer, with experience and speed is worth much more to me than any other employee I have ever had.

Ed
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Old 03-07-2008, 07:55 AM   #8
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I'm going to jump in here, mostly because I am impressed to find some people on this forum who really know roofing, but also because I have an extra $0.02 to throw in. I am responsible to maintain about 200 roofs, mostly flat/low slope, mixed with some asphalt shingles, metal and anything else imaginable. We have just replaced the last of our original 3 ply hot asphalt roofs. It was over 40 years old and was done in by a sloppy retrofit of an equipment curb. Our flat/low slope roofs are a mixture of hot BUR, cold BUR, EPDM ballasted, EPDM adhered and few TPAs thrown in because of structural limitations. We also have a huge Asphalt emulsion roof with polyester plys ( a T-shirt roof) that has done an amazingly good job. My experience has been that almost every single ply will leak within 3 years of installation, especially if it's an install on a new building where we have less control of the install procedure. Our preferred replacement is 3 ply cold BUR with composite plys and a flood with gravel surface. We have had the best success with this combination and we fully expect them to last 30-40 years before replacement. Our EPDMs we count as 10 year cycle roofs. The jury is still out on the TPAs as they are too new. I agree that most people don't know the difference between coal tar and asphalt. I have even witnessed a so called roofer using the wrong materials to make modifications. In my area I am aware of several coal tar built ups that are 60-70 years old and still in service. I realize that is not normal, but they are out there. My experience has been that most failures are attributable to poor details rather than poor materials, still I'd rather have 1/2-5/8 of an inch of roofing between me and the water than .045, especially when I have servicable equipment placed on the roof. I guess one of the points I'd like to make is that if we could get 35-40 years out of a hot roof with felt plies, we should get more out of a BUR with composite plies.
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Old 03-07-2008, 11:25 AM   #9
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See, since you are in charge of maintenance, that means that they actually do get historical data maintenance done.

I roofed for a very large Union contractor out of the Chicago area for quite a few years. New construction and tear-offs.

Most of the roofs we did tear-offs on, probably could have lasted double their life, had a proper and diligent maintenance program been in effect.

Is that typical? NO! Out of sight and out of mind.

Roof drain sump deflections, created by building settlement, parapet wall and curb flashings that were burned out and seams that were wide open due to dried our roof cement and loose nails, minor blistering, which could have been avoided during the initial install by not using moist felts or finishing in a wet environment, improper or failing fastening systems for flashings, moisture inhibition due to sheet metal coping cap failures and so on and so forth.

What is the definition of a roof failure?

One leak that no one can find and repair, or a long history of various leaks, continually being patched?

On the single ply membranes, there used to be a saying:
"You only get one chance to do it right!"
Take that to heart during the installation process. The quality of the welds generally are satisfactory, with some exception, due to lack of skill or desire to go the extra mile.

Ain't that the truth. Take a PVC/TPO/Hypalon/EPDM or any other "Witches Brew" they come up with and allow an unconscientious HVAC Service Tech to remove the service panel and place it on the roof, with just one sharp corner. Instant and significant leak.

Now, with a BUR, it may have been able to leak into the inter-plys for quite some time, before the dam bursts and significant observable leakage enters the building. That does not necessarily mean that the roofs life was as long as it took for the final impact of the observable leak. It's life was actually when on its way out, when the first intrusion of moisture ewntered the first barrier of defense, but that would be a hard sell to prove to the man paying the bills, because their is no immediate and direct impact on the internal integrity of the building.

It is easy to find and easy to repair, but the frustration level of the building owner is not subdued, because all they think about, is that the roof system with the 15-20 year guarantee that cost 1 1/2 to 2 times as much as the Asphalt BUR now is leaking.

Ed
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Old 03-07-2008, 12:29 PM   #10
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My experience has been that almost every single ply will leak within 3 years of installation, especially if it's an install on a new building where we have less control of the install procedure. -MAINTENANCE 6

IT SEEMS YOU ADMIT HERE THAT WORKMANSHIP IS PARAMOUNT TO A GOOD INSTALLATION,I agree,I also see that you haven`t had a good install since you`re only getting 3 years,but a properly installed and welded pvc roof will outlast the hot tar,and give better protection--We did thoudands of sq.s of hot tar,both 3 and 4 plies fiberglass,and find it a no brainer to go to the quality single ply roofs for better protection--facts of sloppy or haphazard a/c repairmen should not enter into it,but if it does,It is quite simple to weld a new piece over quality grade pvc,although ,yes the .060,and even the .080 are even better choices--I do not care for the Tpo materials though as they are light,and tend to dry out and become unweldable over time--I`ve seen plenty of "hot tar" roofs not last 5 years as well,but I also realize that the quality of the installation is usually the reason for failure,along with overheating of the tar,to speed up installations ruining the chemical properties inherent in it
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Old 03-07-2008, 02:05 PM   #11
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quote "facts of sloppy or haphazard a/c repairmen should not enter into it,but if it does,It is quite simple to weld a new piece over quality grade pvc"

Perhaps it shouldn't enter into it, but in fact it does. The fact is that sloppy tradesmen work on roofs and they screw up single plies faster than others. It may be quite simple to weld in a new piece to restore the integrity of the roof, but by then I already have a leak that I wouldn't have had with a more bulletproof type of roof. I've not seen an HVAC tech slice up a 3-4 ply built up with an access panel. I HAVE seen it on more than one single ply. There are places for single ply. When budget is a major concern. When there is NO foot traffic. When penetrations are few and straightforward. When there is no servicable equipment on the roof, especially refrigeration eqiupment. Then they may be the answer, but so far I'm not convinced that they will outlast a properly installed BUR. ................And the next guy I want is the jerkweed who invented the IRMA.
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Old 03-07-2008, 02:18 PM   #12
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Yes Ed. We do an annual walk around maintenance program to address loose flashings, missing or loose counters, check clamping rings, clean drains, and recoat flashings. Some of our first Cold 3 ply BURs have been down for 14 years and they still look like new. That is why I'm convinced they will go for 30-40 years. Some of our biggest problems come from window washers dragging drop lines around flashings and tearing up corners.
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Old 03-07-2008, 03:12 PM   #13
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And the next guy I want is the jerkweed who invented the IRMA.
Green roofs with garden on top are the IRMA's of our near future.

Yes, they are instaling them with low growth vegetation and rootings and yes they install the mesh underlayment and yes, some are now going to sectional pull-out pieces, but if you have ever tried to find a leak under muddy gook, it is nearly impossible. Also, getting it clean enough to be able to properly patch it will test someones perserverance.

Another thing, even though the implanted vegetation is not long root growth plant life, what about the other organic debris which will find its way to the garden roofs and then start growing trees with roots puncturing the membrane.

Landscaping and roof maintenance, all built in one.

Maybe that is why the border fence is not built yet.

Ed
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Old 03-07-2008, 03:27 PM   #14
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We have 2 roof gardens scheduled for completion in spring of '09. Yippeee

I fought them, but you know how architects are. As long as it looks pretty for the ribbon cutting, that's all that matters.

.............and don't even get me started on plaza decks.
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Old 03-12-2008, 01:58 AM   #15
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Quote:
Originally Posted by ncgrogan View Post
Based on your info that its 5/8" per foot slope on one of the roofs, I'm going to guess its not "tar"











Yes you are correct, it is a hot asphalt built up roof - 4 plys and I've gotten 18 - 20 years life out of two tear-offs, hence the reason I'd like a different system that will last beyond this. I don't want to be replacing a roof in my retirement 15 years from now!

I have some info you guys may be interested in. I am a machine designer of industrial production equipment. A few years back I did a job for a roofing manufacturer - Bird & Son which was purchased by Genstar which was again purchased by Certainteed. The project involved diluting the asphalt with very fine powdered limestone to reduce product manufacturing cost. Initially the asphalt had 30-40% filler (limestone dust) Equipment was put in to increase this to 60% filler. So there is just enough asphalt to bind the granules to the fiberglass sheet which went down a continuous line and was rotary cut into 3 tab shingles. I would imagine if the other shingle manufacturers are doing the same and they most likely are to reduce cost given the high price of asphalt (oil), I would think the longevity of shingles is going to suffer in the future. Typical, not only is the price going up - the quality is coming down.


By the way it is interesting to note that the site of this roofing plant was an old WW ll Army base that was converted to an industrial park after the war. Some of the orginal barracks were still in place with felt matt asphalt shingles from 1942 (used before fiberglass matt of course). The roofs though weathered, were still in service after 60+ years! I think they used pure asphalt, no filler back then (in 1945 oil was $1.05 a barrel and asphalt was a waste product of the refining process)

Thanks for all your help,
Kingcha


Last edited by kingcha; 03-12-2008 at 03:24 AM.
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