Foam or Mod Bit Torch Dn?


#1

I have an existing foam roof, 8 years old, needs to be torn off I’m told due to constant blistering (bad mix on install) and very unneven causing pooling in areas. Latest roofer strongly suggests Mod Bit torch dn. I’m in Phoenix (hot), big house 6k sq ft (2k of which is flat roof, rest 90lb flt w/tile), so energy save is a factor. Can someone plz give me some point of view on wthr I shold stick with foam, or switch to Mod Bit Torch Dn?
Much thanks!!


#2

At this point you are pretty much committed to foam. That is one of the things I do not like about foam, i.e., once you put it on you can’t change to another system without paying a lot of money to have someone scrape every inch of foam off your roof and penetrations. Anyway, have the roof scarfed down and more foam sprayed on and then coated. You will also want to maintain the coating periodically to extend service-life of the roof. However, with that said I have to say in my opinion an APP modified bitumen roof system is a better roof system than the foam.

For more foam roof information you need to talk to Aaron B., but if you decide to go with the mod. bit. roof let me know so I can steer you in the right direction.

Basically it breaks out like this from what I’ve seen:

Aaron B. = Spray polyurethane foam and polyurea roof systems;

gtp1003 = Shingles

gweedo = Tile

dennis = Slate and metal

roofboss = Coal-tar pitch BURs

QRFL = shingles and ventilation

Cerberus (me) = Asphalt BUR & Mod. Bits.

Needless to say, everyone pretty much knows more than the systems listed above. For example, Aaron also installs mod. bits., and I’m sure roofboss does asphalt BURs as well as coal-tar pitch. But in the end, the list pretty much identifies what I’ve come to associate each poster with. So for those of you listed (Aaron), don’t get upset if you feel like I’ve pigeon-holed you into one of several categories within the roofing industry. Heck, I’ve even short-changed myself as I used to install EPDM, PVC, below-grade waterproofing, coat-tar pitch, metal, GRM, modified asphalts, etc…


#3

Wait a second i push the ventilation and taught QRFL about ventilation. But you are right dont talk to me about flats or tile.


#4

This post settles it then… My wife is right, I don’t know sh*t. :frowning:


#5

I did not realize you taught QRFL about ventilation, my bad. However, like I said, that list was based on MY observations since posting here.


#6

Thanks Cerberus,

My plan was to scrope off the old foam anyway, since all have told me that keeping it monolythic vs 2 layered is very important. So if tear off is a ‘sunk cost’ associated with a bad original foam job, then starting from scratch it sounds like your a mod bit guy. Is that nased on

A. Better water proofing with Mod Bit
B. The insulation factor is not worth going to foam
C. Lifespan of Mod Bit Torch is better
D. Other_________?
E. All of the above???

Thx!!


#7

Sorry G-tape, just because you were forgotten on my list, doesn’t mean you don’t know your sh*t. There are others here also that I’m sure I forgot. Maybe once everyone chimes in another more complete list can be made.


#8

No, no, don’t back down now Becky…er, I mean Cerberus, its much easier this way. Now nobody expects anything from me.

Look how that one guy is always asking Aaron now?! I don’t want to be tied down to knowledge.

I think Cerberus is really my wife typing from another part of the house. :?


#9

[quote=“bshnid”]Thanks Cerberus,

My plan was to scrope off the old foam anyway, since all have told me that keeping it monolythic vs 2 layered is very important. So if tear off is a ‘sunk cost’ associated with a bad original foam job, then starting from scratch it sounds like your a mod bit guy. Is that nased on

A. Better water proofing with Mod Bit
B. The insulation factor is not worth going to foam
C. Lifespan of Mod Bit Torch is better
D. Other_________?
E. All of the above???

Thx!![/quote]

With regard to line item “A,” yes, I believe it is a better waterproofing membrane. SPF (spray polyurethane foam) is a cellular system that relies heavily on a coating that is applied over the SPF. A good modified bitumen system consists of several layers of asphalt and/or modified asphalt products.

SPF has a high R-value, and in my opinion is the primary benefit in using foam. However, you can achieve high R-values with roof board insulations like a polyisocyanurate. So, with regard to “B,” either roof system is an option.

With regard to line item “C,” yes, if both systems were left unattended and not maintained the mod. bit. would outlast the SPF. However, it is always advisable to maintain your roof since it is the most important part of your structure. SPF and mod. bit. roofs can be long lasting if maintained and ocassionally coated/recoated. SPFs have sustainable systems, i.e., you can keep recovering the original application and buy more warranty time with each application. There are only a few mod. bit. manufacturers that I know of that will do this by allowing you to add an additional layer of membrane. However, you can always install a venting base sheet and additional membrane over the existing system when it is time to replace the roof. As far as life-span, I suspect you would get around 15-20 years out of a mod. bit. system in your region, but you could probably bump that up to 20-25 years if you coat the mod. bit. after years 12-15 or once the membrane has begun to loose granules. So, compare that to how ever long you’ve had your SPF system without any leak problems.

To address line item “D,” the primary thing there is the mod. bit. will take more abuse than an SPF. For example, dropping an HVAC unit access panel on the mod. bit. may gouge the membrane, but will probably not puncture the membrane. On an SPF membrane, you would likely penetrate the coating that keeps the SPF watertight.


Now, with regard to how to install the new roof system, you will want to do a few things to ensure you get a “bulletproof” roof. You want to install multiple plies of modified bitumen or multiple plies of asphalt built-up roof with a modified bitumen cap sheet. I personally prefer a 3-ply built-up roof with a granule-surfaced APP modified bitumen cap sheet. Base flashings should consist of a smooth-surfaced mod. bit. and a granule-surfaced mod. bit. If you give me more information, I can better help you out, i.e., wood roof deck? parapets? HVAC units on roof? skylights? gutter or drains? etc…


#10

[quote=“G-Tape”]No, no, don’t back down now Becky…er, I mean Cerberus, its much easier this way. Now nobody expects anything from me.

Look how that one guy is always asking Aaron now?! I don’t want to be tied down to knowledge.

I think Cerberus is really my wife typing from another part of the house. :?[/quote]

:lol:

Actually, we all fear your knowledge and we don’t like the competition! :mrgreen:


#11

Although I do both,

SPF, if properly installed, has an indefinite lifecycle. Depending on the membrane/coating, SPF will outlast modified bitumen after the initial install for who knows how long. The Superdome had numerous bullet holes through the original SPF roof before they re-rofed it in EPDM, and it never leaked.

Scarfing alone may not be the way to go. Any blisters should be removed, as well as moisture trapped in the assembly, and re-foamed. You most likely will not even need a whole new roof.

I would find an EXPERIENCED SPF installer and ask for the foam roof and an aluminum polyurea topcoat. You will be glad. DO YOUR HOMEWORK on the installer. HE is essentially a manufacturer, processing semi-raw materials to produce the finished product.

Your blistering is not from a poor mix. It is from spraying over moisture. If it was a poor mix, the reaction would not have completed, and you would not get foam.


#12

stupid ass G,
lol.
and how di i end up tile.
i hate tile.
i was thinkin more like roofing god of souteastern united states.
hello bshnid,
i have to disagree with mr cerberus on this one, which i think is a first.
even though i do support the evolution of foam roofs and there coatings. im a fan of torchdown cause of what ive seen it do and you can always foam over it 10 or 20 yrs from now.

good luck.

gweedo


#13

OK darn it!!!

I think I have more EPDM experience than anybody here !!! Plus my shingle experience puts me up at the top also.

Then with my roof repair business, I see all the problems with all the different roofs out on the market!!!

I’m going to have to say that I am smarter than anybody here, sorry guys 8)


#14

as of nov 1 we will have installed 97k sq of epdm,22k sq of tpo and roughly 17k sq of modified,1.5k sq ctp. since jan4 think you know about rubber show me some tricks.


#15

A renaissance man.

roofboss, how does all that work count at the end?


#16

Talk about a bunch of wadded up panties and ruffled feathers! :lol:

Alright, why doesn’t everyone just list the TWO (2) systems they feel they qualify as being “experts.” Limit it to only two, because trust me as a consultant I too can list several systems. As a roofer I probably put down more EPDM than anything, followed up by asphalt and coal-tar pitch BURs, but as time has gone by I’ve learned more about mod. bits. So, I’d have to say I know more about mod. bits. and asphalt BURs than any other system at this time. It is what I specify and inspect on a daily basis, although I survey all types of roofs and see the short-comings of most.


#17

take galvalume on slopes torchdown on flats and call in 20+ years.

gweedo.


#18

Thanks again all.
To answer some of the clarification questions you asked:

  1. Wood roof deck? Yes
  2. parapets? yes (surrounding all 2300 sft. - 3 feet high)
  3. HVAC units on roof? yes 2 large units
  4. skylights? No, but a 2x2 alum. hatch that accesses the attic from the roof (a source of leaking in the past). One vent for watercloset.
  5. Gutter or drains? just 2 Scuppers at N/E and N/W ends of slight pitch
  6. Other? A 12x12 view/walkdeck made of 2x4s and plywood covered with elastomeric (i’ve been told to foam over it as part of the overall refoam and then set a free floating deck on top to avoid penetrating the foam, using trex or something similar)

Finding a “qualified” foam roofer in Phoenix has been hard. Most are new. many seem to know less than I do, based on their response to basic questions, like can we foam in 50 or less degree temps, or f the foam insulation difference pays for itself.

Even after your valuable information, I’m torn on Torch vs Foam. Lots of research, still seems down to a coin and luck, luck finding a good foamer, and a coin to see if the foam outlasts and outperforms mod bit torch.

Maybe i should consider the Panties and Feathers idea…


#19

Check this out.

http://www.polythane.com/library/index.htm


#20

Thx. Found this there…

"new Life Cycle Cost Analysis of SPF roofing systems shows in most situations, SPF roofing systems have a lower 30-year Life Cycle Cost than membrane roof systems. The study performed by Michelson Technologies was conducted in accordance with ASTM E-917, “Standard Practice for Measuring Life-Cycle Costs of Buildings and Building Systems.”

According to Ted Michelson, “The 30 year study period shows Spray Polyurethane Foam (SPF) having a cost advantage over membrane roofs from a low of 13% up to 56% based on the national numbers.” The lowest cost difference assumes a re-coating schedule of every 6 years and the 56% cost difference assumes a re-coating schedule of every 15 years."


Anyone think this is bogus? I’m leaning to foam.

Now if i can just find a GOOD Foamer.