Mod-Bit Roofing

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Author Message Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 75 Registered: 11-2003 Posted on Friday, March 02, 2007 - 09:14 am:    I need your advice. (South Florida application) I'm getting lots of conflicting input from roofers, Reps, and the like about when to use APP & SBS polymer modifiers and when to use glass fiber & polyester reinforcements. APP vs SBS Modified Polymers: Rule of thumb used to be to use APP for torch and SBS for hot asphalt mop applications...but I'm now being told by vendors (some who don't make APP) that's old thinking and SBS is the preferred way to go for torch application. Glass vs Polyester Reinforcement: I'm hearing from Reps that glass is best for hot asphalt and polyester is best for torch applications. Can anyone confirm or advise? David R. Combs, CSI, CCS, CCCA Senior Member Username: davidcombs Post Number: 204 Registered: 08-2004 Posted on Friday, March 02, 2007 - 11:04 am:    Russell, Just finished a spec for a large hospital project in Fort Myers. We specified a torch-applied SBS-modified, with non-woven polyester mat reinforcing. Job went out last May, '06, was put on hold for a short time, then the project was sold, and is now going full tilt. I have heard of no problems from the CA or design team, nor from the construction team who are usually the first to balk if they think something has been specified incorrectly (in hopes of promulgating a change order). So we either did something right, or no one's caught it yet. <grin> Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 328 Registered: 05-2003 Posted on Friday, March 02, 2007 - 02:25 pm:    Russell What I have been told by several SFL roofers is that SBS is too soft in SFL heat and walking on the membrane will force the ceramic granules into the softened bitumen adhesive. If you go up on a SBS roof that is a couple of years old, the walked on surfaces are clearly visible with the asphalt alligatoring on the surface, so APP adds some longevity to our hot roofs. For most of our SFL projects we spec APP unless SBS is requested by Architect/Owner. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 329 Registered: 05-2003 Posted on Friday, March 02, 2007 - 02:27 pm:    David I wonder if Crowther Roofing is doing your project? if they are consider yourself fortunate, they are one of the better roofers in Ft Myers. Wayne Yancey Senior Member Username: wyancey Post Number: 299 Registered: 05-2005 Posted on Friday, March 02, 2007 - 02:40 pm:    Russel, I work in the PNW where the temperatures are cooler year round than south Florida. SBS is the first product of choice in my region for its superior properties in colder (heating) climates. SBS increases flexibility over a wider temperature range than APP (PNW experienced ambient temperatures in the 90s in summer). SBS-modified asphalt has excellent elongation and recovery properties and remains flexible at temperatures below minus 10 deg F. Adding SBS polymer to asphalt flux can increase the softening point from approximately 90 to 260 deg F. APP was our first product of choice in warm (cooling) climates such as Pheonix because of it's higher softening point. The thermoplastic nature of the modifier increases the softening point of an asphalt from 90 to 300 deg F. APP imparts good weatherability and resistance to UV exposure to the product, and the toughness of APP can provide the product with more tensile strength, depending on the roof temperature. That said, I have been involved in a project that went from SBS to APP for a cost savings the Owner could not refuse. We avoid hot asphalt applications for obvious reasons plus many of our projects are high-rise or mid-rise. Wayne Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 331 Registered: 05-2003 Posted on Friday, March 02, 2007 - 03:03 pm:    Russell, you may want to call Karen Warseck at Building Diagnostics Associates located in Hollywood, FL, I consider her an expect in SFLA roofing applications, she is an Architect who concentrates her practice on roofing and cladding issues; I've learned alot from her over the years. Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 76 Registered: 11-2003 Posted on Friday, March 02, 2007 - 04:25 pm:    Jerry, I just got off the phone with Karen Warseck. Thanks for the referral. You're right, Karen is very knowledgable and helpful. She confirmed a lot of what I thought I know and then some. Problem is, I'm still getting a different versions from the mfr's I'm being asked to specify. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 332 Registered: 05-2003 Posted on Friday, March 02, 2007 - 06:55 pm:    Russell - which manufacturer? Joanne Rodriguez, CSI, CDT, LEED AP Senior Member Username: joanne Post Number: 48 Registered: 09-2004 Posted on Sunday, March 04, 2007 - 10:25 pm:    I can tell you that torching SBS--which is rubber--is a dicey proposition. It has a much lower softening point than APP--which is plastic. There is a good chance that over heating the SBS membrane can create issues of adhesion, similar to that of "fallback" with regard to EVT's. We have been experiencing SBS installed in hot and/or cold, with the lap seams being torched for a cleaner appearance. The reason contractors like APP and frequently substitute it is due to the gain in production. It is a much quicker installation without having to worry about over-heating. The problem with APP installations is inexperienced contractors with torches. You will want to specify a fire watch and proof of training according to NRCA Certa program. Canada has outlawed this means of application and underwriters are raising premiums here in the states. With regard to the carriers--polyester v. glass. Polyester is durable but lends properties of movement, whereas glass is more durable but lacks the movement properties. You could always consider a composite--polyester and glass sheet--if you aren't sure what you need. I personally think that an APP sheet with a glass carrier or composite carrier makes sense because by default you are not specifying a sheet with strong movement capabilities. If you need some "self-healing" properties then you should use SBS and if you have high movement then you will need SBS with polyester. I am not in Southern Florida but can recommend others who work in the area if you are still stymied by the issue. Just make sure that you are getting the right substitution. Just a question back to you, why change your original spec if you were comfortable with it at the time? You should not be overly concerned with the cost savings measures of the contractor. They generally do not pass these savings along to anyone else. Good luck! Richard L Matteo, AIA, CSI, CCS Senior Member Username: rlmat Post Number: 199 Registered: 10-2003 Posted on Monday, March 05, 2007 - 12:43 pm:    When I was working on the East Coast, most of my roofing people were recommending SBS either hot-mopped ot torch-applied. Projects were in Chicago & Denver. Here in So Cal, at my firm,we have stopped the use of torch-applied membranes, mostly because of fire hazard, especially on wood framed buildings, and insurance regulations - many of the roofing contractors out here balk at torch application, especially during wildfire season! We are currently specifying cold-adhesive applied systems. Wayne Yancey Senior Member Username: wyancey Post Number: 303 Registered: 05-2005 Posted on Monday, March 05, 2007 - 12:47 pm:    Being an ex-pat Canadian (or Resident Alien and Permanent Resident) I became curious regarding the above statement "Canada has outlawed this means of application..." I inquired with several Canadian (Alberta) contacts. Albertan 1: Personally, I have not seen an outright ban by any authority having jurisdiction. BUT, I have seen a pronounced preference with design consultants to not use (specify) that category of products. I am still specifying SBS but at the specific request of my design consultant clients. Albertan 2: There is not a ban on torch applied roofing materials, but the insurance premiums resulting from using torch applied systems tends to make these products less competitive now than some of the other membrane types that we have available. We have specified cold applied SBS, but these are still pretty expensive, so only when the client specifically requests. I would estimate that about 40% of all our roofing specs are still based on torch applied SBS, as well as about 80% of our air/vapour membranes. Peel and stick just does not perform well in our part of the world, so I think you will still see torch applied membranes for several years yet. The insurance situation appeared after a couple of very controversial fires in Alberta, none of which was started by roofers, but which cost the insurance companies several 100's of millions of dollars. So any one using open flame or propane on the job site got tarred (sic) with the same roofing mop. There have been fires started by roofers, more recently the total emollition of a historic building in central Alberta, but the increase in rates is largely spread across the entire construction industry. There are general contractors who will not permit torch applied SBS on their projects, but I think you will find that these particular builders are of the "cheap and nasty" ilk. There is a trend towards single ply PVC and TPO, but I think we are a long way off from having these membranes supplant the SBS market. Albertan 3: It is news to me if torch applied membranes have been banned in Canada. I have a call in to ARCA to find out what they know. Earlton fire was caused by torch applied waterproofing not roofing, but there was at least one other fire in Calgary that was roofing. Wayne EH! Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 77 Registered: 11-2003 Posted on Monday, March 05, 2007 - 02:18 pm:    Jerry, We've been asked to specify GAF, Firestone, Manville, Siplast, & Soprema by our Roof Committee (comprised of Archs, Engs, Maintenance Dept, Owner's in-house roof Guru, & several roof-subs. However, these Mfr's don't all make the same product; those that make APP say use it for torch, those that don't say SBS is just as good for torch. Some make glass, poly, & glass/poly reinforcement, while some only make glass. Some (Siplast) say the interply membrane should be thicker than the cap sheet, while others disagree. Joanne, I am re-tooling our spec (specs I inherited) because it hasn't been updated in 5-6 years plus it was written around very expensive roofing Mfr's products that our Roof Committee no longer feels is worth the bucks. Joanne Rodriguez, CSI, CDT, LEED AP Senior Member Username: joanne Post Number: 49 Registered: 09-2004 Posted on Monday, March 05, 2007 - 09:40 pm:    Russell, I think the pressing issue will be to choose one or the other for that specific application. You will have a really difficult time trying to incorporate APP and SBS into the same specs as the properties are inherently different. Have you considered developing two specs? Then with the individual specs you can develop system performance criteria which lends itself to multiple manufacturers competing. You are then setting the performance standard and minimum criteria such as # of plies, etc. Approaching the representative specifications in this manner will allow you to adequately specify to the properties based on need and you will not be trying to match everyone's sheets to your spec. A system tensile/performance standard ASTM 2523 is a much more straight line method of specifying and it levels the field--all manufacturers can compete the spec. It seems that since your client is driving commodity and service is not an issue you can create a very competative bid situation. Wayne, I will pull up the information I have on the Canadians and the ban. I could be cart before the horse here, maybe it is only proposed, but I was fairly certain that it was in effect as there is much discussion within roof organizations about it. Still a good idea for all using APP torch applied--CERTA training and fire watch standards set forth by the NRCA. I can provide you with a rash of articles about fires as a result of overheating of structural elements. Wayne Yancey Senior Member Username: wyancey Post Number: 304 Registered: 05-2005 Posted on Tuesday, March 06, 2007 - 10:24 am:    Joanne, Please forward the information on the Canadian ban. I would also like to read more regarding the fires as a result of overheating of structural elements. e-mail wyancey@weberthompson.com Thanks, Wayne Steven Bruneel, AIA, CSI-CDT, LEED-AP Senior Member Username: redseca2 Post Number: 29 Registered: 12-2006 Posted on Tuesday, March 06, 2007 - 05:40 pm:    Just to get things even more confused. We just went through an in-house review with a major roof/waterproofing consultant with an emphasis on Mod Bit Roofing. Consensus recommendation: SBS Manufacturer: Siplast, Tamko, Soprema SBS 1st layer: self-adhered SBS 2nd Layer: Hot Asphalt/Torch Seams Mineral Cap Sheet Fluid applied topcoat if a "coolroof" is required. Wayne Yancey Senior Member Username: wyancey Post Number: 308 Registered: 05-2005 Posted on Tuesday, March 06, 2007 - 08:04 pm:    Our standard SBS over wood base is: Three ply consisting of base interply and cap modified membranes; heat welded (torch-applied) to mechanically attached SBS modified base sheet on wood decking. Field Self-adhesive base ply membrane flashing is self-adhesive. Chris Grimm, CSI, CCS, MAI, RLA Senior Member Username: tsugaguy Post Number: 66 Registered: 06-2005 Posted on Friday, March 16, 2007 - 10:48 am:    For those times when torching is needed, a flameless torch (e.g. Sievert) is available. We normally avoid spec'ing methods and means but perhaps it could be appropriate to keep from burning the building down during construction - especially an issue for renovations/additions of occupied buildings where the A201 Contractor's jobsite safety clause might not fully cover the health/safety/welfare of the public. Here in the Carolinas I am told APP may become too rigid during the colder months. We are about at the southern edge of SBS territory. We have been spec'ing a cold applied SBS/BUR hybrid system, possibly hot-mopped instead when the cost is a concern and there's not an issue with the hot kettle - e.g. unoccupied new concrete structure. For projects further south we might consider APP. Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 78 Registered: 11-2003 Posted on Monday, March 19, 2007 - 10:48 am:    We're leaning towards specifying a mod-bit cap sheet with a composite fiberglass/polyester reinforcement...we're told this membrane is the strongest (our system description: 1-ply felt base, 1-ply SBS interply, 1-ply SBS cap, hot asphalt or application). Please indulge me one question; would you recommend the interply sheet also be a composite fiberglass/polyester, polyester, or fiberglass reinforced? Phil Kabza Senior Member Username: phil_kabza Post Number: 238 Registered: 12-2002 Posted on Monday, March 19, 2007 - 01:53 pm:    There's debate between manufacturers concerning the best location in multi-ply systems for the majority of the tensile strength. I am inclined toward placing the greatest tensile strength at the base or interply level, where failures might otherwise remain undetected until upper plies fail. That would argue for the composite, or the fiberglass, at the bottom, with the highly flexible polyester on top, if used at all, where thermal movement would be greatest. The nature of the interply bond comes into play here: how much relative movement is absorbed across a cross-section of plies of various types? There are wide differences in the array of MB sheets available from manufacturers. Their marketing and their technical advice is typically geared toward their available sheets. Those who only manufacturer fiberglass reinforced MBs are quite passionate about why that's the only way to go. Good luck finding objective advice; even the independent roof consultants can be pretty narrowly focused on a few manufacturers. That's why I like Joanne's advice above concerning designing around cross-section performance vis-a-vis ASTM D 2523. I'd appreciate some knowledgeable follow-up comments regarding the comparative flexibility/tensile strength of the three ply types and their applicability in different climates and roofing conditions. Bob Woodburn Senior Member Username: bwoodburn Post Number: 165 Registered: 01-2005 Posted on Monday, March 19, 2007 - 03:24 pm:    Supposedly the polyester reinforcing is good because of its stretchability, and the glass fiber is good because of its strength and resistance to stretching. I never could figure out why both were used in the same membrane; one would think the glass would counteract, or restrict the stretching of, the polyester. I know of one manufacturer who makes such a composite glass/polyester reinforced mod-bit membrane (though there may be more), and I suspect that it does so for proprietary advantage -- this manufacturer likes to work directly with the Owner on re-roofing projects (with no architect involved), and prepares the specs as a free "service." Like a lot of proprietary specs, they seem to have a lot more testing requirements than necessary, which (in addition to the unusual redundant (and "counteractive") reinforcing, tends to eliminate the competition -- so while it may result in a good roof, with no interest from other bidders, there is no real competitive control on the cost, and the Owner ends up paying a lot more than it needs to. I am told that there are at least three companies that play this game. I hesitate to name them. (They are NOT, obviously, the well-known major roofing manufacturers that actively market to architects.) Presumably, they respect each other's respective "clients" out of "professional courtesy". Joanne Rodriguez, CSI, CDT, LEED AP Senior Member Username: joanne Post Number: 50 Registered: 09-2004 Posted on Monday, March 19, 2007 - 04:15 pm:    What I find interesting through this thread of conversation, coming from one of those three manufacturers who are NOT well known to architects and being a well-known architectural rep in my own right (note the irony), is that there is virtually a complete oversight of evaluating a system as a whole. You can have a decent polyester ply or cap sheet, because you have movement, but set it in a straight hot asphalt type and you have essentially negated the effect of the polyester sheet. It is not appropriate to have a conversation about roofing systems that are not inclusive of an entire "system". A roof system by my definition is one which encompasses building usage, deck type, insulation needs, ply sheets, asphalt types, flashing systems (a whole system in it's own right) and details, surfacing and last but not least maintenance considerations. I can tell you the relative differences between all of the sheets, and have in past postings on this site, but without due consideration to the system as a whole, such as rubberized or non-rubberized asphalts, you are not getting a true story. Unfortunately the MB industry, as a whole, has played a game of carriers, thickness and tensile strength without necessarily designing to the needs of the builing. Whatever happened to providing sound solutions? ASTM 2523 is the truest measure of this and was established by NIST--not a manufacturer like me. Every manufacturer's sales reps (some come in the form of roofing contractors and/or consultants) know how to play the game to their advantage--much like architectural firms do through billing or design re-use gone new. If you have an interest in non-biased information on what sheets to use where don't hesitate to contact me. It really is too much information to post and some of it has been addressed pretty adequately above. Bob the reason that you have consultative manufacturers in the marketplace is that they deliver a high-level of service to the owner and to the architect when applicable. When re-roofing considerations were not in vogue there were very few resources for owners to rely on, not to mention very few manufacturers or architects willing to take on the liability. I am glad to come from a manufacturer that works with a multitude of entites: architects, owners, consultants and contractors. It has always been my goal to work with those who are willing to work with me. If there is an architect involved in design process then they should be taken in to the process, just like the manufacturer should if that be the owner's desire. I will say, to all of you, that if your manufacturers are not working with you and the owner in tandum it can lead to more change orders, and possible issues in the end. Whenever roofing is the principle concern all entitites should be involved from the beginning. Bob Woodburn Senior Member Username: bwoodburn Post Number: 167 Registered: 01-2005 Posted on Monday, March 19, 2007 - 04:57 pm:    My remarks stemmed from experience as a spec consultant to an architect that was indeed "taken in" by the roofing manufacturer. The manufacturer's rep had been consulting with the Owner (a major municipal department), but the Owner decided it might be good to get an architect involved. They referred the architect to the roofing "consultant" without recommendation, to use or not use as it saw fit. That should have been a tip-off right there, I suppose. After the architect and I were assured by the roofing manufacturer's rep that the spec it prepared would be non-proprietary - one that any manufacturer could bid on - we were "taken in." When we later realized that anyone could indeed bid on it--as long as they were willing to produce a special, unique membrane that no one else made (that we knew of) but this one manufacturer, and were willing to pay to have a whole bunch of additional testing done, which of course none were interested in doing--we realized that we had been given a "stealth" proprietary spec. After lots of finger-pointing and jockeying for advantage by competitors and several addenda later, we came up with a spec that several manufacturers could bid on, apples-to-apples. I was later told by another manufacturer's rep (who was aware of the game being played) that the resulting competitive spec probably saved the Owner around $50,000. Joanne Rodriguez, CSI, CDT, LEED AP Senior Member Username: joanne Post Number: 52 Registered: 09-2004 Posted on Monday, March 19, 2007 - 07:18 pm:    You are right to be suspect of over involvement, but I would caution to not follow once bitten twice shy feelings. For every bushel of apples you'll find a few rotten--the same is true within every organization. Rep for rep you will find the majority who really want the best situation for the owner and who welcome the involvement of the architect. I will take this opportunity to mention, quickly as I don't think this is necessarily the right thread for this conversation, that in my years I have come across many firms who knowingly and willingly sole source manufacturers. This practice, particularly in schools and public bid arena, do not necessarily represent the best of the best either. But I have found in both instances, yours and mine, that the owner has made such request of one party or the other but is hesitant to vocalize their feelings. I think if you are comfortable with what you are specifying--whether it is one manufacturer or 10 (which is also not a desired practice)--realize that the entire system and service definitely should be discussed at all levels. Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 79 Registered: 11-2003 Posted on Tuesday, March 20, 2007 - 08:49 am:    Joanne, You mentioned above knowing others in South Florida (roof consultants?)...if you could give me contact info I'd like to speak to them.