| Author |
Message |
Don Harris CSI, CCS, CCCA, AIA
Senior Member
Username: don_harris
Post Number: 283
Registered: 03-2003
| | Posted on Wednesday, April 08, 2015 - 11:33 am: |    |
A similar discussion was held here:
http://discus.4specs.com/discus/messages/23/7567.html
MasterSpec has 2 sections "Hot Fluid-Applied Rubberized Asphalt Waterproofing" (with pedestal pavers, etc.) and "Fluid-Applied Protected Membrane Roofing" (with ballast pavers and aggregate ballast), which includes hot and cold applied. For purposes of this discussion let's ignore cold applied.
Is there anything specific that differentiates when to use waterproofing or roofing? I have even had one client that wanted both sections, the roofing for the top of the building and the waterproofing for the plaza deck (over parking) and lower "roofs" that are vegetated and public. If a surface is horizontal, open to the exterior, keeps out weather and covers space that needs to be protected, either living or parking, it seems like it is a roof, no matter whether it is 100 feet in the air or at ground level. Both sections contain the same "black gunk." It's what goes on top that is different. It seems like it all could be covered in one section efficiently (which is what I usually do, right or wrong). Are there different warranty issues? Does it really matter what it is called, as long as it is coordinated with the drawings? |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 816
Registered: 05-2004
| | Posted on Wednesday, April 08, 2015 - 11:39 am: | |
I have felt for a number of year that there are more than semantic differences in waterproofing and roofing. Both are installed to keep water out of a building. Roofing systems, however, are also intended to resist the effects of extreme temperature differences, ultraviolet radiation, hail, and wind uplift. Waterproofing does not bear the burden of being exposed to the elements. |
anon (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, April 08, 2015 - 11:52 am: | |
There is a difference. I have found ASTM D1079 helpful/useful in understanding the differnces, and this excellent RCI article available online:
http://www.rci-online.org/interface/2008-06-henshell.pdf |
Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP
Senior Member
Username: specman
Post Number: 1296
Registered: 03-2003
| | Posted on Wednesday, April 08, 2015 - 12:02 pm: | |
My perspective:
All waterproofing could be roofing (i.e. proper protection from UV, traffic, etc.), but not all roofing could be waterproofing (e.g. asphalt shingles, some types of metal roofing, etc.)
Ron Geren, FCSI, AIA, CCS, CCCA, SCIP
www.specsandcodes.com |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 891
Registered: 12-2006
| | Posted on Wednesday, April 08, 2015 - 01:26 pm: | |
Neat article anon.
I don't have a copy of the most recent NRCA Manual available but there was a time when roofing was defined as an assembly utilizing a membrane that protected the building and that was able to withstand heat, UV, water, freeze/thaw and similar conditions. Roofing systems, by Code, have a minimum slope of 1/4 inch per foot.
In the Fifth edition of the NRCA Manual (before there was a separate Manual of Waterproofing) waterproofing was "defined as the treatment of a surface or structure to prevent the passage of water under hydrostatic pressure." Waterproofing was expected to "protect floors and walls below grade", "protect spaces beneath roof systems and plaza decks", "isolate wet spaces such as kitchens, showers,..." and essentially "keep water from leaking".
Waterproofing was expected to "Perform for an extended period of time, preferably for the life of the structure." It was expected to "Perform successfully in a constantly wet environment..." as well as resist environmental contaminants and construction activities since it must remain in place and intact during backfilling or until a protective wear course could be applied.
In terms of design, waterproofing had to accommodate anticipated structural movement but was not expected to withstand the excessive thermal stresses, temperature fluctuations, or UV radiation that roofing had to be able to withstand. Most waterproofing was to "have the advantage of being adhered directly to the structural substrate" and protected from physical abuse.
Horizontal deck waterproofing was allowed to be dead flat and was expected to withstand ponding water. Using the term waterproofing presumably allowed placement of a PRMA type application on a zero-slope deck with insulation above the membrane (plus over-burden). The argument was that this was no longer a roofing application and therefore did not have to comply with the Code-imposed 1/4 inch per foot slope rule. Apparently Code officials all over the country agreed since hot-rubberized asphalt membranes have enjoyed a nation-wide popularity for decades. Now with restrictions on cookers (melters, kettles, etc.), hot-fluid-applied membranes are becoming more difficult to use. |
Don Harris CSI, CCS, CCCA, AIA
Senior Member
Username: don_harris
Post Number: 284
Registered: 03-2003
| | Posted on Wednesday, April 08, 2015 - 02:49 pm: | |
Thank you all for the input. Good article. At least now I'm caught up after 7 years. I'm thinking now a "one size fits all" waterproofing section with a system warranty is probably the way to go. Of course there will always be other sections i.e. wood decking, masonry walls, etc. Ron you kind of confirmed what I was thinking about all waterproofing being roofing. I'm still not getting why a kettle is a problem on a concrete framed structure, but what do I know? Thanks again. |
anon (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, April 08, 2015 - 04:01 pm: | |
there is a longstanding code exception to the 1/4 inch in 12 slope minimum for coal-tar built-up roofing systems, which the IBC allows to be installed to a 1/8 inch per 12 slope.
This is something I discovered years ago, found quite interesting, and use it from time to time to befuddle architects and enclosure consultants that insist all roofing must be minimum 1/4 inch per foot slope. I also like to use this little nugget when making the argument that hot rubberized asphalt can be applied at a dead flat slope. |
Alan Mays, AIA
Senior Member
Username: amays
Post Number: 211
Registered: 02-2003
| | Posted on Wednesday, April 08, 2015 - 06:49 pm: | |
Ken, The issue to me is what is considered a roof? Code seems to be very gray. What we used to call plaza deck waterproofing was an occupied space. You could have a flat surface and waterproofed it. Today, AHJs sometimes allow that and others say it is still a roof. There is no real clear definition in the code book. The slope issue in the code requires that there be positive slope to allow water to drain in 48 hours. Again that is found in the definitions and not in the actual roofing chapter. The definition for a roof deck is a cover that provides shelter, flat or sloped. The definitions muddy the water. Is an exterior occupied space considered a roof? If so, then by definition it must provide positive drainage per the definition. This is another good example of how the code is screwy. Way too gray and it needs more clarity. |
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