| Author |
Message |
Brian Payne, AIA
Senior Member
Username: brian_payne
Post Number: 47
Registered: 01-2014
| | Posted on Monday, July 28, 2014 - 05:05 pm: |    |
Any one have any thoughts on using the singly ply manufacturer's standard detail for a roof expansion joints. Personally it reminds me of a "pool noodle" burrito. I have always preferred either the bellow or metal plate style manufactured product, but I honestly don't have any good justification for my preference. |
John McGrann
Senior Member
Username: jmcgrann
Post Number: 122
Registered: 03-2002
| | Posted on Tuesday, July 29, 2014 - 07:54 am: | |
The primary advantage to using the membrane manufacturer's detail is their "total systems" warranty coverage should include the expansion joint. The other types of joints would typically be excluded from the roofing system warranty.
The other types of joints are probably more appropriate for wider joints or where there's an expectation for a greater degree of joint movement than would be accommodated by the membrane manufacturer's detailing. Movement parallel to the joint can be problematic for either the membrane or bellows type of joints. Properly engineered and selected metal joint covers seem better able to handle parallel joint movement.
Regardless of joint type selected, detailing at the ends of the joint at transitions to walls or parapets for all types can be problematic. Those transitions are where we see many problems.
John T. McGrann, Jr., AIA, CSI, CCS, LEED AP
|
spiper (Unregistered Guest)
Unregistered guest
| | Posted on Tuesday, July 29, 2014 - 10:03 am: | |
I also do not have any good justifications for my preferences other than positive experiences. That being said we have always used the Expand-o-flash type expansion joints at most major locations. We have in some situations used the foam rope expansion where the roof meets a vertical wall as long as both the roof and wall were constructed at the same time without an expansion joint in the structure.
In very large roof areas or at building expansion points, additions, etc. we will split up the areas with prefabricated curbs (Pate, Thycurb or similar) and then put the expand-o-flash type cover on top of the curbs. We used to utilize treated lumber for the curbs but the lumber tended to twist, warp, etc. so by the time you had to re-roof, or maybe even before, the curb was shot. The prefabricated curbs can last for several decades.
We have never had any push back from membrane manufacturers in terms of warranty issues. We also use the curbs at times when we have to make a break in the roof system. If a client can only budget so much money per year for reroofing we can use the curbs to split one warranty area from another. Using a rope expansion at such transitions leads to issues in our experience.
It should be noted that most of our business is repeat work for institutional clients so long term benefits are given more consideration. If you are doing big box stores the extra initial expense for the curb and bellows may make it difficult to show a reasonable ROI. |
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