[RoofPro]

MARS Bar

That’s right – MARS Bar. Only one I ever saw that worked was on a barrel roof. I guess with enough slope anything will keep the water out. On a low slope roof candy bars may have worked just as well.

 

[RoofPro]

Mars

RooferJim
The Carlisle system you were referring to was called MARS NP (Mechanaily Attached Roofing System Non-Penetrating). As some of the other posts have described a special base plate was installed under the membrane. A white retainer piece snapped over the membrane onto base plat pinching the membrane, then a cover plate screwed over the retainer. I was a Tec Rep for Carlisle in the 80’s – I thought this was a marvelous bit if engineering, until we learned the retainers were not only pinching the membrane but also poking holes in it. Still it was an improvement on Carlisle’s original MARS – A batten bar set in a bed of Water Cut Off Mastic and fastened through the membrane – no cover strip over the bar.

I know of one MARS – NP that’s still in service. Has to be 25 years old and ponds about a 1” of water over 40% of the roof. The owner told me about a year ago it leaks once in while, but only when the roof is covered with deep snow and a thaw occurs.

 

[RoofPro]

You've stuck gold Outlaw - Im sure I don't need to tell you, but treat that job like your doing your mom's roof.

 

[RoofPro]

Reply to original question

If your looking for a roof that will last, won’t leak and will put up with a lot of abuse its hard to beat a 4 (or 5) ply gravel surface Built Up Roof. Asphalt is good, coal tar is even better. (RooferJim – are you really nostalgic for that stuff? Man – just thinking about it makes my eyes burn ☺.)

SBS modified is ok – but defiantly more prone to problems – wrinkles, cap sheet granule loss, blisters.

I like single plys a lot, but only when the roof is not subject to foot traffic and other abuse. EPDMs been around since the 60’s and since the manufacturers switched from glue to tape at the seams they have performed exceptionally well. I also like the fact that any tool you need to install EPDM can be found at the neighborhood hardware store
I also like PVC – hard to beat a good heat welded seam. Unfortunately I’ve inspected a number of jobs where the welds are not good. Still if you need a reflective roof PVC is the way to go.

Not a big fan of TPO, it’s a relative newcomer to the US market and the manufacturer’s are still playing with the formula, trying to balance the need to meet UL and FM requirements for fire resistance with the need for a roof that will hold up to UV light. Last year at the NRCA technical committee reported problems with TPO membrane surface cracking along the backside of seams along with other problems. I agree with SinglePlyGuy – need to see more of a good track record before I’d recommend TPO.