# Dow IRMA or PMR (Inverted Roof Membrane Assembly or Protected Membrane Roof) Repair



## ctc1111 (Apr 28, 2014)

Hello, I am the manager for a family owned office building which has an old Dow Chemical IRMA (Inverted Roof Membrane Assembly) or as others call it a PMR (Protected Membrane Roof). My grandfather had the roof installed in the early 70s and to this day it is doing pretty good. 

However we have some repairs to do at this point, mostly around flashing points and penetrations. There is unfortunately one field area (200-500 sq feet) that will need replacement/repair though.

I am here because I am looking for information on specifically the materials I should use to achieve the proper built up roof membrane for this application. Obviously I will want the adhesive to be a cold applied product as we are not equipped to deal with hot asphalt.

Dow has discontinued this roofing system, and will not provide me any of the original specifications for it. 

Also for perspective of our capabilities, we do 100% of our maintenance and build out work in house. We do hold contractors licenses, and are very capable. We have not been able to find a single contractor who even knows what a IRMA/PMR roof is, so we have determined the repairs will be performed by our maintenance team. 

Thank you for any input on material selections for this project. There doesn't seem to be that much, if any, info out there on PMR systems.


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## 1985gt (Dec 21, 2010)

Quick google search of IRMA roofs and I found this. http://building.dow.com/na/en/applications/building/rca/pmr.htm

Remove the rock, and insulation and repair it like you would any asphalt roof system. Replace insulation and rock after a nice long rain to check your repairs, or use a hose. Be ready for the insulation to be stuck and needing to be persuaded to come free. Might not hurt to have a few sheets of 1.5" XPS around, a lot of the insulation breaks coming up.


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## shazapple (Dec 3, 2010)

Any inverted roof I've come across are great with little maintenance... until they are over 30 years old. After that, you start having issues and the membrane starts failing throughout. If it's EPDM then you'll have splits and stretching. If it's felt and asphalt then the insulation is probably stuck to the membrane, which will tear when you pull up the insulation. 

In my area, a 40 year old inverted roof is a ticking time bomb.


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