Cutting Corners and Falling Through the Cracks
By Jeannine Patané • April 2005

     If you are a master at lining shelves with contact paper or you know the art of toasting marshmallows, and you’re ready for more worldly projects, try roofing your house with thermoplastic polyolefin (TPO). I don’t want to make membrane application sound easier than it is; it just takes some patience and finesse to transfer shelf lining and marshmallow toasting skills to your roof. Keep in mind however, improper TPO adhesion can cause frustrations, delays and waste, and exposed TPO adhesive can even cause a fatality, as it did on our job site. Let me explain further.
     Tom needed a new roof and Keith was excited to take on the project. With a Dallas phonebook between their greasy restaurant plates and coffee cups, they scanned the yellow pages for the closest roofing supplier to the downtown restaurant and called the number to see if the supplier was open for business. When they received an answer, they tipped the surly waitress and headed out the door.
     Tom described his problematic flat roof to Greg, the owner of the roofing supply business, and Greg immediately talked Tom out of using conventional bitumen materials by introducing him to TPO. Both Tom and Keith were sold. Greg was elated to see residential use of TPO, because he almost always sees it used commercially, such as the TPO application on the marquee-like Denver International Airport. He offered his knowledge, equipment and assistance to help us through the process. When the guys returned back to the house, all I knew was we were going to put on some kind of “alternative” roofing system. I had no idea what was to come.
     It took the three of us, along with seven Spanish speaking day-laborers, to strip off the badly patched standing seam metal roof and fill a 30-yard dumpster. We had a lot of cleanup and substrate patchwork to do. As artists see it, we were prepping the canvas for the medium. Then Greg showed up with a rented trailer and all of our paper, TPO, termination bar, pipe boots and corner flashing. He even loaned us his roller and hot air welder for seam sealing. Greg said he would return after we complete the job to check our seam work.
     TPO is self-adhesive; it looks like giant rolls of contact paper and is applied in a similar manner. You try to avoid bubbles and folding, and it’s a one-shot deal with full adhesion. The easier the transitions are sculpted with the substrate, the easier it is to achieve a smooth look and good seaming. A 3-inch minimum overlap gets folded onto the fascia around the roof. We left a few initial corners unfinished to figure out good termination, and because of this, we had a fatality.
     When we got to a roof corner, we didn’t adhere the TPO and just left it hanging like a tablecloth off the corner of a table, so we could take some time to figure out how to best terminate the corners. When we finally figured out a good way, I went back to finish all the uncut corners. Slicing a corner open, I was aghast to what I saw. It was a large gecko, perfectly and fully stuck to the TPO adhesive. It had to have jumped onto the membrane, because TPO is so sticky, it couldn’t have crawled that far onto the sheet. I thought about David Letterman’s Velcro wall, and a guy in a Velcro suit that springboards himself onto the wall. Yeesh. My dilemma—how do I get the poor soul off of the TPO to finish the corner?
     “Keith!” I shouted. Keith came over and his stomach was as unsettled as mine. To scrape the gecko off would mean scraping blood, flesh and guts everywhere while it all stuck to the membrane. Keith began scraping and I couldn’t watch. He quickly got too grossed out to continue. I suggested just cutting the surrounding area out, and then I’ll deal with patching over it. Keith squeamishly did the deed and I thanked him. The gecko’s tail was still hanging out when I went to finish the corner, so I swiftly ran my utility knife over it and shivered.
     When giving Tom the sad news of the gecko, he responded, “What a way to go.” Tom is aware of how sticky the adhesive is, both on the membrane and on the pipe boots. Before the boots were adhered, he was putting them on his head and reliving 1980’s DEVO music videos. He also tried hot air welding the seams of the TPO. I compared welding seams to toasting marshmallows. The membrane should get hot enough to soften and melt the adhesive, but there’s a fine line between just enough heat and melting the membrane. We took our time to practice the art of membrane cooking.
     Hopefully the TPO will last longer then the memories of our trial-and-error experiences. There’s something fun about a white membrane roof. Tom was inspired to do a Yup’ik dance on his roof, because it reminded him of a tundra landscape. After a rain, I walked barefoot on the roof and felt a strong deja vu of my time on yacht decks. The other night we had a full moon, and being up on the rooftop felt like a moonscape, with the pipe boots and vent caps resembling miniature UFOs. This white membrane covering is energy-star rated, low maintenance, and cleaner and longer lasting than traditional bitumen roofs. It’s a serendipitous inspiration and a stage for the world we live and toast marshmallows in.