SIngle ply Dibiten system vs 2 ply APP torch system??
I need advice for a flat roof that I re-framed to put 8" of pitch over 19ft into. I've been told that a single ply (base sheet, granulated cap) Dibiten system is better and last as long or longer than a 2 ply APP torch system (base sheet, smooth, granulated cap). I know that Dibiten is ALSO a torch down system! In my opinion, I would rather spend a little extra money and over kill it , rather than under kill and go with mininums. I live in Southern California, so ice and snow are NOT a problem!!!! But I do not want to mess with this roof for at least 20 -30 yrs!!! Please. NO advice to go with a BUR (hot mop), PVC, or self sealing type system, I don't think thats going to work for me. So what do the experts think??? Oh, what is the best base for this?? I've been told 25lb, 40lb, 75lb and lay fast or similar type under layment of an SBS type nature. Most guys in my area are going with 25lb. I appreciate all opinions and advice!!
Here in Florida they usually use a 75 lb. glass base sheet under Modifieds. They also have modified base sheets.
Just remember when using the torch, to get a good even bleed out of the modified especially on the ends. Don't hold the torch too close to the roll either as you will melt away your protection. Butter the ends using a trowel to make sure there are no voids or fish mouths and that the ends are flat and sealed. Be careful with using the torch on a wood substrate and use good safety practices...you are working with fire. Besides the torch method...there is an SBS Modified that can be applied using a cold process method. You have to use a modified bitumen adhesive not one made for asphalt products.
Modified's are a great product!! You've made a great choice. They are durable, the SBS product heals itself, pretty much maintenance free if using a granulated product. If going with smooth surfaced product, it is recommended to apply aluminum roof COATING (fibered) not paint for the initial coating. Then for maintenance, you can use aluminum paint. You can also use elastomeric paints as a coating too. White being the most popular color for it's reflective qualities.
Last edited by Horseygirl; 09-25-2011 at 12:50 AM.