As an in-house technical roofing resource, I receive the question, “How can I get the best roofing system for the budget I have?” on a regular basis. The question may not be stated that way, but ultimately every consumer has an obligation to do their research and determine the best value for their buck. Below is a typical Q&A that occurs when I speak with customers and prospective customers about their roofing options.Q: My contractor is removing the existing asphaltic roof system but can or should I leave the existing insulation?
A: Sure, provided that the insulation is sound, dry and able to support the new roof system. This saves on removal and disposal costs as well as providing continuing R-value to your facility. Be aware, that removal of the existing asphaltic roof system will damage the top surface, but if you expect to add additional insulation, it should be possible to overly the old insulation with new.
Q: Am I required to add additional insulation?
A: Your local code will determine the amount of additional insulation that will be required. As an example, assuming that your local code requires a total R-value of 38 and the three inches of insulation currently in place has an R-value of 15, the addition of new insulation will need to be a minimum R of 23 which equates to an additional 4.6 inches of insulation.
Q: Wow, I didn’t realize that much insulation is required. What else should I think about regarding insulation?
A: Since you called FiberTite, the roof system will have a 30-plus year lifespan, given the building information you have provided. Now is the time to think about the energy cost in 2050; do you want to use extra insulation now to hedge against rising energy costs?
Q: I see in your literature that you have 36, 45, 50 and 60 mil products. Which one should I use?
A: Membrane thickness is measured in mils. One mil is equal to 0.001 (1/1000) inches. As a reference, typical copier paper is 4 mils and card stock is just less than 10 mils thick. So, the true difference between a 36 mil and a 45 mil membrane is a piece of cardstock (9 mils) while the difference between a 45 mil and a 60 mil membrane is four pieces of paper (15 mils). However, most membranes are manufactured with a balance of compound above and below the reinforcement, resulting in a difference of one piece of paper below and two pieces of paper on the weather resistant side of the membrane.
Q: So the only difference between membranes is the thickness? Is it wise to pay X% greater for a piece of paper or two?
A: Yes and no. Yes, if the only difference between the membranes is the thickness and no if the internal reinforcement is enhanced from one membrane to the other. If the tensile, tear and puncture type physical properties remain the same and only the thickness varies, then yes you are paying X% more for the additional coating compound only. If the tensile, tear and puncture type physical properties improve by say, 30%, then your X% is for the increase in physical properties, and if applicable, the increase in thickness. For example, FiberTite offers three different reinforcement platforms, each with separate and individual physical properties. Our base reinforcement is used in our 36 and 45 mil products, while the 50 and 60 mil XT product lines provide a 30% plus increase in the physical properties. For extreme environments, our 60 mil XTreme product jumps those physicals even higher.
Q: Do you have any other advice for me?
A: If we use the 4.6” insulation thickness as a guide and $2.00 per inch of installed insulation, your below membrane investment is approximately $9 per sq.ft. A good steward of money will not allow a membrane without proven in-situ performance of 35-plus years to be installed.
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Contact our Technical Department or local FiberTite rep for assistance with any questions you have specific to your roof.