Making sense of roofing proposals from different contractors offering varying solutions can be very daunting. Just understanding the myriad of solutions can be difficult enough without adding in products, terminology, etc. What makes it extraordinarily difficult, in my opinion, is when proposals are vague.

In flat commercial roofing, there are a few key points to keep an eye out for in a quality proposal. They are:

Tear Off or Go Over: If there are two or more roofs, or if the underlying insulation is wet, a tear off is generally required. If one roof is in place and only a few areas are wet, then the wet areas can be replaced on a limited basis. However, in flat commercial roofing, there is a big cost difference between removing the existing roof system and going over it. Therefore, it is very important to know what solution your contractor is proposing.

Insulation Thickness and “R” value: Typically, in a go-over application, a minimum of 1” polyisocyanurate insulation or ½” HD polyisocyanurate insulation is used as a separation between the old roof system and the new roof system. However, if a full tear off is being completed, building code typically requires that the insulation be brought back to code. In 2020, this could mean installing 4.5” to 5.2” of insulation, depending on what building code calls for in your state. This is another reason why a full tear off is so much more expensive. It’s not just the cost of the tear off, it adds the cost of the additional insulation as well.

Insulation Type: Typically, most flat commercial roofing contractors will recommend polyisocyanurate insulation on a flat roof system. It is by far the best product available for flat commercial roofing. If Fiberboard insulation is being proposed, be aware. Although cheaper, Fiberboard absorbs water like a sponge, which will cause a variety of problems down the road. Some of these problems include deteriorating the structural decking and causing premature failure of the roof membrane. 

Manufacturer: Which manufacturer is being used can make a big difference in product quality and product cost. Using a reputable manufacturer is extremely important because they will not only make a better product, but they are also more likely to stand behind their product. At Chaffee Roofing, we typically recommend Carlisle, Firestone, or GAF.

Membrane Type: TPO, EPDM, and PVC are the most common products available. However, modified bitumen and built-up roofing are still used by some customers. Knowing which roof system you are getting and the basic pros and cons of each system are essential to making the right choice for your building. No roof system is the silver bullet.

Membrane Thickness: Most single-ply membranes come in thicknesses of .045 (Thinnest) to .080 (Thickest). Currently, .060 is the most common membrane that we install because it is generally the best price to performance. However, if your roof has heavy foot traffic, or if you want to maximize the longevity of your roof system, consider a thicker membrane.

Attachment Type: There are four main attachment methods of single ply roofing. They are fully adhered, mechanically attached, ballasted, and rhinobond. Each attachment technique has different costs, strengths, and weaknesses. It’s important to understand what your contractor is proposing and why in order to make the best choice.

Warranty Type and Length: Understanding the type of warranty you are getting is very important. A longer warranty is not always a better warranty. Getting a full system warranty that includes labor and materials is very important because it avoids finger-pointing and excuses. Most of the membrane manufacturers will include the contractor’s workmanship as part of their warranty, which also means that they will provide a roof inspection at the end of the project. Having a third party inspection by the roof manufacturer who owns the warranty is crucial for providing peace of mind.

At Chaffee Roofing, we always try our best to provide a thorough proposal that explains everything we are suggesting to give you the best roof. However, there are so many different solutions available that we always encourage our prospective customers to meet up with us and review our proposal in person. It’s always easier to understand a solution after a face to face meeting with someone knowledgeable on commercial roofing.

Peter Chaffee

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