I was reminded recently that what we hit the road selling and installing every day is not really all that sexy. A great-looking new steep-slope roof is as close as it comes, but for many folks getting a new roof is about as desirable as a certain dental procedure…you know the one.

Well, if exploring the options to purchase a new roof is not thrilling, imagine how mundane it is for most folks when we start talking about what goes under the roof. The underlayment is not, however, an unimportant feature in a steep-slope roofing system. Contractors dedicated to delivering a quality roof must be well versed in all facets of the roofing system, including the underlayment.

Today’s underlayment options are broad. Most asphalt shingle manufacturers offer an underlayment designed to go with their roofing systems, and there are numerous manufacturers of synthetic underlayment products. Of course, the old standby, organic asphalt-saturated felt, is readily available and inexpensive.

But asphalt felt has not always been readily available, as this column noted back in the summer of 2001. This brief period of shortage gave synthetic underlayment products the boost needed to get the attention of roofing contractors. Makers of synthetic underlayment touted large, lightweight rolls that were easy to install, always laid flat and were readily available. They claimed superior waterproofing characteristics that allow them to last longer than asphalt felt when exposed to the weather.

Indeed, synthetic underlayment products have taken a decent portion of the underlayment market in spite of the typically higher cost compared to asphalt felt. From my observations over the years, synthetic underlayment products have lived up to their claims, and many roofing contractors I know would use nothing else. Not taking anything away from asphalt felt; it has its place and continues to be a product of demand by roofing and building contractors.

Of course, when a roofing product hits the market and has some success, the “better mousetrap” is never far behind. Unfortunately, the definition of a better mousetrap for many is one that is cheaper. That is a shame in the case of synthetic underlayment products, as their main attraction, in addition to the easier handling, is their superior weathering characteristics.

As with anything you choose to make part of the roof you sell, you must know the underlayment. A poor choice of underlayment, such as an inferior synthetic product, could result in some unwanted consequences.

How do you choose? I have always been a fan of following the roofing manufacturer’s recommendations. This includes the underlayment manufacturer’s instructions that should give you a good indication of which systems they match up with and which to avoid. If you are changing your underlayment scheme, ask around and do the research.

So, is there a way we can make the underlayment seem a little more attractive to owners? Maybe we should take a page from the undergarment industry and start calling it the “foundation course.” The truth is the underlayment does serve as the foundation for the steep-slope roofing system, and anything built on a poor foundation is bound for an early demise.