HURRICANES, HAIL, HIGH WINDS and the relatively short life span of composition roofing are forcing reroofing decisions on homeowners. When the protection over head fails, the homeowner is faced with many replacement options to consider.

Perhaps the most apparent option that comes to mind is to reshingle. However, the tear-off mess, dump fees and high cost per year of another temporary roof may make this option undesirable. A few homeowners with less limited budgets may consider tile or slate for a more durable roof. However, the expense, structural strength required to support the added weight and architectural compatibility of these natural roofs cause many to nix these options.

Fortunately for us, in one area or another of the metal roofing industry, more and more homeowners are choosing to reroof with metal. Metal offers longevity because, for most homeowners, it will be their last roof. This long life span provides a much lower cost per year than composition shingles. Metal roofing also offers a wide variety of styles and, in many cases, 20 plus colors to choose from; most decision makers can find a desirable selection.

In my experience, most metal roof problems are minor and easily corrected, such as improperly installed flashing, vents, closures and pipe boots.

Now that the decision has been made to reroof with metal, the expectations of the homeowners probably are very high. They are looking forward to a beautiful green, red, blue, burgundy, teal, etc., roof they will be proud of as long as they reside in that home. They are perhaps expecting lower homeowners insurance costs because they now have added wind protection and a roof with a Class 4 impact rating. In addition, the homeowners know their new metal roof will be appealing for a long time because the roofing contractor, rollformer or coil coater has provided a 20- to 30-year finish warranty.

As a former metal roofing contractor and next as a manufacturer of commercial and residential metal roofing, I have seen the premature failures of what was believed to have been a permanent roof system or a lifetime roof system. Imagine the disappointment when homeowners Mr. and Mrs. Smith are told their "last roof" needs to be replaced and there may be other damages that will be determined after their "last roof" is removed.

If problems surface from underneath the metal in 10 to 15 years, the homeowner is left holding the bag.

In my experience, most metal roof problems are minor and easily corrected, such as improperly installed flashing, vents, closures and pipe boots. Although annoying, these problems are miniscule compared to a total roof failure caused by what is below the metal.

When injured, one does not simply bandage the wound without properly treating it first. Just cover it up, and more than likely the wound will become worse. Unfortunately, there are metal roofs being installed with this "just cover it up" attitude. During the years, I have spoken to several roofing contractors who make it a practice to lay steel roof panels directly over composition shingles without any underlayment or even one by fours. When questioned, the general response is, "Well, we have always done it that way and have never had any problems." My next question asked will be obvious to many. I ask, "How long have you been installing metal roofing?" Usually the answer is in the range of two to five years. Hardly enough for a test of time.

Residential metal roof coverings continue to gain market share and acceptance. This higher demand has provided an opportunity for many composition-shingle roofing companies to become metal roofing contractors. Unfortunately, there are many small companies only around for two to five years. If problems surface from underneath the metal in 10 to 15 years, the homeowner is left holding the bag.

According to a Web article by Jim Guy with CALBAR Metal Roof Paint: "Pay particular attention to instructions with respect to ventilation. Metal roof failures can happen and often the corrosion begins on the underside of the roofing. Condensation can form under some metal roofs. You need to make sure that the underside of the metal roof can breathe readily and dissipate the condensate water and water vapor."

Guy's statement reminds me of a customer, Joe, who had a bad experience with condensation and corrosion before his metal even was installed. Joe was a do-it-yourself contractor; he purchased his green roof panels and tan wall panels before he had his frame ready. I don't recall if he was hedging against the coming price increases or if he was slower at framing than he anticipated. Joe stacked his panels on timbers, raising them a few inches off the ground, and covered the stacks with visqueen. Several months later, he finally was ready to install the panels. Joe showed up at my office and stated that he had received panels with bad paint. I looked up his order and asked what color was bad. He replied that both were bad. After more discussion, he told how he had stored the panels.

I have seen the premature failures of what was believed to have been a permanent roof system or a lifetime roof system.

Representatives from my company, the coil supplier and coil coater were sent out, knowing the cause even before seeing the panels. The condensation between the panels had caused the paint to begin cracking. Fortunately the damage was slight, but unfortunately, we had an unhappy customer. Yes, Joe was given instructions about storing the panels when he picked them up. He just did not anticipate his project taking so long to complete and damage to occur so quickly.

As Guy states, "pay particular attention to instructions with respect to ventilation." Many roofing contractors accidentally ventilate to a degree when they install wood lathing strips under the metal roof. This is certainly better than laying the metal directly on the composition shingles. However, the wood lathing may become the cause of premature roof failure. When condensation occurs on the lower side of the metal, it may travel down to the next wood lathe and settle against the wood, eventually causing the wood to rot and rust to begin to form on the fasteners and the panels.

When condensation occurs on the lower side of the metal, it may travel down to the next wood lathe and settle against the wood.

Marco Industries, Tulsa, Okla., offers a solution to this problem with a product called Retro-Ease. Retro-Ease is a specially formulated foam spacer that is rolled out in strips in place of the wood. The metal roof then is fastened to the roof deck through the Retro-Ease spacer. Retro-Ease, as an added bonus, does not warp or twist like wood may do when it is first installed.

Another product, by E & V Inc., Charleston, Ark., provides ventilation under the panels. Retro-Vent is a heavily corrugated metal strip that comes in 50-foot (15-m) rolls. Retro-Vent is unrolled and tacked in place at each horizontal screw line. Screws then are installed through the Retro-Vent and into the decking. Retro-Vent allows a drain path for condensation and increased airflow between the metal roof and deck.

I have been addressing condensation and ventilation in residential applications. However, in commercial building there also is a growing concern about condensation in retrofit roofing applications and even in new construction. Condensation between the insulation and metal roofing in a metal building has been known to cause purlin and fastener rust. Concerns about condensation in this application are being addressed; Cora-Vent, Inc., Mishawaka Ind., provides a product appropriately called Purlin Vent. Purlin Vent is installed over the tops of purlins to provide air flow underneath the metal roof or wall panels.

Retrofit metal roofs continue to gain market acceptance and market share. This is no doubt because of the aesthetics and longevity metal offers, whether residential or commercial. Expectations are high but may not be realized if attention is not given to what is installed before the metal roof goes on.