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Corugated is Everywhere
Take one drive through an American agricultural area and you will be reminded that old corrugated roofing is everywhere. Known for its signature “waves,” created by rounded ridges and grooves, corrugated roofing was installed as far back as the late-1800s and early-1900s. The unique corrugated shape adds strength to panels constructed of lightweight aluminum, steel, FRP (fiber-reinforced plastics) or cement, making corrugated an attractive construction option through the early- to mid-1900s. Not as popular as it once was, corrugated is still available from all major manufacturers today.
Older corrugated was originally known as “Corrugated Galvanized Iron,” or “CGI,” for its galvanized coating. While modern galvanized technology has greatly enhanced the rust-resistance of today’s corrugated, the same cannot be said for older galvanized. On a typical decades-old building, the corrugated panel’s finish and fasteners could be severely rusted and rubber washers could be broken down by years of UV rays. Slotting could also be prevalent. “Older” corrugated had good service life but after 40 or more years, the elements naturally effect finish and the roof loses its ability to keep the building weathertight. This means millions of square feet of corrugated roofing are in service but deteriorating.
Challenges of Corugated
Deteriorating corrugated roofs nationwide present a unique design dilemma to architects, engineers, and other roofing professionals. Given some of the irregularities of the typical corrugated panel, isn’t it better just to tear off that old roof and start again? Is there even another option? While there are circumstances where an old roof should be removed, there are also times when the best, strongest, most affordable option is to leave the old corrugated roof in place.
Corugated Retrofit Solution
A growing number of contractors are becoming aware of the traditional metal-over-metal retrofit, but far fewer are educated about corrugated retrofit options. The corrugated retrofit can be an untapped solution for many jobs that will allow the resourceful professional to truly expand his business and array of design solutions.
Some aspects of the corrugated retrofit are similar to that of a traditional metal-over-metal retrofit. For example, the existing roof remains in place and a new roof is mounted above it with a retrofit framing system. In both retrofits, installation may be installed between new and old roof. However, similarities end here.
The infamous irregularities of the corrugated roof preclude contractors from installing traditional retrofit systems. Differences in height between ridges and lows and variations in the horizontal distance between ridges can make corrugated roofs incompatible with a rigid overlay structure. Laps in corrugated panels create an uneven mounting surface, and in some areas panels could even be stacked three high (in a corrugated asbestos application this could mean a sizeable difference of around 3/4-inch). The uniform clip heights and rigid, rollformed shape of traditional metal-over-metal retrofits simply would not enable the existing corrugated to make “direct-connects” with a linear retrofit overlay member.
The unique properties of a corrugated roof call for a unique retrofit solution. Few in the retrofit industry offer specialized retrofit systems for installation of a new metal roof over corrugated. Specifications of systems may vary, so it’s advisable to choose a company that offers strong customer support and truly solves the problem. A successful corrugated retrofit system will be designed to accommodate variations in the corrugated panels. This can, for example, be achieved with clips of varying heights that allow recessed channels to sit above the purlins at a consistent height. Whatever the design, savvy professionals will ask lots of questions until they feel confident they’ve found the strongest solution.
Benefits of a Corugated Retrofit
When installed in the proper application, a corrugated retrofit can benefit engineers, architects, building owners, and contractors alike. Cost savings, enhanced strength, ease of installation and safety top the list.
Cost: Out-of-pocket costs for removal and disposal of an old corrugated roof may be much higher than the long-term return on investment savings associated with the installation of new roofing panels. The removal process can be time consuming and, in many instances, will disrupt operations of the building. These expenses often far exceed the cost of a retrofit.
Strength: Some retrofits can increase negative and positive loads of a new roof system. By using an overlay system, positive loads like snow weight are held away from the existing corrugated roof. By using a deflection limiter system, the new roof system may have the ability to meet higher load requirements imposed by new building codes. Consult a professional engineer.
Ease of installation: Corrugated retrofit systems are easy to install. For example, one leading solution is a simple two-part system. Installers place a clip at a prescribed distance along the existing purlin, providing a platform for the recessed hat section. Once these two pieces are in place, the new roof panels can be installed.
Safety: Choosing to retrofit an old corrugated roof enhances safety for installers. Leaving the old roof in place can decrease the fall hazard and creates a sturdy lay-down area for materials.
Retrofit Wrap-Up
In a word, consider a retrofit on your next job with corrugated. Incorporating this newer retrofit approach into your design solution repertoire can grow your business and impress your clients. The benefits are many and the solutions are out there!
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Tim Lane is the president of TopHat Framing Systems, Painesville, Ohio. For more information, visit www.tophatframing.com.