Securely sealing a metal roof can be a daunting task. The most obvious, and most serious, problem is the lack of stability. The dimensions of a metal roof are constantly changing. One hundred feet of roof can expand and contract as much as two inches in any single direction. The perpetual stress that this process places on seams and fasteners is the cause of 90% of all metal roof leaks.

What can you do? There are really only two options: replace the roof at significant cost (and wait for the inevitable problems to recur) or apply an elastomeric roof coating to the existing roof.

Elastomeric coatings vary in quality and price. Higher-quality options that stretch further as the roof changes shape will be more expensive, but they remain a bargain compared to complete replacement.

In addition, elastomeric coatings offer dramatic energy savings. The surface temperature of a coated roof may be as much as 40 degrees cooler than the same roof uncoated. Thus it will cost much less to cool your building in hot weather. (This insulating quality ties back to leak prevention as well: Since your roof will be absorbing less heat, it won’t be expanding and contacting as much.)

The coating procedure itself is not complex, but a certain amount of preparation must be done ahead of time. You can certainly take on the task yourself, but the summary of the process that follows this paragraph is likely to make a qualified and experienced roof coating contractor seem very appealing.

First, the roof should be cleaned as thoroughly as possible with a high-power pressure washer. Then it should be carefully checked for rust. An inhibitor should be applied to any area that appears to be corroded.

The next step is applying elastomeric roof cement to fill space around any openings in the roof that allow any kind of access to the interior: air ducts, fans, pipes of any kind, and so on. Flashings should also be reinforced, or replaced.

After the cement has dried, any missing fasteners should be replaced, and all fasteners should be individually sealed with a product like Rivet Guard. Every seam should be sealed with tape, a thick elastomeric cement, or a combination of both.

As you’re scheduling the coating process, keep an eye on your local weather reports. The roof surface should be completely dry, since elastomeric coatings will not adhere to wet surfaces. You should be as certain as possible that no rain is predicted, and that the temperature will remain above 55°F.

Roof coating sprayers are available from home improvement retailers and other paint suppliers. The instructions for the coating product you choose will specify the appropriate sprayer head. Depending on the product, you may need to apply a primer coat, and two applications of two coats of the topcoat will be needed to wrap up the job. 

When your new elastomeric coating has dried, you can feel confident that your roof is protected against the kind of leaks that can compromise the structural integrity of your building and threaten your equipment, inventory, and daily operations.