Back in 2009, my remodeling company took on the renovation of a 105-year-old three-story brick structure, vacant for the past 10 years, here in Louisville, Ky. The job included an extensive interior gut and energy rehab along with a new, one-story addition at the back. The original standing-seam terne metal roof (terne is a lead/tin alloy) was intact but in need of attention. We wanted to both restore the original roof and match its appearance on the roof of the addition. As with most remodeling jobs, the budget was a driving concern. But we also wanted to make an example of this home, to show how builders can conserve existing materials when possible.

While it may have been more expedient to tear off and replace the old roof, it would also have been costly and unnecessarily wasteful. Instead, we decided to revive the old, corroded metal with a product called Hydrostop PremiumCoat (800/739-5566, www.hydro-stop.com), an acrylic elastomeric liquid membrane that's applied over a reinforcing...

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