In late 2024, Caldwell’s Roofing got the chance to install an old-style roofing material—flat lock copper panels—on the George Washington Carver Museum in Tuskegee, AL. The three porch roofs featured build-in gutters that would also need custom-made and soldered copper work. Working with DRI, Inc., a company that does several national park projects, they tackled the gutters first, bending and soldering what could be done beforehand in shop, and assembling the 10′ pieces together with hidden clips/copper nails for main attachment (while allowing for expansion/contraction of heat/cold) and copper rivets, flux, and solder for lapping joints.

After the gutters were in place, they began installing copper sidewall/endwall flashings and the flat lock copper panels, providing a stagger for each row. Prior to installing a panel with clips and copper nails, they fluxed the already pre-tinned panels along the marrying edges. Applying a quality flux is likely the most critical step in the process, as it helps sweat the solder further into the joints. As seen below, our test strip shows the solder passing all the way through the triple (z-shaped) marriage joint. While some people recommend Ruby Fluid or Stay Clean Flux, LA•CO’s ‘M-A Flux’ product is top tier. Another choice in soldering is whether to use a torch (easier, faster, more dangerous, greater chance of catching underlying roof on fire) or an ‘iron’ (that is still heated by a fairly closed torch) such as the Express Soldering Iron.

A (red or brown) rosin building paper is recommended and was used here to help prevent the copper panels from getting stuck in the ice and water shield underlayment. With the building paper, the panels can more easily slip slightly as they expand and contract. Another key facet in copper soldering, when using an iron, is to paint flux all over the tip once every 30 seconds (and don’t let the iron get too hot). Oxidation will eat away at the tip and make it unusable very quickly if this advice is not heeded. Some black will still accumulate near top of tip—this is fire scale, and occurs because you can’t tin the entire tip. A bench grinder or wire wheel on a drill can remove some oxidation if correctly prior to too much tip damage. So-called long-life tips use a Nickel coating on the top to help maintain the connection from heat source to heel of tip, but won’t protect against forgetting to keep the tip fluxed nearly continually. The tip oxidizes while hot, but once it cools down and is in the shop, it is safe from rapid oxidation. Flux is sometimes called ‘acid,’ because of historical roots, but is extremely weak these days and okay to apply straight to the iron with a brush. Also, it is better to paint flux on your tip than to dip it in flux/water mixture, as the cooler water can cause stress cracks, due to brass/bronze having a hot short point. The inside of a hot tip may be at hot short, while the outside getting dipped in cool water contracts and may crack.

Installing the panels took lots of solder—probably north of 100 pounds for roughly 4 squares of roof. The 1/4-lb stick variety was easiest to use. After soldering the panels, they were wiped with a damp rag to clean off any residual flux (which accelerates color change of the copper). A dead-blow hammer was used to flatten the marriage seams of the panels after installation and just prior to soldering. The trick with soldering is to get the copper ‘warm’ over a large area (so wider tips do best). If temperature permits (above 70º F), electrical soldering irons may be used. The express soldering iron used on this job required a propane tank and connecting hose (with regulator).

As a quick primer on roof coatings, elastomeric/acrylic are at the bottom, polyurethanes are above that, and a top-tier product is IB Roof’s PMMA. It is a multi-step, 2-part mixture that provides maximal resistance to leaks and failure.

In January 2025, we got a call to look at this home and bid it for a new roof. After extensive planning, we decided to go with 80-mil IB PVC, replacing the old built-up roof and tapered insulation board system beneath it with a slightly steeper slope system. The owners mentioned it was a Paul Rudolph house, an architect student of Frank Lloyd Wright (the emphasis on horizontal lines/planes is certainly present!).

The roof presented a few challenges. Due to it not being perfectly planar (after the several decades since being built in 1954!), we used ‘Q’ type tapered insulation boards (they grow in height from 1/2″ to 2 1/2″ over 4′, offering 0.5″:12″ slope), and built reverse crickets on three areas that were pooling water. In one badly leaking area, we replaced decking, sistered joists, and installed a section of steel angle iron with lag screws to help repair the vulnerable section of house.

The drainage system for the roof was also unusual. It was a hip roof (with very low slope), but the bottom edge had a ‘gravel stop’ to guide the water to 6 scupper/gutter outlets. The gravel stop was unconventional though, having a profile of several bends to it. We used PVC-clad metal, bent to appropo profiles, to from the edging metal and the scupper/gutter outlets. This metal can then be welded to with the PVC membrane, ensuring a seamless, water-tight transition. Incidentally, on the lower overhang roofs, since they were had hardie board underneath, the owners requested an unusual detail—flat edging in lieu of traditional drip edge! You need an edge of PVC-clad metal for the membrane to weld to, but I’ve never bent or used a flat piece (with only a tiny 3/4″ closed hem under helping encourage water away from wicking under). I don’t recommend it, but for a decorative and water-hardy roof deck, it does fit the horizontal-only look.

The owners requested an NDL warranty (added $400 for this residential project), so we made sure to follow or exceed IB’s installation guidelines, including placing T-patches on all intersections of weld seams, and placing mechanical fasteners at 6″ centers on the perimeter and 12″ centers in the field.

All in all, we’re quite pleased with how it turned out! We spent a week of heavy labor on it, and another couple weeks on the tedious details such as the overhang roofs. The house was a joy to work on, getting to see all the various architectural touches that were made in the design.