To allow for expansion of the new concrete casting, and to make removal easier, he wrapped this box with 1/8″ sill-seal closed-cell foam. Since the original blocks were hollow, he inserted an open-ended box in the mold, which he centered and screwed to the base to keep secure. Marty chose pre-mixed high-strength concrete mix for his castings. The original blocks were made from a dense mixture of Portland cement and sand. Marty fills around the form with concrete, adding rebar for strength at mid-fill, and finishing by vibrating the interior block to spread the concrete. He let the plaster cure overnight, then disassembled the form and cut along each side of the mold with an oscillating tool to gently pull the pieces away and remove the original block. He designed the form with 3″ to 4″ between the sides and the original block, which makes the mold sturdy enough to use repeatedly, and wide enough to trowel in the wet plaster.Īfter all the surfaces were well-coated with a petroleum-based release agent, he mixed enough plaster to trowel into the cavities, lightly tapped the sides to settle the wet plaster, and screeded the top for a flat surface. He screwed the form together so that after the plaster sets, the mold can be unscrewed easily and pulled away from the new piece. He chose melamine-surfaced particleboard for the form because it’s less porous than bare wood, which makes it easier to remove from castings. Marty began by building a form to make the mother-mold. Once the mold had cured, he unscrewed the form and cut along the sides to remove the original block. To create the mother-mold, Marty assembled a form around the original block, then filled it with plaster. These molds wouldn’t last forever, but they would hold up for the number of blocks needed, and the materials were both locally available and inexpensive. Since he didn’t need to make numerous copies, he chose to create mother-molds for the project out of molding plaster. Although it’s possible to buy mold-making materials that can be used repeatedly, because Marty needed to copy four designs (the fifth was an altered version of another), the cost of the materials would be prohibitive. His first issue was how to make molds for the five rusticated block shapes: pier blocks, tapered bases, tapered column capitals, column drums, and column disks, all with the same rough-hewn finish. While the process isn’t rocket science, it is slow and tedious. Marty was aware of some local attempts to replicate cast blocks. That’s when he discovered Marty Naber of Naberhood Restorations. At this point, many homeowners would have given up, but as a vintage-car enthusiast, Gary knew that anything can be done if you find the right person. A local contractor, Doug Shultz, began repairs-removing and rebuilding the footings, and making structural repairs-but then the work stalled. A catch-22 developed as carpenters commented that the project was mason’s work and masons insisted it was a carpenter’s domain. Gary spoke to at least nine contractors many came by, looked at the porch, and never called back. With new concrete blocks, the porch is ready to weather another century. Gary was left with two choices: Find salvaged cast blocks for repair, or find a mason who could cast new blocks to match the old. Substituting modern blocks would have been unsightly, and replacing all the blocks would have changed the character of the porch. Unfortunately, the porch was falling apart, and needed an additional column to correct a sagging roofline. The porch-from the foundation piers to column capitals and even the apron in between-was constructed of cast ornamental concrete block, a material that was quite popular at the turn of the 20th century but went out of production by the 1940s. Homeowner Gary Stottler knew it wouldn’t be easy to restore the front porch on his circa 1900 Queen Anne because of the material used. This Queen Anne porch is more appealing with the help of concrete blocks.
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