Q: What is the quickest and most accurate way to template a countertop in an old house with wavy walls and odd projections?
A: Roe Osborn, senior editor at JLC, and author of Finishing a House, responds: I spent quite a few years working as a joiner in a boatyard. For that job, most of the templating we were asked to do involved curves and irregular surfaces. The tool we reached for most often was called a “spiling block.”
A spiling block is typically a small rectangle made of some sort of hard material. I still use a spiling block that I made back then from a 2x3-inch scrap of 1/4-inch-thick plastic sheeting (see photo), but I’ve made others from thin plywood or hard laminate. (The exact size is not important, but the block I made fits nicely in my toolbox and tool bags). To make a spiling block, cut a rectangle with square sides. Then cut an indexing corner at a 45-degree angle.
For the template itself, I cut strips of 1/4-inch plywood 3 to 4 inches wide. I start with a strip along the straightest wall and screw it to a strip that runs along the wall with the irregularities. Be sure that the template strips are well attached and stable at the corner (some folks use hot glue, 5-minute epoxy, or diagonal strips in addition to screws). Continue building the template until you have strips on all four sides. Secure the template to the cabinet or structure below that will be supporting the countertop.
Slide the square corner of the spiling block into the wall corner or at the end of the wall, and hold the block down firmly against the template strip. Using a sharp pencil, follow the entire end of the block that has the 45-degree index cut, tracing it onto the template strip (as shown in the illustration, below). Now work your way along the irregular surface, sliding the block against the wall and tracing the block onto the strip. Repeat this process at several places along the wall, particularly where the surface changes direction, flattens out, or goes from convex to concave. Write labels or make notes on the template to indicate key locations, such as a corner or a place where there is a change of direction.
To transfer the location of a projection such as a plumbing or electrical chase onto the template strip, use the spiling block to record all of the sides, again labeling each trace that you do. If the block can’t reach all the way to a certain point (such as an acute angled corner), trace the block while holding it against the wall or surface with the long point. Then measure from the traced corner point on the template strip to the long point of the corner and write that measurement on the template. When you transfer the template to the countertop material, simply extend that line to the distance you wrote down.
When you’ve finished templating the entire irregular surface and have labeled any anomalous places, carefully remove the template and place it on the countertop material. If there is a finished straight edge on the material, align the straight edge of the template along that side.
Firmly but gently clamp the template to the material, taking care not to distort the template. Set the spiling block back on the template, and align it with every trace that you made (as shown in the illustration). At each location, trace the other end of the block onto the countertop material, continuing the process until you have transferred every position that you marked on the template.
Now connect the marks on the countertop material. If the curve is subtle, you may be able to connect them with straight lines. If the curve is more pronounced, use a flexible batten to connect the marks for a fair and even curve. When the line is complete, you’re ready to cut the irregular edge of the material to the line for an exact fit.