2008-11-10

Forms for custom concrete pavers


Because it was so windy Sunday, I stopped my exterior painting and prep and used my table saw to make parts of the paver forms that I'll soon need. I cast my own concrete pavers and I'll need more outside my new bedroom door - at least 4 and likely 6+. I've grown to really like the advantages of using stacked or ground-set pavers and bricks for garden hardscape - the ability to move and reset the pieces is a huge advantage over poured-in-place or mortared-in-place pieces is huge.

However, it's also fair amount of work to cast pavers using the methods that I'll tell you about. For one, the paver size I call for here is probably 120+ pounds when its done so you need to think about whether you can even heft that around your yard and the sweat you'll build up mixing that volume of concrete. Nonetheless, the payoff is something that's completely custom and potentially wildly different than your typical poured-in-place or purchased paver.

The sides of my paver forms are 2.5" x ~19" x ~32". I cut them from melamine-coated particle board. The 2' x 4' melamine sheet that I purchased from Home Depot gave me the pieces that you see here - enough to make three forms and have three long pieces left over for spares. An efficient use of material is to cut the six short pieces from the 2' side of the melamine board first, then the 9 longer ones from the long side of the remaining board. You'll eventually cut the boards to their final length, but the cut off portion is minimized using this method.



The exact size of the pavers I've already made was 19-3/4" x 32" which is very close to the Golden Ratio. The 32" dimension was set by the largest width I could accomodate in my side yard. I'll keep those dimensions with the new forms in order to emphasize continuity and repitition across the yard.

From past experience, I know that it's difficult enough to make two pavers at the same time, both from an available space standpoint and from a labor standpoint. All that concrete mixing and hauling is hard work! I have materials enough for three, so that third one will be an option if I can make it work.

When the forms are assembled, I place them on a textured piece of plastic like this. The plastic is on my "pouring table", a 5/8" piece of plywood with 1x4 stringers underneath to keep it flat under heavy load.

The textured plastic is from a fluorescent light and available at Home Depot for 5 or 6 bucks. I used a pebbled pattern, but grid patterns are also available. These form bottoms are actually pretty expensive since it's only reusable a couple times before it degrades too much.

The forms are then sealed along all the corners. I use a black silicone-modified latex (gotta check this) . Black has a nice contrast against the white melamine, so it's easy to see. Cheaper non-silicone caulking forms a much tighter bond to the paver and creates a problem when I disassemble the mold. Smooth the seal down with a wet fingertip and you have a nice chamfer on the edge of your paver.

Decorate the bottom of the form with things that you like. I've had good success with Magnolia leaves and garage ephemera. I weight the leaves down with bricks and glue them to the form bottom with carpenter's wood glue. They eventually come out of the concrete, leaving a pleasant impression behind. I've also used pieces from my old Alfa Romeo, bicycle parts, and coins. Flat, thin, pieces like coins that are to be embedded in the concrete are harder to work with- they can pop loose. One way to address this is to epoxy a wood screw on to the back of the object to give it some grip into the concrete.

Then it's all about mixing and pouring the concrete. More on that later....


The basis for my concrete knowledge comes from having done this before. But prior to that, I read Fu-Tung Cheng's marvelous book, Concrete Countertops. Eventually I will have a concrete countertop as well, but that's a story for another day.

If this information is useful, try the concrete paver tag link at the bottom.