If you've never heard of hypertufa, let us explain why this concrete look-alike is the perfect material for an outdoor table. Made from a mix of cement, peat moss, and perlite, hypertufa has much of concrete's strength and durability, but it weighs a lot less, doesn't require sealing, and has a more textured, organic appearance. Senior technical editor Mark Powers cast a tabletop with a recess for adding easy-care sedum and designed a notched cedar base that can be taken apart and stored flat. Hypertufa requires a few weeks to cure, so get started now and you'll be able to show off your handsome new table before summer draws to a close.
Overview for Making a Hypertufa Table
1x2 legs: 4 @ 14 inches
1x2 upper support blocks: 4 @ 11 inches
1x2 lower support blocks: 4 @ 3 inches
1x4 form frame, short sides (scrap): 2 @ 28 inches
1x4 form frame, long sides (scrap): 2 @ 30 inches
1x4 reinforcement blocks: 4 @ 3 inches
¾-inch rigid-foam insulation: 1@ 20 by 30 inches
¾-inch rigid-foam insulation: 2 @ 7 by 14 inches
1x4 lower crosspieces: 2 @ 10 inches
1x4 upper crosspieces: 2 @ 21 inches*
1x4 lower stretcher: 1 @ 31 inches*
1x4 upper stretchers 2 @ 31 inches*
*After they're cut to length, miter the ends of the upper crosspieces and all three stretchers at opposing 45-degree angles, and clip 1 inch off the long points of the ends. For each piece, the longer edge will be the top edge.
Notch cut instructions:
All notch cuts are ¾ inch wide and extend to half the width of the board, or 1¾ inches. Always measure the positions for the notches along the top (long) edge for each piece, no matter which edge the notches are cut on. See diagrams for positioning and sizing.
For each 1x4 lower crosspiece:
The notch should be centered on one edge of the board; the notched edge is the top edge and will face up during assembly.
For each 1x4 upper crosspiece:
Cut notches on the top (long) edge. Position the notches 3 inches from each end, measured along the top (long) edge. The notches will face up during assembly.
For the 1x4 lower stretcher:
Cut notches on the bottom (short) edge. Position the notches 4 inches from each end, measured along the top (long) edge. The notches will face down during assembly.
For each 1x4 upper stretcher:
Cut notches on the bottom (short) edge. Position the notches 3 inches from each end, measured along the top (long) edge. The notches will face down during assembly.
Prep Day: Cut and assemble the form (Steps 1 through 5).
Saturday: Make the hypertufa mix and cast the tabletop
(Steps 6 through 10). Wait a few weeks for the tabletop to cure.
Sunday: Assemble the base and set the tabletop on it (Steps 11 through 18).
Cut the Pieces for the Form
Use a miter saw to cut scrap 1x4s into long sides, short sides, and reinforcing blocks.
Screw the Form Together
Place two reinforcing blocks flush with the ends of each long side. Secure them by driving 1 inch screws through the blocks and into the long sides. Sandwich the long sides between the short sides, with the blocks facing outward, as shown; the ends of the short sides extend past the blocks so that the form can be pulled apart easily when the tabletop has cured. Mark locations for pilot holes on the tops of the short sides and the edges of the blocks. Drill 1/16-inch pilot holes through these marks. Secure the form by driving 1 inch screws through the pilot holes.
Tip: You can make the tabletop longer or wider than ours, but doing so may require adding extra stretchers or crosspieces to the base for support.
Cut the Foam to Size
Use a utility knife to cut a piece of ¾-inch rigid-foam insulation to fit snugly inside the form. Press the foam into place until it sits on the work surface, flush with the form's bottom.
Make a Platform for the Recess
Cut two pieces of foam to the desired size of the recess for the planter. Stack them on top of each other, center them atop the large piece, and sink 2-inch deck screws through all three layers to secure them.
Cut the Wire Mesh
Wearing protective gloves, use wire snips to cut a piece of hardware cloth to fit inside the form. In its center, cut out a rectangle that's 1 inch shorter on all sides than the platform you made in Step 4, and set aside the cutout for Step 8. Snip the corners of the cutout area so that you can bend the edges upward around the platform, as shown. Set aside this piece of wire mesh for Step 9.
Combine the Dry Ingredients
Wearing a dust mask, put 12 quarts each of cement, peat moss, and perlite into a mixing tub. Use a hoe to combine the ingredients thoroughly.
Add Water to Make the Mix
Add a few cupfuls of water to the dry ingredients and use a hoe to blend it in. Continue adding water in small quantities and blending it in until the mix reaches the consistency of creamy peanut butter. If the table will be left outside year-round, add a small amount of acrylic fortifier to the mix, according to the manufacturer's instructions, to prevent the tabletop from cracking.
Fill the Form Halfway
Coat the form's interior with petroleum jelly or cooking spray so that the tabletop can be easily removed later. Add hypertufa mix until the form is filled halfway. As you work, use a scrap block to level the mix, and tap the form with a hammer to get rid of air bubbles.
Place the Wire Mesh
Lay the large piece of wire mesh on top of the mix so that the edges around the platform are bent upward. Add mix until the platform is covered by no more than 1/4-inch. Lay the wire mesh cutout on top of the mix, over the platform.
Finish Filling the Form
Add mix to the form until the mix is flush with the top, again leveling it and getting rid of air bubbles as you work. Cover the form with plastic to retain moisture for a slow, steady cure. Let the tabletop cure for a few weeks.
Cut and Miter the Boards
Cut cedar 1x2s to size for legs and support blocks, and cedar 1x4s to size for crosspieces and stretchers. Use a miter saw to cut the ends of the stretchers and upper crosspieces at opposing 45-degree angles, and clip 1 inch off the long points of each.
Cut Out the Notches
Refer to the overview diagram. You'll cut notches on the bottom (short) edges of the stretchers and on the top (long) edges of the crosspieces. Each notch will be ¾ inch wide and will extend to half the width of the board, or 1¾ inches. Mark the notches with a scrap 1 block turned on edge, and make the cuts with a jigsaw.
Tip: Use a pencil to label the top edge of the crosspieces and the bottom edge of the stretchers so that you'll know what edges to cut the notches on.
Dry-Fit the Sides
Place an upper crosspiece on a work surface, notches facing upward. Place two legs below it with their tops abutting the crosspiece, and align the outer edges of the legs with the inner edges of the notches. Lay upper support blocks onto the upper crosspiece and legs so that they're flush at the top and fall between the notches. Lay a lower crosspiece onto the legs with the notch facing upward, abutting the upper support blocks and flush with the legs' outer edges. Lay lower support blocks onto the legs, abutting the lower crosspiece and flush with the legs' bottoms. Repeat for the second side.
Tip: The pieces of the base should fit snugly, but if the notches are a bit tight, use a wood file or a narrow piece of scrap wrapped in sandpaper to enlarge them.
Assemble the Sides
One by one, lift each piece that's on top, apply a polyurethane glue such as Gorilla Glue to its back, and set it back in place*. Tack the pieces together using a pneumatic nail gun and 1-inch brad nails. Repeat for the second side.
* follow package directions to best ensure successful bonding
Fit the Base Together
Stand the sides upright with the lower crosspieces facing each other. Fit the stretchers into the notches on the crosspieces.
Remove the Form
Flip the form over and place it on a work surface, foam facing up. Use a drill/driver to remove the screws. Push on the tail ends of the form's short sides to tilt them down and away from the tabletop. Pull off the long sides and remove the foam.
Tip: If foam still sticks to the tabletop after it has cured, slip a razor blade under the edges of each piece and pry it off bit by bit.
Smooth the Edges and Surfaces
Run a scrap block of wood over the edges, corners, and surface of the tabletop to soften rough spots and scrape away any leftover foam.
Position the Tabletop on the Base
Center the tabletop on the base; its weight will hold it in place. If you like, add sedum or another plant that thrives in shallow soil to the recess. Over time, the tabletop will lighten in color, while the cedar base will weather to a handsome gray.