Introduction: Easy Outdoor Cinder Block Benches
We admire the bench on our neighbors' front patio, so we decided to make some for our back patio along the fences. These are easy for anyone who can carry, glue, and paint cinder blocks and wood posts.
In the interest of time, we bought some seat cushions (not shown), but I'm sure some of you would love to make those, too.
Step 1: Measure and Plan
Here, I'm showing the finished bench to illustrate the goal. We divided the length of fence where each bench would go into segments about 4 feet (1.3 m) wide. So one bench needed both ends plus one support in the middle. The other needed two supports in the middle.
Step 2: Tools and Materials
- caulk gun
- Hand saw , or circular saw
- drill (if joining multiple posts for length)
- paint sprayer or roller, brush, etc.
- cinder blocks (4 per support)
- construction adhesive (one tube glues about 3 supports)
- wood posts (5 per bench)
- carriage bolts, nuts and washers (5 per bench, if joining multiple posts for length)
For each support, you need four regular double cinder blocks (8x8x16 inch ~20x20x40 cm) and one single (8x8x8 inch ~20x20x20 cm). You also need wood posts long enough to go through the supports in the ends plus a little extra. I have mine extending 6 inches (15 cm) past each end. The longest posts we could get at our stores are 12 ft (4m) long. Since we need about 17 ft on one bench, I decided to join posts inside the blocks with half lap joints as explained later.
Step 3: Glue the Blocks Together
First, I glued together the three cinder blocks stacked to create clamping pressure. After the glue cured, I turned them upright (two holes high and three holes wide) to glue on another block on end for the back. Finally, I glued in a half-block and used clamps to apply pressure to the joint in the horizontal direction (last photo in this step).
Step 4: Cut Half-laps (if Needed)
As I mentioned, I needed longer posts than I could buy, so I decided to hide the joint inside one of the supports. I cut the posts with an extra 3.5 inches of length, then used a circular saw to cut the half-lap as shown. I lined the posts up and cut them all at the same time. I used a clamp-guide to cut halfway through 3.5 inches from the end. I used a 1/4 inch thick board as a guide to cut across the ends. Then I realized it would have been easier to limit the overlap to the max depth of my circular saw (which is more like 2 inches, not 3.5)!
Step 5: Keep Cutting (if Not Wise Enough to Avoid This Step)
My punishment was to cut the rest of the way with another saw. I used my grandpa's hand saw for one, then decided I didn't want that much exercise, so I cut the rest with a saber saw. Again, if you only overlap the posts by the max depth of the circular saw, you can avoid this step.
Step 6: Paint/stain
I used a HVLP paint sprayer to prime and paint the blocks. I tried the sprayer for staining the posts, but found I liked the control I had with a roller better.
Step 7: Install the Posts
I cut out some pieces of cardboard as shown, then rolled them up into square tubes and installed them in the holes in the blocks as sleeves to protect the finish when inserting the posts. After inserting each post, I pulled out the cardboard tubes and put them in the next row of holes.
Step 8: Join the Half-laps (if Needed)
Where I needed to join posts, I drilled through the middle of each joint and installed a carriage bolt, washer and nut. Then, I slid the joint into the block, where it wouldn't show.
That's basically it. If you don't have to join posts, you can see how it's even simpler. We had three generations over to the house for our first party on our back patio, and the bench was great. As I mentioned, we ordered some cushions to go on it. We found it was fine for seating, although a little low. With cushions, the height is great and overall more comfortable.
Step 9: P.S.
If you like this style of step-by-step instruction, please share with others and subscribe, so you'll be notified when I post more. If you have questions, please post them in the comments. I will try to answer and probably update the instructions, too. Read about more of my woodworking projects and tools at ChipsWoodShop.com.