How to build a workbench
The steps below will enable you to build a free standing 8 foot workbench which can also be attached to an interior garage wall. Most home improvement stores will cut the wood to your specifications for a very small fee (around .50 cents a cut after the first 2 or 3 are free) and it maybe well worth considering if a table saw is not available to rip the 4×8 foot sheet that makes up the top of the workbench and the bottom shelve. All other cuts can be done at home with a handsaw or miter saw.
Table top support pieces
Cut One 2×4 into (5) 18 inch lengths. These will be the supports for the table top of the work bench.
6 legs and 6 end caps
Cut another 2×4 into (2 pieces) 36 inches. These will be 2 of the legs for the workbench. The remaining piece will be 24 inches. Cut the 24 inch piece to 21 inches. This last piece will be the end caps of the workbench. Repeat the process two more times with (2) 2×4 to end up with 6 legs and 6 end caps at 21 inches each.
Assembly — Part one
Lay out (2) 2×4 parallel on the ground with edges up. Nail one 21 inch piece to join the two parallel pieces. Nail another 21 inch piece on the opposite end. This will form a perfect rectangle.
Assembly — Part 2
Pre-drill pilot holes and nail the 18 inch cross pieces (all 5 pieces) inside the rectangle at approximately 14 inches apart. In essence, you are creating the appearance of a ladder that will support the tabletop in place. (It should look similar to the picture above minus the legs)
Assebling the legs
Pre-drill pilot holes and nail the 36 inch legs to all four corners of the frame, make sure to nail them INSIDE the frame where the 90 degree angle is formed at each corner. You want the legs on the inside, not the outside. The remaining (2) 36 inch legs will be centered on the form at equal distance (approximately 4 feet), also INSIDE of the frame. (See picture on STEP 3) Now you can flip it over and you have a perfectly constructed frame, but not solid, not yet.
Bottom support rectangle (remaining 2 end caps)
16 inches from the bottom of each leg mark a line, pre-drill pilot holes and attach the remaining (2) 21 inch end caps to give it support. These are to be nailed on the OUTSIDE of the legs.
Bottom support rectangle
At the 16 inch pencil mark you are now ready to pre-drill pilot holes and nail one 8 foot piece to the outside of the frame (lengthwise), this will connect to the side pieces you did on the previous step. Repeat for the back side of the bench.
The last 2×4
You should now have (1) 2×4 left. Cut the 2×4 into 21 inch length pieces, this should give you 2 at 21 inches and a small piece to use in some other project or throw away. Pre-drill pilot holes and attach these two 21 inch pieces to the inside of the center legs. One on each side of the legs (there will be a small gap between the 2 pieces). Now that you have nailed the two pieces to the inside of the legs, nail them to the front rails to create the proper support. The frame is now solid and ready for the next step.
Installing support brackets
Screw the support brackets on the INSIDE at each corner of the support cross pieces at the top of the work bench. 14 metal brackets total.
Cut the 4×8 foot sheet into 24 inches lengthwise. (This can also be done at the home improvement store prior to taking it home). Spread liquid nails on top of frame to adhere workbench top to frame prior to nailing or screwing in place. Once you are done securing the top to the frame, there should be a 3 inch hang-over on the front (you want these 3 inches to attach clamps for your work projects). Nail or screw top into the frame.
The remaining piece should be cut in half and trimmed to fit, cut notches where it meets the legs, and trim the 3 inches so it fits snuggly into place. Nail to the inside supports and you have shelving on both sides of the 8 foot workbench.
Paint or varnish
Paint or varnish to protect the top, legs and sides of your workbench.