Concrete – it’s one of the most ubiquitous building materials on earth. And yet, fully utilizing this building material can be challenging for many DIYers. That’s primarily because concrete requires a builder to carefully plan out everything from how their concrete is mixed to where it is poured.
To that end, many DIYers struggle when it comes to implementing a proper concrete form.
If you’d count yourself among that crowd, then fear not. You’ve come to the right place to learn how to make a concrete form successfully.
How to Make a Concrete Form
While later on, I’ll also cover the alternatives, let’s start by taking a step-by-step look at how to create a concrete form from wood.
Step 1: Gather Supplies
To begin, you’ll want to gather up all of the tools and materials necessary to successfully execute the construction of a standard concrete form.
In particular, you will need to gather up some 2×12 boards that are cut to the length of your desired slab’s dimensions. If you cannot obtain single boards of that length, you should consider splicing a couple of shorter boards together with nails.
Next, you’ll want to pick up some wooden stakes. The precise number needed will vary based upon the size of your form.
As for tools, you’ll want to have a saw, a hammer, a level, a measuring tape, a plumb bob, and a line level (with line) on hand. As always, you should also come prepared with proper personal protective equipment appropriate to the conditions of your worksite (such as ear, eye, and mouth protection).
Step 2: Set and Level One Side
Once you’ve gathered all of the necessary materials, you can begin by staking out the corners of your future slab. Once you’ve determined where your corners will be located, mark them with long stakes.
From there, grab one of your long 2×12 boards and align it with two of your corner stakes. With the help of an assistant, level this board out before nailing it to the corner supports.
Step 3: Brace the Side
Once your first form side is in place, you’ll need to brace that side to prevent movement (especially once the force of the wet concrete pushes up against it).
To do this, you’ll want to cut some scrap wood planks (that aren’t going to be used as mold sides) to a length equal to your side board’s width plus a couple of inches. You’ll want to make enough of these cut planks such that two could be placed every 2 feet along the board’s length.
Once you have these cut planks available, use your hammer and begin to pound one stake into the ground flush with the outside of your sideboard. Be sure to do this in a manner that does not cause the sideboard to bow inward.
Once that is done, come back and place another plank at a 45-degree angle to the top of the first support plank. This will create triangular support that can more efficiently buffer each section of the sideboard.
Step 4: Repeat for the Other Three Sides
After completing your mold’s first side, repeat the process 3 more times in order to successfully create a 4-sided slab mold. (If you are creating a mold of another shape, repeat as many times as necessary.)
As you go along, be sure to carefully utilize your several leveling tools to ensure each corner and side is level with their opposite corner or side.
If you notice one or more points falling out of line, don’t be afraid to make modifications. These changes will pay dividends when it results in a level and square concrete slab.
How to Make a Curved Concrete Form
Many DIYers and even some professionals scratch their heads when it comes to making a curved concrete form. After all, a standard concrete form can only make square-shaped slabs.
Fortunately, modern concrete contractors have come up with just the tool to make creating curved concrete surfaces a breeze – a flexible plastic form system.
In essence, these systems consist of specialized plastic lengths that can be positioned into non-linear forms. This is done using a specialized stake that comes with the system that allows a user to lock in a specific form without needing any specialized tools.
These forms are also reusable, making them a major asset for contractors.
This video will give you a better idea of what these forms look like and how they are used:
Alternatives to Wooden Concrete Forms
A wooden concrete form can often do the job when it comes to making a flat slab.
However, if you’re planning on making a lateral concrete structure (such as a support post or anchor), you won’t be able to rely on a wood-based mold. Instead, you’ll want to reach for a Sonotube which is a specialized cardboard concrete form that contractors and DIYers today both use regularly.
Using a Sonotube is not hard at all. In essence, they simply require you to place the tube, fill it, and then peel it away once the concrete sets. Though bracing can be used, most uses of a Sonotube don’t require them at all.
As such, they are a simple, cost-effective alternative to wood concrete forms through and through.
As you’ve seen, making a concrete form is not so difficult of a task after all.
In the long run, the hardest part of making a standard form of this kind lays in keeping it square and level throughout the construction process.
But if you have the right materials and follow the steps listed above, you’ll find yourself better able to complete concrete-related jobs on your own in no time at all.