Wooden Concrete Forms: Best Wood, How to Build & More

Wooden Concrete Forms: Best Wood, How to Build & More

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If you are planning on pouring your own concrete, then you obviously need to create forms to hold that concrete in. Concrete is liquid when still uncured, so it needs a form to hold it in place as it dries and cures.

The best way to build a concrete form is with wood, but what kind of wood do you use? Today, we’re going to tell you what the best type of wood is for this task, and we’ll then take you on a step-by-step tutorial on exactly how to build a concrete form out of wood.

What Is the Best Type of Wood to Use for Concrete Forms?

If you plan on creating your own concrete forms, you have two main options at your disposal, which include plywood and real timber. Now, plywood is obviously going to be the cheapest option here, so if you are looking to save some money, this will do just fine.

However, do keep in mind that plywood is not all that strong or thick, so if you are pouring a lot of concrete, more than just a very small slab, it will likely be too weak to hold in the concrete and might break.

Therefore, the better option to use here is usually solid lumber. With that being said, solid lumber is of course very expensive, so you do need to be careful in terms of which types you use. Generally speaking, pine, spruce, and fir are the three best concrete frame options to consider.

This is because all three types of wood are softwoods, and are therefore relatively inexpensive, yet still have a fantastic strength-to-weight ratio. This type of lumber, whether spruce, fir, or pine, should be able to resist the weight and pressure that will be created by the hundreds of pounds of concrete within the frames.

Many people also ask if it is better to make concrete forms using wooden walls or wooden steaks. However, this is a bit of a trick question, because you actually need both. First, you put stakes in the ground marking the corners of the concrete form, then you use wooden walls or sheaths to create the perimeter, and then you drive more stakes on the outside of the concrete form to keep the wooden sheaths in place.

How to Build a Wooden Concrete Form

Now that you know what the best type of wood is to create a concrete form, let’s go through a quick step-by-step tutorial on exactly how to do this.

Step 1: Measure and Plan

First, you have to determine how large the concrete form needs to be, so measure out your dimensions and then mark them on the ground as needed. All you should need for this is a measuring tape.

Step 2: Drive Stakes and Create a String Perimeter

Once you have planned everything out and determined the dimensions of the concrete form, you can then take some sharpened stakes and drive them into the ground, one at each of the four corners of the form. This marks the corners of the perimeter.

You then need to tie some string to all four of the stakes, from one to the other, therefore forming a perimeter of string connecting the stakes to each other. Make sure that the string is placed higher than or on par with the walls or sheaths that you will be using.

For example, if the form uses 2x4s, with the long side facing up, then the string needs to be at least 4” off the ground.

If you want to be extra careful, you can always level out the string to make sure that it is even from one stake to the next. This way, you could technically place the boards or walls down and line them up with the string.

Step 3: Lay Down the Wooden Boards According to the String

You now want to take your 2x4s and lay them down underneath the string, thus forming the four walls of the concrete form. Make sure that the corners are all perfectly square and that the boards line up with the string. Take a rubber mallet and very lightly hammer the boards down to ensure that there are no gaps between the boards and the ground below.

Step 4: Screw the Wooden Frame Together

Take some relatively long screws, at least 3” long, and use at least four in each corner to secure the four boards together that will form the perimeter of the concrete form.

Step 5: Place Stakes on the Outside of the Wooden Frame

To ensure that the concrete frame is able to bear the weight of the concrete that is to be poured into it, you want to take sharpened wooden stakes and drive them into the ground outside of the frame that you have built. Make sure that the stakes touch the frame, and be sure to place them at least every 3’ along the outside of the perimeter, paying especially close attention to the centers of each of the walls.

Step 6: Nail the Stakes to the Wooden Frame

Once the wooden stakes have been hammered into the ground outside of the frame, nail them to the wooden frame, making sure that you don’t use nails that will penetrate all the way through the frame, as you don’t want those nails embedded in the concrete.

Step 7: Pour the Concrete

Your concrete form has been built and you can now pour the concrete.

Once the concrete is poured, you should leave the forms on until the concrete cures and then remove them. For more information, read my articles about when to remove concrete forms and whether you can leave wooden forms in concrete.

3 Alternatives to Wooden Concrete Forms

There are three alternatives to using wooden concrete forms that we want to take a quick look at.

1. Rapid Form Bracket

The rapid form bracket is a special kind of form designed specifically for pouring elevated slabs of concrete. This form is made out of powder-coated steel.

While these are initially more expensive than wooden boards, they are reusable, so you don’t have to keep buying new boards for more concrete forms. It also takes about a third as long to set these up and take them down than a traditional wooden frame. This is something you’d get for long-term professional use.

2. Insulated Concrete Forms

We then have insulated concrete forms, which are special panels used to form walls into which concrete is then poured. These are relatively expensive, and yes, they are permanent, or in other words, they stay there once the concrete has been poured and cured, therefore forming an outer wall to the concrete.

These are often used in homes and large buildings, as they help to insulate homes, and therefore cut down on heating and cooling costs. That said, you do of course have to keep buying new ones when you pour more concrete.

3. Fabric Forms

Another option is the fabric concrete form, a sustainable and more eco-friendly option to consider due to its low footprint.

Using fabric to make a form can be beneficial because it is flexible and allows for irregular shapes to be made, plus it is also strong, reusable, lightweight, and cost-effective. Fabric concrete forms also allow water to exit and the concrete to breathe.

4. Sonotubes

Lastly, for smaller concrete slabs used for footings, you can also consider using Sonotubes. These are cardboard tubes that you can put your post into and then pour the concrete into. I wrote more about Sonotubes here.

Mistakes to Avoid, Tips & Tricks

Let’s go over a few tips to help make this process as easy and successful as possible:

  • If pouring a very large slab, consider using 2x6s, 4x6x, or 4x4s, as they’ll be able to bear more weight.
  • Make sure that there are no gaps, whether between the boards at the corners where they are joined or between the boards and the ground. You don’t want your concrete spilling out.
  • Always take proper precautions when working with concrete, as it is a corrosive substance.

Summary

As you can see, making a wooden concrete form is quite easy and straightforward, although there are also some alternatives to wooden forms to consider.