Measure the side length of the boards

How to Build Formwork for Concrete Base

A pedestal is needed in the house for the new heat pump. It has to be stable, but otherwise, it can remain simple. So it makes sense to create the whole thing yourself. The easiest way is to pour the concrete base. But how does it get the right shape? With formwork, of course! In the following instructions, we show how to build a workable formwork for a concrete base.


Check the construction of the concrete base on the plan

Our new heat pump shouldn’t just stand around in the landscape. Instead, it deserves a decent base in front of the house, complete with a drainage pipe. Since stability is more important here than aesthetics, we can also pour the concrete base ourselves. All we need is proper formwork.

Fortunately, it doesn’t take much to build the formwork for a concrete base of the size you need. With the materials, you can even make do with leftovers from other projects. However, it would be helpful to create a construction plan beforehand so that the base, heat pump, and installation site really harmonize.

Determine the height of the formwork


For the first steps, you need a straight edge, a tape measure, pencil, measuring square, and a circular saw. We use a two-meter long and 50 cm wide shuttering board as a material basis, which we want to divide into four smaller boards. These boards will later serve as the side parts of the rectangular formwork.

Draw the transverse axis with an angle

First, we mark the center point on the 50 cm long sides of the shuttering board. From here, we draw the longitudinal axis of the board with the help of the straightedge. So we get two halves, each 25 cm wide. Then we measure 68 cm on the long side and draw a transverse axis over the board with the angle. So we get a total of four parts: two 68 cm long, two 132 cm long. Use the circular saw to cut the formwork board along the lines.

Cut the formwork along the longitudinal axis


Screw in two screws at each corner

Now we have four fully sealed side parts for our formwork. With their width of 25 cm each, they determine the height of the future base. Now to build the formwork for the concrete base, the boards only have to be screwed. So the side parts are arranged in such a way that the shorter boards rest on the front sides of the longer boards.

In this position, holes for the screws are pre-drilled with a cordless drill, through the shortboards into the end of the longboards. Then the screws can then be screwed in – two at each of the four corners.

Note: At this point, make sure to use wood screws of sufficient length. After all, the formwork shouldn’t fall apart.

If two of the sides are a bit too short, as is the case with us, wooden panels cut to size can be inserted as intermediate pieces when screwing. So we have enlarged our long sides by 3 cm each.

Nail down the first triangular strip


The body of the formwork would already be finished. However, we want to improve the design a bit and provide the base with a bevel around the top. To get this, we will mount triangular strips on the inside of the formwork at the top to bend the shape here.

Miter cut the next strip

The first triangular bar is measured exactly on one of the long sides, and the endpoints are marked. Then we put the bar in a miter box and cut the endpoints to 45 degrees. Then we pre-nail the bar by tapping the nails lightly into the bar at regular intervals. This makes it all the easier for it to be attached to the inside of the formwork.

Tip: It is extremely helpful to tap the tip of the nails with a hammer. This makes the nails dull and has less of a tendency to split the delicate wood of the strips when hammering in.

It continues with the second bar. We now hold this to the narrow side of the formwork and take the natural dimensions. After the endpoints have been marked, we miter the bar here again. The bar is pre-nailed and then attached to the upper edge of the inside like its counterpart. The same is done with the remaining two pages.

Finally, we measure four shorter strips for the inside corners of the formwork. However, these are not mitered but cut straight. Then they are mounted in the corners as shown so that there are no sharp edges here either when we make the concrete base.

Finished formwork with concrete base


And the first step on the way to our new concrete base has already been completed. In fact, it doesn’t take much to build proper formwork for the concrete base. So you shouldn’t imagine too big obstacles here.

Last but not least, a tip: The intermediate pieces with which we have extended the long sides of our formwork are not sealed, unlike the parts that we obtained from the formwork board. To prevent the concrete from drying out, these sections should be treated with a formwork oil. After that, however, we can continue, and we can pour the concrete base.

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