Steel Manufacturing Blog: Keeping it Steel

Plastic Shims: Solid and Scored

Posted on Wed, May 13, 2015 @ 03:59 PM


For the construction trade, plastic shims are an essential tool but care must be taken to assure they are rugged enough for the intended use. Before even considering the compressive strength of a plastic shim you must first ensure that is it should be solid with uniform plastic throughout. Lower cost hollow plastic shims are manufactured but do not deliver the strength or durability required for most construction projects.


The Steel Supply Company provides only solid plastic shims made from Polypropylene or High Impact Polystyrene. This produces a shim plate, a shim pack and plastic horseshoe shims with high compressive strength and durability.

Construction Shims : View Compressive Strength test results.

The result is powerful finger shims, shim plates and construction shims that withstand pressure without deflection or permanent deformation. They are intended to be used in both permanent and temporary applications.

To see a list of our shim products, click here.

Fig. 1

plastic shims
Another important characteristic of the plastic shim is scoring. Figure 1 shows a polypropylene plastic horseshoe shim that measures 6” x 4” x 1/8” thick.  Slot width for horsehoe shims of this size is .890”, to accommodate 3/4” and 7/8” bolts.  If less length is required the scored line allows the installer to quickly break off the last inch of the finger shim. This reduces the dimensions to 5” x 4” x 1/8” thick. The compromise is a reduction in compressive strength of only 1.25% when used as a 6 x 4 Shim, and zero reduction in the 5 x 4.


Fig. 2

plastic construction shims

Figure 2 shows a solid plastic shim. It also measures 6” x 4” x 1/8” thick. Unlike Fig. 1, these horseshoe shims do not have a slot. A solid shim like this one is designed to be used in tilt up concrete construction, precast cladding, plate glass Installation and any other application where the shim is not required to interact with a bolt. The scoring shown in Fig. 2 allows the installer to quickly separate the shim section to make 4” x 4” or 4” x 2” pieces. The scoring in this case reduces the overall compressive strength by 2.90%.

There are cases where plans require solid plastic shims without scoring. This is often caused by an installation situation or function that may cause the shim to inadvertently separate and lead to failure. In these cases The Steel Supply Company can provide solid plastic shims in any configuration and material required.

Tags: Shims, Shim Plate, Shim Pack, Construction Shims, Plastic Shims