Load Bearing Shims

Load Bearing Shims

Load bearing shims are thin and often tapered wedges made of wood or plastic, traditionally used to fill small gaps or spaces between objects providing stability. Load bearing shims are typically used to support, adjust for a better fit or provide a level surface. As indicated in the name, load bearing shims are designed to be able to support a particular load or weight. For this reason, ones manufactured from plastic or similar materials such as rubber are better as they are constructed to support a specified load. In comparison, wood ones rely on the composition of the wood used and the moisture content within the wood which does not allow for an exact load bearing capacity.

The main reason one uses load bearing shims when constructing a stone deck or patio is because nothing is ever perfect. The products you are dealing with are not “Mil-Spec” designed to exact and precise tolerances. Load bearing shims not only help you to ensure everything is straight and aligned as you need it to be, but are capable of supporting the heavy loads of the stone you will be using. They are perfect for leveling paver or porcelain tile or ensuring your subfloor is perfectly flat when your framing materials are a little less then desirable.

Depending on what you are trying to accomplish you can install the load bearing shim and use the pressure of the materials being shimmed hold it in place. Put a fastener, such as a screw through it, or use of construction adhesive to hold it in place. As mentioned before, not only are plastic or rubber shims better at supporting an exact load, they will also not crack and split when a fastener is driven through as would happen with a wood shim.

Also, if wet or damp, wood shims will not adhere to the construction adhesive if this is your preferred method of installation.

Most tapered plastic or rubber shims on the market are scored at predetermined locations allowing you to break them off as needed at the required shimming space. Typically, wood ones you need to score yourself and break off. Also, the plastic or rubber load bearing shims are not affected by moisture or other environmental conditions that can cause wood ones to swell up or shrink and deteriorate over time. One of the better load bearing shims on the market is the EZ-Shim, they are manufactured in the USA and have a load bearing capacity of 8,000 lbs psi.

You can even find round load bearing shims that can be easily snapped apart into quarters and stacked up as needed. Bison Innovative Products manufacture two such shims; the B11 is a 1/16² flexible rubber shim, while the PS1 is a rigid 1/8² shim. These types of load bearing shims are ideal when trying to level larger stone pavers or porcelain tiles. If you are working with a rooftop deck and using any of the pedestal systems on the market, the use of round shims that can be broken apart into halves or quarters is particularly useful.

In a perfect world all your construction materials would be straight and true, but we all know that is never the case. So, whether you are transforming your wood deck into a stone deck or building a new one, creating that beautiful maintenance-free rooftop patio or laying that stone deck patio, using a quality load bearing shim will not only save you time and aggravation but will ensure your project comes out straight, level and will last a lifetime.