Concrete slabs are commonly used for patio surfaces because they are relatively inexpensive to install and are very durable. Many homeowners take an extra step by adding overhead protection to this concrete slab, such as an awning or patio cover. This step generally requires installing support posts, and you must use the proper installation methods to ensure each post stands firm and straight under the weight of the patio cover.
Do a Plumb Job
One of the most important considerations for placing wood posts on a concrete slab is to make sure they are level and plumb. A carpenter’s level or a laser-type leveling device is useful to ensure a straight and plumb installation of wood posts. It is best to level and plumb wood posts after placing each post into its secured mounting bracket. However, it is important to take this step both before and after fastening the bracket to the post to ensure the posts are indeed level and plumb.
Common Mounting Bracket
The most common and readily available type of post mounting bracket is a U-bracket. This is a steel piece of hardware that comes with pre-drilled holes for fastening the bracket to the concrete slab as well as for fastening the bracket to the post. The U shape of this mounting bracket provides an ample footing for wood posts and creates a solid and sufficient fastening area on the bottom of the posts themselves.
Three-Sided Mounting Bracket
Another reliable type of bracket for mounting wood posts on a concrete slab adds yet another fastening surface on the posts. This bracket provides perhaps the most secure support for wood posts on concrete, while still allowing you to make level and plumb adjustments if necessary. Three-sided brackets of this type are also pre-drilled for both post and concrete slab fastening. As with all post mounting brackets, it is critical to use masonry bolts when fastening the brackets to the concrete slab.
Additional Steps to Take
All wood structural members, including patio posts, should be protected from environmental elements. Moisture is the most important factor to consider, whether the moisture comes from precipitation, lawn and garden sprinklers or even from humidity. Pressure-treated lumber and galvanized fasteners are highly recommended for exterior wood applications, and especially for wood posts on concrete slabs due to the likelihood of moisture coming into contact with both the slab and the patio posts.