Porch Flooring

The Structure: Footings, Joists, Bridging

Porch flooring is about what lies beneath the actual finished surface of the floor - like the footings, joists and foundation. You know, the structure, anatomy and foundation.

I even narrated a short slide show below of our son's porch as the floor was constructed.

If you are looking for ideas to finish your porch floor (the part you see), then visit our porch decking section for ideas on the actual floor covering.

Anatomy of Flooring

If you are building a new porch don't skimp on its foundation. A well-constructed foundation will result in a long-lasting porch. Extra care in both design and materials is necessary if your yard slopes significantly, your soil is unstable, you live in a very wet area, or if you are building on rock. The following information will address typical porch anatomies.

No matter whether you have a slab (poured) porch or it sits on top of joists, you still have some type of support. And in either case, the porch foundation will allow you to use many different types of flooring.

Above photo courtesy of taberandrew

Slab porch

Porticoes, or porch/patio floors: Typically for a porch slab floor (normally for porticoes or porch patio type floors) concrete is poured over two or more inches of gravel. The gravel layer is for drainage and to help prevent the concrete from cracking during the freezing-thawing cycle.

Local building codes determine how much gravel is required and how thick the concrete slab is required to be depending on where you live. We've lived in areas where concrete could be poured right on top of dirt (one extreme) to other locations where you needed at least 10 inches or more of gravel.

The most common type of porch deck and relatively easy to construct wood porch construction begins with footings (concrete) that extend down into the ground. The depth of the footings is dependent on local building codes. In areas with freezing-thawing cycles, building codes will require the footings to be deeper than in areas like the southwest.

The floor joists run perpendicular to your home and support the actual flooring. They are normally placed 16 inches on center.

Bridging is added between the floor joists to add strength and to prevent the porch from swaying or bouncing. Normally, bridging is only added when you have a long span.

The rim joists are floor joists that are the outer most floor joists. These are typically the only joists you will see when looking at the porch. You can also add a skirting on your rim joists. This is done to make them more appealing. Don't confuse this skirting with the porch skirting used to cover the exposed portion around your porch.

Part 1
Foundation Preparation

Part 2
Corners, Thresholds, and Rim Boards

Part 3
Squaring Your Porch

Part 4
Installing Porch Boards

Part 5
Finishing the Floor

Porch Decking - the Part You See

To finish the porch decking, trim may be added around the edges adjacent to your home's siding.

Now that you know your flooring anatomy, pay particular attention to the porch's structural components, i.e., existing porch decking, joists, rim joists, footers, and support posts.

• Make any necessary repairs before laying down a new porch floor, or painting or staining your existing floor.
• Walk across your floor to see if there is any "give" to it.
• Your floor should have a solid feel to it. If not, removing the old flooring will give you access to the framing underneath.
• Once exposed, you can replace any rotting or decayed boards, add bridging, and even add additional joists to prevent sagging or to reinforce other joists.
• Contact a local contractor if needed and remember to comply with local building codes.

Photo courtesy of J to the Nathan

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