What flooring is right for a porch or deck?

expert EXPERT April 26, 2007

Porch floors are usually tightly fit tongue-and-groove, one-inch- by-four-inch planks. Porches have roofs that protect the floors. A porch floor system is tight and sheds rain.

Decks don't have roofs, so the deck boards see more water than porch flooring. Deck boards are usually 2 x 4s or 2 x 6s spaced roughly 3 .8 inch apart. Decking allows the rain to pass through. Decks allow wetting of the joists and beams below, and this helps to explain why decks usually do not last as long as porches. While porch boards may have to be replaced, the joists and beams are usually protected. Porches benefit from their roofs as well.

On old porches you may find canvas roofing. These roofs were used where foot traffic was anticipated (which is why we are discussing them here). The canvas could be over wood or concrete. The canvas was laid in 30- to 36-inch-wide strips over a bed of paint or linseed oil and lead.

Edges were overlapped by about two inches. Nails were used to secure the canvas typically 3 .4 -inch-long copper. The canvas was painted after installation. Painting was recommended every two to three years.

Most canvas duck roofs have been replaced. If you have one, it is probably near the end of its life.

Some porches or decks have concrete floors. These may be steel reinforced and are usually poured onto wood forming or a steel pan. The slab is supported by the house wall on one side, and by masonry posts or masonry walls on the other sides. Concrete floors should not be supported by wood. A concrete floor surface should slope away from the house walls. In some instances, a cold room, cellar or storage room is built below a concrete porch. This is common in northern climates where excavation is needed to get footings below the frost line.