Ways to preserve your porch floor

Design options help reduce maintenance

June 20, 2008|By Mike McClintock, SPECIAL TO THE TRIBUNE

Between drifting snow and big storms that hit the house sideways, even covered porches take a beating. The hardest hit are traditional, solid surface, tongue-and-groove floors without gaps for drainage like a deck. But there are several ways to reduce maintenance and repairs when you build a new porch or maintain an old one.

Built-in problems. Flat roofs have a little slope because they have to shed water. But when it comes to porches, many contractors take pains to make the floor level. It looks right and feels right, but it's wrong, particularly for tongue-and-groove floors with no gaps. Those floors should be sloped to encourage runoff. Some recommendations call for quarter-inch per foot, which translates to a noticeable 2-inch slant over an 8-foot span. Many builders use 1/8-inch per foot -- enough to move puddled water that could seep into joints and rot the floor, but not enough to roll hot dogs off your picnic table.

Design options. If you're building (or rebuilding) a porch, consider this hybrid of a 2-by-4 deck and a closed-seam floor. The idea is to treat the porch like a deck with gaps between boards, but use 3/4-inch-thick lumber that's more finished looking than larger lumber. Sure, you could use pressure-treated 2-by-6s with liberal drainage gaps. But that utilitarian combination might look a little rugged for a porch. The downside of using 3/4-inch-thick lumber is that it needs more structural support than 2-by-4s, typically joists spaced at 12-inch instead of standard 16-inch centers. That means some extra lumber and framing work. But the 3/4-inch surface will feel at least as solid underfoot as rows of 2-by-4s.

Different fasteners. Hidden clip systems such as Ipe Clip, Deckmaster and others require more time, attention and money than nails or screws. But they create a sleek surface free of fasteners. Most systems (for wood and synthetics) attach clip hardware to the joists and then lock the deck boards to the fasteners. At 50 cents or so a pop, using hundreds of hidden fasteners can add up. If you're paying a contractor the extra installation time will cost even more. Workers can't just plunk down boards and fire away with pneumatic nail guns.

But hidden clips are a slick construction detail that also reduces maintenance. There aren't any water-collecting holes where nails have been shot in too deeply. And there aren't any popped nail heads to trip on. But if you're springing for cedar, redwood or some other great-looking lumber, no nails is a finishing touch that really showcases the investment.

Preserving a T&G porch floor. If you want a covered porch with tongue-and-groove flooring -- and you want it to last -- consider these tips from the Southern Pine Council. Slope exposed soil underneath the porch away from the center to eliminate puddles. Reduce the upward migration of moisture by laying a moisture barrier (4-mil polyethylene), anchored with gravel.

Encourage airflow beneath the porch by using ornamental vents or lattice skirting. Slope the porch framing a quarter-inch per foot away from the house to permit water runoff.

Paint or stain. You can stain or paint for primary protection. The traditional look is a medium gray paint, as if the wood were concrete, with a slick finish even though a sand mix would make the surface less slippery when wet.

But the main trouble with paint is that you'll need so many touch-ups, plus sanding and scraping, where people walk, grind in grit or even move a chair.

Stain makes more sense because it soaks in instead of resting on the surface.

And you can choose a wood-preserving, pigmented stain from nearly white to charcoal and any shade of gray in between. It will wear, but more gradually and less noticeably than paint.