Porch Flooring: Wood vs. Composite, Slope and Installation
Updated · By the Roof to Footing editors
Porch flooring is the tongue and groove boards or decking that cover a covered porch. Traditional porches use painted tongue and groove fir, pine or mahogany laid tight with no gaps, which looks finished and keeps dirt and drafts out. Composite and PVC porch boards now come in tongue and groove profiles too, with no painting. Whatever you choose, porch floors last when they're sloped to drain, run toward the edge and ventilated underneath.
Material options
| Material | Look and feel | Upkeep | Notes |
|---|---|---|---|
| Douglas fir, vertical grain | Classic painted porch | Repaint every few years | Traditional choice; prime all sides |
| Southern yellow pine (treated or untreated) | Painted | Repaint; treated needs time to dry before paint | Budget option |
| Mahogany and other tropical hardwoods | Rich, can be oiled or painted | Oil or paint regularly | Very durable; higher cost |
| Composite tongue and groove | Wood-look, no paint | Wash | Check slip resistance and heat in full sun |
| Cellular PVC porch boards | Painted look, very stable | Wash | No rot; good for low-clearance porches |
Board direction and slope
- Run boards perpendicular to the house, from the wall out to the porch edge. Water then runs along the grooves and off the edge instead of pooling against the house.
- Slope the floor away from the house, about 1/8 to 1/4 inch per foot. A level porch floor holds water at every joint.
- Overhang the edge an inch or so with a rounded nose, or finish with a nosing board, so water drips clear of the framing.
Protect the wood
- Prime or seal every side, including the tongue, groove, back and every cut end, before installing. Unsealed backs and ends soak up moisture and the boards cup and rot.
- Let treated lumber dry before priming; it can take weeks or months depending on the treatment and climate.
- Blind-nail through the tongue with stainless or galvanized nails so heads are hidden and protected.
- Paint with porch and floor enamel made for foot traffic, with a non-slip additive on steps.
Ventilation underneath
Most rotted porch floors rot from below. Moist air under the porch soaks into the boards. Keep at least several inches of open space under the framing, use lattice or vented skirting instead of solid panels, and make sure the ground slopes away so water doesn't collect under the porch. Over a damp crawlspace, lay a ground cover of plastic and gravel.
Composite and PVC tips
Composite and PVC boards expand and contract with heat more than wood. Follow the maker's end-gap and fastening rules, and check whether the product is rated for covered porches, open decks or both. Some dark composites get uncomfortably hot in full sun.
Railings and trim
A new porch floor often comes with new railings. If yours are more than 30 inches above grade, they need to meet guard rules; see cable railing kits for the 4-inch sphere rule that applies to any style.