Get matched with top deck repair pros in Philip, SD

Composite decking requires a solid foundation, substructure, or subframe to ensure stability. This base is typically composed of posts, beams, joists, and footings. The frame's joists can be built from various materials like composite, plastic, timber, or metal, as long as the base can support the deck's weight without shifting. A professional deck builder might recommend installing the frame on a solid concrete base for added durability. The final design and materials for the substructure will depend on your budget, the type of deck, and environmental conditions.

For a 12x20-foot (240-square-foot) deck, you can expect to pay between $7,200 and $14,400. This cost is based on a general price of $30 to $60 per square foot. The final price will depend on factors such as the decking material, design complexity, deck type, location, and local labor costs. Keep in mind that add-ons will increase the total; for example, adding an under-deck drainage system to a deck of this size could cost an additional $7,700.

Staining and sealing the underside of a deck creates a moisture barrier but traps water in the boards, quickly leading to rot. No matter how well you seal the above deck, water still gets through via nails and screw heads on the surface. Allow this water to flow naturally under the deck, where it is routed through the drainage system.

In general, you need a footing at each corner of your deck, and within 8 feet of each other. So, how many you need depends on the size and shape of your deck, plus any local building codes. It also depends on factors like the load capacity of your soil and the weight of your deck. You can find a footing calculator online or contact a pro for support.