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.

The life expectancy of deck boards varies widely based on the material, climate, and maintenance. Untreated wood boards typically last 10 to 30 years with proper care, while pressure-treated boards can last up to 50 years. Hardwoods generally outlast softwoods. Composite boards also tend to last longer than natural wood. Environmental factors like arid or humid climates can shorten a deck's lifespan. To extend the life of wood decking, it's important to consistently clean and seal it to protect against moisture, UV light, and insects.

Yes, you can build a deck over your outdoor HVAC unit, but you need to leave at least 5 feet of vertical clearance above the unit. If you don’t want your deck to be that high off the ground, you could build a floating deck in another part of your yard—again, as long as you leave at least 4 feet of horizontal space between the deck and your AC unit.

No. In most cases, it’s not colder or freezing temperatures that affect decking materials but the amount of moisture that seeps into the materials as a result. For example, wood decking material is more likely to suffer from rot or decay when exposed to excess moisture from snow or ice. An extreme change in temperature can cause wood to expand or contract, but only if it’s not properly treated beforehand.