When the flooring of a home is sagging, or tiles have cracked, it is possible that the subfloor below the flooring has been damaged and is not able to support the weight of the flooring. Deciding how to replace subfloor materials entails figuring out what part of the subfloor has been damaged as well as what has caused the damage. It is possible that after deciding how to replace subfloor plywood, a major source of damage will be uncovered that will need to be fixed first.
Finding the Source
If the failing subfloor is in the bathroom, it is probable that a water leak of some kind has caused the damage. Before deciding how to replace subfloor materials, the source of the leak will have to be found and stopped.
Some places to check include the seal at the toilet joint, any floor drains, and the area around the shower. Inadequate shower curtains can cause enough water leakage to seep into the subfloor and cause damage. Another problem may be that you may need to install a new shower pan.
One tip for how to replace subfloor materials is to utilize the crawlspace for a visual inspection of damage. If the home has a crawlspace, it should be checked for any water leaks or condensation under the home that may be causing the damage. Inspecting the subfloor from the crawlspace can also help to spot any damage being caused to the subfloor from the underside. These can include termite infestation or powder beetles.
Replacing the Subfloor
If it is a small section of subfloor that is found to have damage, the damaged section should be replaced with new plywood, replace that section with new plywood. The old section can be cut out with a circular saw and a new piece put in its place. One important point in how to replace subfloor is to make sure the new piece is precisely the same size as the old piece to ensure a tight fit that will support the flooring.
If the entire subfloor is damaged, there are a few options available regarding how to replace subfloor wood. The entire subfloor can be removed and replaced with new wood, which is a costly and time consuming venture.
It is also possible to purchase new subfloor plywood and nail it directly over the old subfloor. This may not be a good idea if the old subfloor has water damage and could mildew or cause a mold problem. But subfloors that have simply worn out from age may benefit from this method, which is a much faster and easier method.
Plywood is generally available in 4 ft by 8 ft sheets. Make sure to purchase enough sheets to complete the job by calculating the square footage of the subfloor to be replaced, and then add a few square feet to anticipate some waste when the wood is cut. Some home improvement stores sell plywood sheets that are made specifically for subfloors.
Different types of subfloor wood will have different recommended placement over the joists, so those instructions should be consulted when deciding how to replace subfloor wood. Many wood types require that it be installed at a 90 degree angle to the joists, but there are some that require a more diagonal installation. Using the correct type of nails with the chosen wood is important as well. (See Different Types of Plywood)