Make sure you also buy the same type of joist. If your floor joist is an I-joist, for example, buy an I-joist. If you’re not sure what type of joist you have, take pictures of one from several angles and show your photos to an employee at your local home improvement store. An I-joist consists of 3 parts: a horizontal piece of lumber on the top, an identical piece of lumber on bottom, and a central web in between, which is usually made from plywood.
Be sure to wear protective eyewear to protect your eyes from flying sawdust and woodchips. Also, wear a dust mask to protect your throat and lungs from wood dust. After cutting the web away from the top flange, put it somewhere where it won’t be underfoot.
Remember to wear protective eyewear whenever using an electric saw. Be sure to insert a wood-cutting blade into your reciprocating saw before cutting wood.
Use the back end of a hammer or crowbar to help open the gap between the floor joist and subfloor. Insert a wood-cutting blade into your saw when sawing through wood, and a metal-cutting blade when sawing through nails. This process is quite difficult and will take some time and muscle. Be patient and experiment with using different tools to see which ones work best. Once the joist is completely detached from the subfloor, put it away somewhere where it won’t be underfoot.
Be sure to apply the adhesive just before you put the joist into place. If you apply the adhesive too early, it may dry out by the time you move the joist into place.
Tap the joist into place with a hammer. You’ll need at least 1 other person to help you install the new joist.
If the jack doesn’t move the subfloor up high enough for you to slide the floor joist in, try using a larger jack that’s able to bear a heavier load.
Look for joist hangers at home improvement stores and lumberyards. You can find joist hangers to support I-joists as well as standard wood joists.
