Floor Support Joists

Span tables and tables that show design limits for particular lumber types allow you to determine whether a given floor design will meet code and design requirements.

Floor support joists.

In some cases additional joist supports will have to be installed before there can be extra heavy objects on the floor. The wall could be either a properly sized structural concrete or concrete block wall or a wood framed wall. If you have sagging cracked or twisted joists which can happen in older houses this project will provide the extra support the floor needs. Once we go beyond the allowable spans for floor joists as shown in the floor joist span tables we will need some kind of support under these floor joists.

The joist support helps reinforce the floor so it can handle the weight load it needs to. This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction. According to section r502 4 of the 2009 edition of the international residential code joists under parallel load bearing walls must be big enough to support the weight of the load they bear. Span tables use these tables to determine rafter span ceiling joist span and floor joist span.

Here we ll examine the rules. Plenty of trial and error plus a healthy dose of engineering and testing have gone into the official rules in the building code. This is especially true if you are planning on getting a grand piano or something of the same caliber. We ll discuss these.

This support could take the form of a structural wall.