Floor Support Joists

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.

Floor support joists.

Still when framing a raised floor it s easier to think of floor joist spacing in terms of 12 16 or 24 inches on center because each joist is positioned along the header according to its center point. 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. This article provides step by step instructions and pictures on how to make structural repairs by sistering floor joists alongside weak joists.

Span tables use these tables to determine rafter span ceiling joist span and floor joist span. 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. This is especially true if you are planning on getting a grand piano or something of the same caliber. In some cases additional joist supports will have to be installed before there can be extra heavy objects on the floor.

This support could take the form of a structural wall. Plenty of trial and error plus a healthy dose of engineering and testing have gone into the official rules in the building code. Here we ll examine the rules. The joist support helps reinforce the floor so it can handle the weight load it needs to.

We ll discuss these.