How much weight can a floor hold. Figuring out floor joist load capacity is best left to a structural engineer.
They must take building code requirements and the structural properties of wood into consideration before determining concrete numbers.
While you can speak with an engineer about your existing floor, it’s important you know the basics in order to help you address and understand your own specific construction project.
How much weight can a floor hold
The IRC, which was developed by the International Code Council (ICC), dictates that residential buildings must support a minimum of 40 pounds per square foot.
Since sleeping quarters are often located on upper levels, the flooring in these areas must be able to support a load-bearing capacity of 30 pounds per square foot.
This article will examine some of the ways you can make sure your dining or kitchen floors meet or exceed local requirements so as to provide the necessary stability and reliability.
Kinds of Weight Loads
We’re going to touch upon two kinds of loads. Live loads include furniture, people, and anything else that the floor has to support but isn’t permanently attached.
The dead load on the floor is how much weight the floor can support without any threat of collapse and I always like to use this example to showcase how important it is to know what you’re getting into before you start working with a certain material.
For example, imagine there is a 50-pound box on the ground and also one that weighs 100 pounds, which will eat up more energy.
If people walk over a floor from time to time it makes sense that they should have durable and strong floors in order for them not to worry about falling through and injuring themselves.
Because if something heavy happens to be crushed towards the middle whilst walking over it would lead to an even bigger problem that just normally breaks down how smooth your path forward would wind up looking as well as how attractive your finished product will look.
So we want your living spaces to look good and there’s no way that can happen if you don’t pay attention to details.
The Span Tables and the Design Values
Tables that show the span tables and design limits for particular lumber types allow you to determine whether a given floor design will meet code and design requirements.
For a given joist size and spacing, the tables indicate the strength value, called the Fb value, and the stiffness, called the E value, of the joist.
Architects and engineers use these tables to determine the required size and spacing of joists as they design buildings.
But it is important to work backward when using them because they will also tell you how much weight your wooden floors can hold.
Calculating the Load Limit
First, you need to determine the size, the spacing and span, and what species and grade of lumber you are using in your joists. Next, you need to look for a stamp on the joist that indicates what species and grade it is.
You can then consult a design value table to find the Fb value of that material as an example if it was a 2 by 6 Douglas Fir-Larch joist with a live load of 30 PSF and a dead load of 10 PSF we would look up the number 1 grading in a 2 by 6 Douglas Fir-Larch joist tested at 16 inches on center.
This would give us an Fb value of 1,495 pounds per square inch. From there we have determined that this product meets our design requirements so we may proceed with our floor installation.
We now know that this product meets our design requirements to support our regular residential living conditions.
You can find out how strong your joists are and what kind of loads they can support! Just take a look at the span tables below to see what we mean.
If you live in a two-story home, you’ll want to use both the top and bottom tables to figure out the maximum load that your floor can hold.
Simply find an equivalent live load (noted in black type) that matches the total of all floors living on your building and compare it to your existing Fb value.
In this example, the illustration shows that one should not exceed a combined 40 PSF packed download or 10 PSF spread over an unpacked area.