WHAT IS WOOD JOIST SPAN TABLE AND HOW WE USE IT?

For those who have been in this field long, this table is actually a popular one. In fact, there is no building project that doesn’t use this table. Wood joist span table makes sure that we start the project in the right calculation, preventing costly problems and accident in the future. To be precise, let’s dig some more.

SO, WHAT IS A WOOD JOIST SPAN TABLE?

A wood joist span table is basically a complete and thorough table that shows the exact measurement on each wood joist for each room in a house. It shows how much load the joist could and should take. Commonly, the table doesn’t only show you the joist span measurements but also the rafters for a complete and detailed reference.

This table can be categorized as an instructive guide, helping you to make sure that you build the house with the right calculation so it will be strong enough. In US, the entire measurement is standardized. Each building should follow this standard to be able to build a strong property.

Of course, when you purchase the code book containing this table, there won’t be any step by step instruction in how to build the entire thing technically to details. Instead, as in other building code, you will continue the project following these codes.

THIS IS WHY IT IS VERY IMPORTANT

Understanding the importance of this table won’t be enough without learning on the facts about building. The following facts will show you how the table plays its role:

Wood is actually destined to be just so strong to be a solid foundation. The branches will be well supported including when the weight is added with the wind. It bends and it still supports. Learning the complexity of wood strength allows us to determine the size of rafters and joists.
Your house foundation is supposed to send out your house weight to the soil under. Meanwhile, the house will be the structural system. This system is meant to resist wind load, snow load, live load derived from occupancy and use, as well as dead loads.

In this system, your house rafters, joists, studs, and beams will be the structural skeleton of the entire system. They need to be stiff enough as well as strong enough to support all the weight, both are extremely important factors.

The maximum standard of allowable deflection will be the factor that determines the structural stiffness. Allowable deflection means the most bends rafter or joist should make within the maximum load. As for calculating the stiffness of the design values, we only use the live loads factor.
Rafters and joists need to be strong so it won’t break when it is fully loaded. It is why your material strength is extremely important. To get the minimum strength on a design value, both dead loads and live loads will be taken into account. It is totally the opposite of how to determine its stiffness.
We will need to determine the dead load value for a roof system or the given floor. To do this, we need to add all together the given components installed materials. The weighs of carpet or underlayment, sub floor, floor joists, strapping, drywall, and more. All details are already accounted for and added in the list of the span table.

WHERE TO GET IT AND WHAT TO LOOK FOR

So, where can we get this table? Basically, it will be included in a code book, as mentioned before. The AWC or American Wood Council actually issued these code books, and you can get these directly from them. While the tables are complete, it is easy to follow as well.

In alternative, you can also purchase these code books online, which are available widely, or from your local code official. It is practically easy to get with so many providers are offering many options.

If you plan to get one makes sure to get the spans for joints and rafters code book. It tells you the exact number of E and Fb combinations spans. Next, considering that you will use lumber in many variations of dimension grades, sizes, and species, you will also need a copy on joists and rafters designs values book.

While AWC is a great provider for these tables, you can also opt from other providers. The alternatives are endless, including Western Wood Products, Southern Forest Products, Canadian Wood Council, and many more. Search and find one that fits your area and condition best. It doesn’t matter where you get it, as long as you get the copies and follow it as you should be.

STEP BY STEP: HOW TO USE THE WOOD JOIST SPAN TABLE

So it is pretty clear now that the particular table is really a mandatory in this field, and using it will be a must. It can be a little challenging at first, but the following steps are the appropriate and right way to use it:

Check your plans, and then determine the conditions of your designs, including the on-center spacing and span.
Look on the table and check on the codes for deflection, dead load, snow load, and live load allowed.
Choose the right and appropriate table among your entire options. Recheck your pick.
Match your design condition to the span table of your choice. Then check on the Fb and E minimum values mentioned in the table. In here, you will also options for size and on-center spacing.
Check on the design values table and read on the list. Choose the lumber you are going to use from this list while considering the entire codes. In here, you will also have options for grades and species of your lumber for even economic preference.
Check on your table, and then find the design value of your grain. Next, match this design value to the needed compression perpendicular.
Now, you need to verify. Make sure that the lumber species you choose in fifth step meets the entire design requirements as listed in table in sixth step.