Anyone have a Span Chart?

I know that determining the span of floor joists is a complicated issue - type of wood, load, etc. but does anyone have a general “rule of thumb” span chart?

2x6 8-9 ft
2x8 11-12ft
2x10 12 - 16 ft
2x12 16-20 ft.

based upon 16" on center…great spacing then spans will be reduced…the above are
just that…rule of thumb.

Here is a basic (general) chart. As stated there are other considerations reg. loads (imagine a hot tub or spa on a deck for instance).


Here is a basic joist span chart.

You can also go here and print it out.
I carry the US Span Book for Major Lumber Species of which I got free.
Can not find the website to save my life but its out there. (you may have
to be a builder to get it free…not sure any more).

Rule of thumb could get you in trouble depending on who’s thumb you are using.
Span charts such as this one and the ones above should be followed.
The IRC span tables is the minimum requirement allowed by law in Jurisdictions that have adopted the Code.
References to Manufactures such as this should enable you to stay above those minimums.
There are others available depending on the species of the wood being used and the type of floor construction that may increase the dead load above the 10 psf that these tables indicate.
Personally, I would never go beyond a 16’ span for a 2"x10", but is allowed on certain types of species.

Best left to a designer to calculate the loads than making an assumption that might be wrong. :):smiley:

Also, most the grades of lumber you will come across in construction is Nbr 2.
I have not seen any one use select.

I joist have their own spans and those spans do not go across the board of other manufacturers. TJI, BCI, LPI, etc… often differ in spans due to the series and type of I-joist they use.


Great info - Thanks guys. I can always count on iNachi! :slight_smile:

For Canadians this is an awesome book. It is currently referenced in the 2006 Ontario Building Code. It is the Span Book from the Canadian Wood Council.](

Bill -

  1. Why don’t you just get out your Code Book?

  2. Many lumber yrds give out little pocket size books with spans.

LOL - After a few of the guys sent me some charts I realized that the info was in the IRC. Some of the charts they sent were simplified, and that was what I was looking for.:slight_smile:

here’s a calculator