Hi everyone,

I am remodeling a recently bought home. One of the upstairs rooms is a game room and I plan on putting a pool table in it.

The original floor joists were 2x6 16" OC - I glued and nailed another joist on to existing joist - so now it is 4x6 14" OC. If I would add another joist in between, that would make the joist system 2x6 8" OC.

I want to know which one would be better to try.

How can I find out since there are no calculators I can find online that will allow me to get the appropriate spans as a function of sistered 4x6 joists or at a spacing of 8" OC?

The thing is the former owner added a second story, but did not reinforce the 2x6 ceiling (floor for the 2nd floor) joists. He simply laid 2x4's perpendicular to the "ceiling" joists 16" OC and used a single layer of tounge and grooved 3/4" floor boards. Upon inspection there are many places where the crossing 2x4 do not even tough the underlying joists.

The rest of information: Southern Pine grade #2; dead and live load of 10 and 40, respectively; deflection of L/360.

Maybe you could help me with an exact answer or tell me where should I look to calculate myself.

Thanks in advance!

I think the previous owner did a lot of work with out a permit. The old ceiling was allowed to be 2x6 rafters but that isn't what is needed for a second floor floor joist, should be 2x10 but tell us how long are the joists too. When you doubled the 2x6 you have reached an acceptable load for most situations. The next corner he cut was skipping a sub floor under that pine floor. If you really want to do this correctly you need to pull out those 2x4 runners and install a 1/2 to 3/4" sub floor of plywood or particle board flooring glued and screwed. How much does the pool table weigh?

How much does the pool table weigh?[/QUOTE]


1000 lbs

Got yourself a real slate table then. How about the length of the joits between load bearing supports? Curious, since this is 2nd floor how are you getting in to sister joists?

Kyra, you really need to post a lot more info, span lenghths, are the spans continuous? Does the pool room extend across the entire span? You might consider using engineered lumber, use the TrusJoist calculations and ignore the 2x6's except as an existing way of holding your ceiling up. BTW, sistering on wood doesn't change the OC mesurement.

Forgot this link in the last, it's for the TrusJoist calculations;
Search

Terry, I am sure that link could be helpful but not the way it opens, can you refine it down to the correct page regarding calculations? My next concern after getting the joists correct is how best to handle a 250 Lbs/ sq. in. under the four table legs and avoid floor deflection. You mat need two layers of 3/4 flooring glued and screwed.

I'm sorry but I can't narrow it down anymore until I know more about your current span.
Btw, to calculate for dimensional lumber, try this:
Maximum Span Calculator for Joists & Rafters

You can also try this one...
Span Calculator

just adding a joist will not help, you'll need to run a drop girder underneath the joistrunning in the opposite direction, as for the size a treated 4x6 will work, and use metal support post for the support, 2 every 6 ft