Lumber span rating?

[deputydawg]

In my addition project I am adding a bathroom to what is now my attic space. It will be approximately 10 x 9. <br />I can't find my chart for lumber span rating...what should I use. The span will run the 10 foot length, no supporting walls underneath except of course on each end of the run. I will be using select lumber, pine or whatever is cheapest from Menards.<br /><br />There will not be a bath tub, just a toilet, sink and stand up corner shower. <br /><br />With that span, using 3/4" sturdifloor, what should I use for the floor joists? I am thinking 2x8 would be strong enough but can't find my charts to know for sure.<br /><br />Right now the ceiling joists are just 2x4. I know that is not close to heavy enough for the weight.

 

[Pony]

Re: Lumber span rating?

Im trying to remember some of my structures work from architecture last year. Hopefully someone will come by and either verify mine or give you the correct answer. (either way this bumps u back to the top)<br /><br />Here what I remember:<br /><br />For a span of 10ft, I would think you would want a 4x10 piece of lumber laid on edge (If you are using a beam with joists on top)<br /><br />IF you arent using a beam, but are just using joists for support I would think a min of 2x8 at 12 inches on center; or 2x10 at 24 inches on center.

 

[18rabbit]

Re: Lumber span rating?

Presuming we are talking about 4-in thick walls, I belive the rule of thumb is 1-inch of lumber for each 1-ft of span. A 10-ft span wants a 10x4 header beam, minimum.

 

[vipzach]

Re: Lumber span rating?

deputydawg, take a look at this link, it has alot of good info for understanding spans and there are links in it that take you to some span tables. Good Luck!<br /><br /> http://www.awc.org/technical/spantables/tutorial.htm

 

[NoWorries]

Re: Lumber span rating?

When dealing with floors, you should go with 2x10-16"OC on that 10' span. A 2x8 is just not enough to support much, and you will probably notice a slight spring to it when walking. Also, with this being a bath, the plumbing from the shower will be in the floor joist cavity. It's easier to plumb inside a 2x10 than a 2x4! If the addition is off an existing room, use what the other room used to make the floor level, if it's at least a 2x10.

 

[toomanyboats]

Re: Lumber span rating?

As a General Contractor for 25 years,I design and build homes in the toughest state,California.<br />Heres my 2 cents;<br />Don't use 2x8 even at 12" oc<br />The 1 inch per foot is a common rule but not always true.<br />2x10 floor joist @ 16"oc will still deflect some and be noticable when walking,and will get worse if you decide to put tile on it.<br />I never use any thing less than 2x12 @16"oc/or 11 1/8 Truss joist @ 16"oc,A little over kill will never hurt ,But a mistake will haunt you!<br />Take this from someone thats been there,hundreds of times.If you need to know anything else let me know.

 

[deputydawg]

Re: Lumber span rating?

Thanks for the info. I think 2x12 at 12"oc is what I will use. That way if I ever get rich enough I can put in the small hot tub I have been wanting. <br /><br />To clarify what I am doing, I am not changing the room I now have downstairs. I am finishing a room in the attic. The span will run from an exterior wall on the north side of the existing house, to an interior wall in the center of the house. Each end of the floor joist will rest on the top sill of a 2x4 wall on each end. Right now the ceiling joists above the existing house are 2x4, running the same direction (north to south) as the new ones I am adding. I will be running the new thicker floor joists in between the 2x4's. The reason for this is right now in the lower existing house I have antique decorative tin ceilings. I don't want to have to take these down to replace the 2x4's with 2x12's. <br /><br />Thanks again for all the info everyone.

 

[Ron G]

Re: Lumber span rating?

I like the idea of the trusses if the money is the same as 2x12's,i put the trusses all through moms house when i built it with advantec flooring,talking about strong.