Hello, and a 20x30 floor joist question

[vanbavel]

I just started preparing to build the 20 x 30 1.5 story on a remote location in Alaska.  I plan to modify the foundation by adding a central beam and reducing 1st floor joists to 2x8s, 16" o.c.  How much overlap is necessary at the center for stability?  Is it better to run a 2x8 down the center atop the beam and hang joist on either side?  Can I use butt joints and Simpson ties at the center?  Thanks for the forum!

[MountainDon]

   vanbavel

The IRC2006 section R502.6.1 states that "Joists framing from opposite sides over a bearing support shall lap a minimum of 3 inches and shall be nailed together with a minimum of three 10D face nails."

Section R502.6.1 goes on to state, "A wood or metal splice with strength equal to or greater than that provided by the nailed lap is permitted."  But the IRC does not elaborate on what devices might meet that criteria.  

My personal choice would be to have the joists on top of the supporting beams rather than hang them using metal hangers. For one thing it's a lot easier to place the butt end of the joist against the outer rim position and let the center overlap fall where it may. Having to cut each joist to length to fit in the hanger is more work. You should use solid same size blocking between the joists where they overlap over the joist.


You can access the VA version of the IRC2006 from our Referral Links section. Look for the topic Building codebooks online in the upper 'sticky' section. There are state to state variations, but most of the info is general.

The AK code does not seem to be available online.

We'll all be looking forward to seeing pictures as you progress.  

[vanbavel]

Thanks for the quick reply!  I think I will take your advice and lap at the center, as I am all for fewer measure/cut opportunities.  I will be taking pictures as I go.  It will be a couple more months or so before the ground thaws enough to place the 6x6s.