Previous Thread
Next Thread
Print Thread
Rate Thread
minimum drop in joist pocket size #35766 04/12/20 05:18 PM
Joined: Jul 2007
Posts: 13
5
51steve Offline OP
Member
OP Offline
Member
5
Joined: Jul 2007
Posts: 13
Hello Everyone,

I am in the design stage of installing 10 foot long 5x7 white oak drop-in floor joists on a preexisting 11 foot long 10x11 white oak summer beam and I was wondering if there was a minimum drop in joist pocket depth? Looking at the "floor joist sizing rule of thumb" the depth should be less than or equal to 5/8ths of the width of the beam. Based on the spacing of the joists(31 inches on center) and the load each pocket will need to bear 715 lbs. I would prefer to make the smallest pocket possible because 1) I dont want to weaken the summer beam. 2) It's oak that's been drying for 10 years! I will be scoop cutting the floor joists down to 5 1/4 so my pocket dimensions will be 5 x 5-1/4 x depth... that's what I need help on! There will be 5 3/4 of wood underneath the joist pocket.

Thanks in advance!

Steve

Re: minimum drop in joist pocket size [Re: 51steve] #35767 04/12/20 09:11 PM
Joined: Nov 2008
Posts: 568
Jay White Cloud Offline
Member
Offline
Member
Joined: Nov 2008
Posts: 568
Hello Steve,

There is, as you suggested many old "rules of thumb" for such applicaiton. Another is "2 and 3...3 and 4" which translates into the distance in inches between joist pockets on the top of a Summer beam and the distance from of the pocket on the bottom...min and max.

I'm found of soffit and/or tusk tenon for such applications, not dovetails...even if the tenon has to be "free" and slid in.

Your timber sizes seem more than adequate if I'm understanding the overall design without seeing a CAD or drawing, so no issue there.

Your reduction of the joist (aka scoop cutting) seems acceptable but not necessary at all, and would only be dependant on aesthetic you are trying to achieve. A fully house joist appears achievable if it is desirable...

As to the "smallest pocket possible" that motivation for strength maintenance is not really a concern it would seem? As to cutting the pocket, a "v" gouge (aka corner chisel) and a #5 in or out cannel gouge would make short work of this task in either green or dry oak without much effort. Then simple cleanup with slick or paring chisels...Of course any applied power tools and/or saws can be employed according to skill set, tooling and applied knowledge to effectively use them of course is also part of the tooling should you have these?

Hope that was of some use...

Regards,
j


Last edited by Jay White Cloud; 04/12/20 09:16 PM.
Re: minimum drop in joist pocket size [Re: 51steve] #35768 04/13/20 01:03 PM
Joined: Oct 2002
Posts: 207
Will B Offline
Member
Offline
Member
Joined: Oct 2002
Posts: 207
1"

Re: minimum drop in joist pocket size [Re: 51steve] #35769 04/14/20 12:58 PM
Joined: Jul 2007
Posts: 13
5
51steve Offline OP
Member
OP Offline
Member
5
Joined: Jul 2007
Posts: 13
Thanks for the quick replies and helping me through this process! I have been scoop cutting a few trial joists on scrap pieces with fair results and hope to cut some sample pockets soon before heading on to the "real thing".

Thanks again!

Steve


Moderated by  Jim Rogers, mdfinc, Paul Freeman 

Newest Members
Francis, Alexl97, Holmstrom, ShaneMcGovern, Trenton328
4980 Registered Users
Powered by UBB.threads™ PHP Forum Software 7.7.3
(Release build 20190728)
PHP: 5.4.45 Page Time: 0.024s Queries: 15 (0.006s) Memory: 3.1305 MB (Peak: 3.5826 MB) Data Comp: Off Server Time: 2020-09-29 03:08:32 UTC
Valid HTML 5 and Valid CSS