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jmac1, carpentry, electrical, plumbing
Category: Home Improvement
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Experience:  Professional Home Improvement Contractor 15 years
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how do join together two wooden flooring joists

Customer Question

how do i join together two wooden floor joists, as one end of the joist into the wall as been removed
Submitted: 9 years ago.
Category: Home Improvement
Expert:  jmac1 replied 9 years ago.
The process in which you join two structural floor joists together is called sistering. In order to do this you must clear out an area directly adjacent to the floor joist you are trying to repair, from the nearset load bearing header to the plate that the original joist used to sit on. Next, trot down to your nearest lumber yard and pick up a piece of lumber in the same size as the joist your are attempting to sister. Now, take a measure from outside of the plate(the spot where the old joist used to end) back to at least 3 1/2" over the nearest load bearing header or plate mentioned before. If you can extend 3 1/2" onto the load bearing member, that is good. If not, you should have at least 2" on minimum. Now for the hard part. The easiest way to sister a header in existing framing is to lay your new member on the flat in between the joists, next to the one being repaired, and attempt to work the new piece of lumber into the same position immediatly next to the joist being repaired. Easier said then done. One trick to ease the pain of this process is to break out your power planer or if your handy enough with a skill saw, and take a bit of the top corner of the joist your trying to stand up. Next, employing a few good clamps to help the process can work well. At any time during this process, a good sledge hammer for persuasion can be very helpful. Once your new joist is next to the old one you want to nail the two together with ten penny framing nails, unless, the load is extrodinary, in which case carriage bolts are better. THIS METHOD WORKS WELL IN A PERFECT WORLD. By that, I mean, a situation where you are able to sister the new joist next to the old from plate to header. Very often, this will not be the case. In this case, the general rule is for every two feet you need to make up for, you want to extend your sister joist back at least 8 feet if possible. If the load requires it and neither of these scenarios is going to work, you have now entered the wonderful world of steel flitch plates. These are a lesson for another day. Basically with the materials and tools needed for this job in front of you, it is a fairly straight forward and not to difficult repair. I hope this helps. If you fall into a situation other then the few that I have described to you here. feel free to mail me with the specifics and I will be more then happy to narrow down my anwser to your specific dilema. Good Luck.

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