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-   -   Floor Joist Notch Repair (http://www.diychatroom.com/f19/floor-joist-notch-repair-159509/)

harrydunn 10-09-2012 08:53 AM

Floor Joist Notch Repair
 
Greetings! First post.

We just moved into a new-to-us house built in 1980 with an upper and lower garage. Lower garage has a low ceiling and PO notched three floor joists closest to the garage door so the garage door opener center rail would clear.

The notches are roughly 1.5" tall x 3" wide on average. 2x10 joists, 16" o.c., 11' span.

The house is very solid and there is no sagging but I'd like to repair it for peace of mind. Dining room above with small table and chairs. I've read about sistering the joists which seems to be the fix.

Question #1
Do I remove the garage door opener and sister with 2x10s or can I leave the opener as-is and sister with 2x8's to clear the notches and keep the garage door opener funtional? I definitely would like a garage door opener on this door somehow.

Question #2
If sistering with 2x10s is the answer (which means no garage door opener), I would not be able to run the sister joists the full span as there are a few holes drilled in the original joists for wiring. I could put a 2x10 up that would run about 3.5' to either side of the notches before I run into the wiring holes. Is this acceptable? I could run 2x8s considerable further to each side of the notch as they would clear the wiring holes, but just barely.

Question #3
Do I just use lag bolts to sister the new joist to the old? I'm not completely sure of the proper method.

Hopefully, this can be fixed relative easily and my house won't fall down. :)

Thanks!

As I typed this I found some quick-turn brackets that may work if sistering with 2x10s is the answer. They keep the top door panel lower as it runs vertically up the first section of track.
http://www.amazon.com/gp/customer-me...ery/B0052UCI0I

http://i1065.photobucket.com/albums/...n/photo1-1.jpg

hand drive 10-09-2012 09:00 AM

unless you go wall to wall with a new joist, any splice will not really help strengthen the joist. A new joist sitting on the outer walls nailed/screwed to the current joist will add strength to the notched joist. Even a 2x10 sistered with the same notch would add strength...

patented 10-09-2012 09:14 AM

Your house isnt going to fall down. That garage door has probably been there for years, with no issues.

Obviously, the best thing to do would be to sister new 2x10s onto the notched ones, but that means you would lose your garage door opener. Personally, that would not be an acceptable solution to me.

One option would be to sister on 3/4" plywood to each side (or 2 peices on one side) of the joist. You could cut the plywood to be the height of the notched joist, and glue and nail the ply to the old joist. This is what I would do.

If you are really concerned, call in a structural engineer. He will be able to tell you with certainty what the "best" fix is.

harrydunn 10-09-2012 09:28 AM

Quote:

Originally Posted by patented (Post 1027231)
One option would be to sister on 3/4" plywood to each side (or 2 peices on one side) of the joist. You could cut the plywood to be the height of the notched joist, and glue and nail the ply to the old joist. This is what I would do.

Thanks for the responses.

Plywood the full length of span? Not sure I can get it up in there, full span.

So, glue and nails with plywood would be better than lag bolts and 2x8s? The only reason I ask is that I have plenty of 2x8s laying around.

Thanks.

GBrackins 10-09-2012 09:56 AM

Quote:

Originally Posted by harrydunn (Post 1027221)
with an upper and lower garage.

I take it there is not a garage over this garage .....

harrydunn 10-09-2012 10:05 AM

Nope. Small dining room. The upper garage is on other end of the house.

mae-ling 10-09-2012 10:14 AM

2x8 spruce #2 or better will span about 12', your under that at 11'
Your notches turn your 2x10 into a 2x8 basically. As long as there is no cracking you should be good.
If you cut strips of plywood the 9.25" (depth of your 2x10) and 8' long. Cut the notch in it to clear the opener rail. Use adhesibe and screws or ring shank nails. Basically a gusset on each side. This will help stop any future cracking.

patented 10-09-2012 12:52 PM

Quote:

Originally Posted by harrydunn (Post 1027238)
Thanks for the responses.

Plywood the full length of span? Not sure I can get it up in there, full span.

So, glue and nails with plywood would be better than lag bolts and 2x8s? The only reason I ask is that I have plenty of 2x8s laying around.

Thanks.

Doesnt have to be full length, but longer is better. Rule of thumb is at least about 1/3 the length of the joist. The plywood will allow you to get a taller sister in there, which should add more strength than the 2x8. I am sure the 2x8s would likely be fine though. Personally, Id go the plywood route because it is much easier to manage and *might* add a bit of extra strength.

You should apply the plywood so that the seams are staggered.

tony.g 10-09-2012 01:58 PM

Assuming the notch is somwhere near the centre of the span, Mae-ling is correct in that it is effectively a 2x8. But if it's only an 11ft span, that should be OK in practice, even if it doesn't conform to your Code.

If you decide to sister the joists with timber or ply, you do NOT have to make the sisters the full span, so long as they are firmly nailed or screwed to the existing joists. A 6 or 7-foot length centred on the notch would be fine. This is because the bending stress in the timber is greatest in the middle and tails off to zero at each end.

If you really want to sister them, make life easy for yourself and use some of the 2x8s you have, but don't bother going wall-to-wall with them.

harrydunn 10-09-2012 03:13 PM

I appreciate all of the responses. I've got several 8' 2x8s that I believe I will bolt and screw to the old joist. I'm assuming there is no need for glue if I'm bolting together. I have a bunch of 1/2" bolts that I'll use with washers on each side of the joist.

Thanks.

tony.g 10-09-2012 03:41 PM

8ft lengths centred on the notches will be more than adequate on that span.
No need for glue if well-bolted; ensure bolts are staggered.

hand drive 10-09-2012 03:51 PM

while you are going through the whole process jacking up the joists to straighten them help, if they need it.

Daniel Holzman 10-09-2012 06:05 PM

Tony.g is correct in his comments. I do NOT recommend that you attempt to jack the existing joist level, given that there is a notch in it, you increase the probability of cracking the joist. Here is an alternative approach you may want to consider.

Acceptable settlement of a joist is measured as L/D, where L is the span length, and D is the deflection (use the same units for L and D). Typically for structural framing, an L/D greater than 240 is fine, unless you are installing tile or stone for supported flooring, in which case you need a stiffer floor. Measure the deflection at the center of the joist carefully using either a string line (easiest), a laser level if you have one, or a builders level. If the L/D is 240 or greater, have another beer and stop worrying. If L/D is less than 240, you may want to consider one of the sistering options previously discussed.

By the way, deflection usually controls in residential construction, so if the joist meets deflection criteria, it likely meets strength criteria as well. Without knowing the specific species and grade of lumber, it is impossible to determine the structural strength of the joist, but the deflection test is a pretty good alternative to full blown structural analysis.

harrydunn 10-10-2012 08:54 AM

Got the sisters up. I'm done worrying about it. If the floor ever starts to sag, I'll deal with it then. I'm not expecting to have to revist this issue, however.

Thanks for all of your input. You all were very helpful to a first poster on a great site.

:thumbsup:


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