What is the proper way to repair cracked & improper notched joists?
How long should the newly sistered repair be?

I recently inspected a home where numerous joist where improperly notched and the city wanted the seller to make the neccessary repairs.

I thought the sistering was marginal at best.

What are your thoughts?


The sistered joists should extend well beyond the notch or hole. Your photo shows that is not the case.

Improvement required. On the other hand the notches are not new, and likely the joists have not exhibited any signs of distress over the years.

Raymond Wand
Alton, ON

David, I usually go past the notch or hole 2’ from both sides of the area in question.

That being said I don’t know what code asks for if it does at all.Intuitively 2’ has always “felt” like enough.Also I use screws to fasten the repair together.

Now look what you’ve done.I can’t stop thinking about it and now have to go look it up.If I’m wrong I’ll get back with you.

I don’t know what the requirement is either but 2’ sounds ideal. Of course there is nothing stopping them from extending from beam to outer wall, except electrical wires possibly and other hinderances.

Raymond Wand
Alton, ON

Raymond Wand
Alton, ON

I would think at least 90 to 100 years like the rest of the house. :cool: :mrgreen: :cool:

i’ve always been told that you need at least 300% the highth of the joist on either side of the repair and a minimum of 5 stagerd fasteners (not sure of type) per side. but i could be wrong. sounded good to me though.

:slight_smile: :slight_smile: :wink:
Jay; You are stating facts that come from Engneers’, 300% should cover it.
*Why run calculations? That should do it. ha.ha. *
*Since you are allowed to notch a joist in the first third to D/6, and D/3 double that amount would loggically be adequate for a splice. Therefore, a four foot splice which is common to see in this type of repair, would be more that adequate. *
*Marcel *

It appears that the shim on the rear support column is not centered and is leaning.

Erol Kartal

That repair is not doing a thing…is the lumber yellow pine, oak…??? These need to extend over more than the middle three-fourths of the knotched member, unless the joist exhibit signs of distress at their ends (cracking, splitting). In this case, the sistered rafter(s) should extend over the full length and bear solidly at both ends.

that’s ‘cuz lots uf mi lernin’ came from books and such. seriosly, i read about 30 u.s navy manuel issued to Sea B’s and thats all they do is numbers. suprizingly some off it stuck to the cobwebs in my head.

I am of the “never too much” school of thought. I have a tendency to over bulid, which I must say has served me well in the past. I would have sistered as far as possible and damn the cost of the lumber. Better safe than sorry. I will even go so far as to sister up perfectly good floor joists if I get a complaint about spring in a floor from a home owner.

that makes sense Larry. i mean think about it, you’d have to cut a piece of lumber to a spacific length for it to be ‘‘code’’ so why not use the whole thing, or as much as you can. it’s not like the d.o.t. is going to bust ya for being over weight.

Larry I would be the first one to agree that sistering would envolve exactly that sistering the whole member from one end to the other. That is the ideal condition, but unfortunately, there are the in betweens and the half fast jobs that occurr and we have to inspect. People like to know what is adequate by code and bare neccessities required to do the fixes, and not what should be done.

I tell them what I think should be done as a professessional and note what I see. What they do afterwards is up to them. I have covered my butt, and it appears today, that is what you need to do with people out there that are completely illiterate to construction techniques and don’t care to know. They look at the pocket money and make indecisive conclusions.

Talk alot, say alot of things to educate the client, and write hard noting everthing at hand.

Marcel :slight_smile: :slight_smile: :wink:

I learned somewhere that the sistered-on section should extend 2’ on either side of the hole, notch or crack. If it is printed, where is it?? Anyone?

wouldn’t follow that rule.

Sistering can be done from underneath, and can stop just shy of both ends because they use the bearing of the original joist in it’s pocket. Alternatively there is no difference if you used angle iron to span the notch, the weight will still be picked up by the remaining joist. But if the floors are springy to begin with as it typical with an old/older home then I would be inclined to run the sisterd joist the full length of the joist, less the pocketing.

Raymond Wand
Alton, ON

okay, what rule would you follow?


What are you looking for? Some rule? I don’t have any rules because as far as I know there is no written rule (i.e. code on repair of joists) or specific rule. I guess it boils down to good engineering practices.

Have you done a search on Google or one of the other search engines?

Raymond Wand
Alton, ON

:slight_smile: :slight_smile:

**Hank; **
**I think what Raymond is trying to tell you, is that are no writen parameters on when a joist needs to be sistered, unless the obvious tells you to do so by experience and/or a structural Engineer in some cases if the component is structural. **

**Residential sistering can be accomplished in different ways, reference to the IRC on notching and boring of joist might be of some help. **
**Extremities of these codes could help you decide whether or not sistering should be recommended. **

**Sistering defined;= the reiforcement of a joist by nailing, or attaching alongside the existing joist, another joist or reinforcing member. **

**Hope this helps. **

**Marcel **