1st floor - floor joist crack

[Craabonn]

Hi All!

Doing some renovation and my brain just noticed this a joist crack, see images. Joist dimensions are 165 mm x 74 mm.

As far as I can tell, the crack runs the length of the joist within the room (3.45 m), on botch sides of the notch. Becoming more hairline after about a metre from the notch. There is a degree of twist of the joist above the crack at the notch area.

This notch cut is 55 x 108 mm. From my maths, if the rule of thumb is notch depth 0.15 x joist depth = 0.15 x 160 mm = 24.75, my notch is.. deep! My superficial understanding of the notches, they are a whole ball game in themselves. Open to your responses

 

[yorksbuilder]

Look up 'sistering a joist' and do that with glue, screws and plywood, or more softwood, should stop any more movement

 

[^woody^]

You probably need to glue and screw a ply plate to cover the joist both sides around all those notches, and a longer piece of ply to cover that split on the joist.

 

[Craabonn]

It is what I expected!

Is it worth herringbone or blocking at the significant cracking point, against the twist. Then sistering the other side?

 

[Harry Bloomfield]

Might there be some value in closing that crack up? A long drill bit, drill straight down vertically, through the joist, and out the bottom. Countersink the holes, top and bottom, for nuts and washers, plus 10mm threaded rod. Squirt some strong timber glue in the gap, and tighten it all up.

 

[Craabonn]

Might there be some value in closing that crack up? A long drill bit, drill straight down vertically, through the joist, and out the bottom. Countersink the holes, top and bottom, for nuts and washers, plus 10mm threaded rod. Squirt some strong timber glue in the gap, and tighten it all up.

Something like this maybe (below)? notch top, metal plate and bolt down? as found in a different thread. Either bridging the notched area or just over the cracked area, or span the notch and a length over the the length of substantial cracking?

 

[Harry Bloomfield]

Something like this maybe (below)? notch top, metal plate and bolt down? as found in a different thread. Either bridging the notched area or just over the cracked area, or span the notch and a length over the the length of substantial cracking?

Even better!

 

[^woody^]

Something like this maybe (below)? notch top, metal plate and bolt down? as found in a different thread. Either bridging the notched area or just over the cracked area, or span the notch and a length over the the length of substantial cracking?
View attachment 399870

No. Support really needs to be on the sides.

You can't put angle iron on top of a floor joist like that anyway!

 

[Craabonn]

So out of mental complexity.

I am blocking the joist against the twist, then sister the other side. As I am here, I will then block all the joists and plywood all notches that need it.