fitting joists to RSJ, is there a hanger

[browfish]

I need to fit some joists that will be supported on a wall at one end but on an RSJ at the other. The bottom of the steel is about 100mm higher than the wall so the joist can sit on top of the steel and if it is nottched into the web then only the top 100mm of the joist will be supported. Is there a joist hanger that can be fitted to RSJ's and how do they fit.
Any help appreciated. Thanks

 

[noseall]

Bolt a timber into the web then use jiffy hangers.

 

[^woody^]

. The bottom of the steel is about 100mm higher than the wall so the joist can sit on top of the steel and if it is nottched into the web then only the top 100mm of the joist will be supported.

That does not make any sense

Are the joists sitting on top, in, or lower than the steel?

If you notch joists at the bearing, then you are reducing the effective section size

 

[noseall]

Sounds to me as though the joists will be hitting the steel mid-depth, i.e. the joists will be lower than the steel by 100mm or so.

You can position a (long leg) jiffy so that it hangs down below the steel and still fix the jiffy to a timber bolted into the web.

 

[joe-90]

Did you make that drawing, Nosey? If so - how?

 

[noseall]

Nah, chopped it off the 'net.

I have used Sketch-up with some degree of success and have produced similar drawings. Sketch-up allows you to copy things like steel beams, stairs, timber elements. etc and use them in your drawings. You are able to rotate the drawings so that you can position them anywhere in a three dimensional plane.

You can push, pull, rotate, elongate etc so it is good stuff.

 

[joe-90]

I've got sketch-up but I can't seem to get it to do much so far. I guess I need to work on it.

 

[browfish]

You are right, the joists hang lower than the steel and the top o ge joists is half way up he web. Hat sketch would work but I can't fit a timber on the top or get to the other side of the steel. Will notchin out the beam be detrimental as from memory from my engineering days e maximum bending moment will be at the middle of the span
Thanks

 

[^woody^]

maximum bending moment will be at the middle of the span
Thanks

Yes, but in shear at the bearing, the timber will only be as good as timber of the reduced section depth - eg 100mm depth

You need to put the timber in the web as per noses' image and make sure it is tight. Then some hilti nails will help.

Then face fix some hangers

 

[browfish]

OBviously alot of joists are notched to level them up. Are there any rules on how much of a beam can be notched out? If 20mm is ok is 30? 40?, 50? where do you draw the line?

 

[^woody^]

Obviously?

Or are joists packed up instead?

I would draw the line were the notch reduces the section depth to such that the joist is no longer adequate. So if say, you need 200mm deep joists, then you don't notch them to make them less than 200mm

 

[noseall]

There are many similar buildings with differing load scenarios and that in some circumstance a cut (reduced) joist would not make a difference in one, whereas in another it could be catastrophic.

It is true to say that one cut joist amongs others that are whole will be supported by its mates and the floor boarding above

However, severely chopping a whole series of joists at the same point would be suicidal and stupid.

 

[saz84]

Bolt a timber into the web then use jiffy hangers.

How far apart do the bolt centres need to be when bolting timber into the web? There are 2 rsj's 3.5m and 4.5m long.

 

[RonnyRaygun]

Bolt a timber into the web then use jiffy hangers.

How far apart do the bolt centres need to be when bolting timber into the web? There are 2 rsj's 3.5m and 4.5m long.

600mm staggered.

 

[tony1851]

Shear at the ends of domestic floor joists is rarely a problem. If, say, OPs joists were 200 deep, would be Ok to cut 50-60 from the bottom.