Universal column timber packer for joist hanger

[adampaulcrickmore]

Hi all, I have a 152x152x30 UC. Where the web meets the flange on top and bottom there is a root radius of about 1cm. I intend to place timber inside the steel web so that I can nail joist hangers to the face.
I relatively simple question but is it more common to round off the edges of the timber so it fits snug into the steel or just place a strip of 1cm thick wood into the web first to overcome the curved root between the web and flange and then timber on top.

Diagram to follow

Thanks

 

[adampaulcrickmore]

 

[Deleted member 174758]

Knock the corners off with a rip saw or a power plane and try to ensure that your timbers are a good tight fit if you must do it this way. Personally I can't see what's wrong with landing the joist end directly in the web and notching out to get it to fit - that is pretty much standard practice - or does it mean cutting out too much of the strength? If you do go for the infills the UB and timbers will need to be bored and the three layers of the "sandwich" bolted together using coach bolts and large washers

 

[adampaulcrickmore]

Thanks for the reply. Didnt mention in the OP that it is for a loft conversion and that I need to use joist hangers to keep the joists as low as possible for head space. As an aside is there any issues with forward and aft movment of the joists, if they were hung completely below the steel as per the picture below. Would noggins be sufficient to prevent movement?
Thanks

 

[Deleted member 174758]

As an aside is there any issues with forward and aft movment of the joists, if they were hung completely below the steel as per the picture below. Would noggins be sufficient to prevent movement?

Solid strutting in joists (not really noggins as there are sort of rules about size, position, etc) will certainly make the floor less bouncy, but if your sub-flooring is a man made board screwed and glued onto the joists you'll probably experience very little, if any movement. The mass and weight of the whole floor which forms a single entity (if glued and screwed) will see to that. Incidentally the accepted size for solid strutting is the same width (and ideally same depth) as the joists but in any case at last 70% of the depth of the joists (so for 225 x 50mm joists the minimum size solid studding would be 158 x 50mm). Solid strutting is always set at 1/3 and 2/3 the width of the space

 

[adampaulcrickmore]

Thanks, appreciate the help.

 

[^woody^]

You tend to find that timber is not conveniently the same thickness as beam flanges

Hangers are not designed to hang below the thing they are hanging off. In that photo, there is a lot of shear force on the hanger at a single point just above the joist which the hanger may not be designed to deal with. Normally, every nail or screw in the hanger transfers a bit of load, in that photo they don't. Struting or noggins have nothing to do with that, and that floor will move and create potential stress on the hanger by virtue of that.

 

[matlob]

I'm in the same situation where i need the floor to hang as low as possible.

I've come across the below which seems to suggest the joists can sit below the beam. "Tmax height can be greater than joist height"

I'm just working out the lowest I can go to determine if the project is viable.

 

[Deleted member 174758]

You tend to find that timber is not conveniently the same thickness as beam flanges

Which is why timber yards will rip to exact size, surely?

Hangers are not designed to hang below the thing they are hanging off. In that photo, there is a lot of shear force on the hanger at a single point just above the joist which the hanger may not be designed to deal with. Normally, every nail or screw in the hanger transfers a bit of load, in that photo they don't.

Agreed that every available hole should be filled with a twist nail (never screws which have a much lower shear loading, often exhibit poorer pull-out resistance and in the main won't meet the approval of an S-E or the BCO), but there are joist hangers specifically designed for these situations as shown in the Simpson Strongtie technical material. I've installed floors in this manner several times on large jobs where the approach was mandated by the S-E, so whilst unusual it isn't unknown

Struting or noggins have nothing to do with that, and that floor will move and create potential stress on the hanger by virtue of that.

Strutting will prevent bounciness, but if the joist calculations have been done correctly then surely that won't be an issue

 

[^woody^]

Strutting will prevent bounciness

Stiffen the floor yes, but not prevent the slight sideways sway that would occur in the situation shown in the OP.

 

[Deleted member 174758]

But if the flooring is a T&G sheet material glued and screwed or glued and nailed onto the joists (as it should be) and they have been solid strutted you will end up with what acts almost as a sort of one-sided torsion box. And in that case the struts will not only impart stiffness to the sub-floor support, but they also limit any tendency for the joists to turn under uneven loading