Marking out joist hangers . Not as easy as I thought

[ProDave]

Here is another question you may not have thought about.

 

Strongbacks.

 

Generally any posi joist system over 4M span will have a strong back threaded through all the joists, think of it as the posi joist equivalent of noggins.

 

How do you slot it in?

 

With our timber frame, it was slotted in before the ring beam was installed. But you have solid walls.  So you are probably going to temporarily have to stack all the joists tight together at one side of the building, slot the strongbacks in, then spread the joists out.

 

Sorry to give you one more issue to address.

[Mr Punter]

Also if you have rigid ducts or pipes you may need to put these in as you go.

[Russell griffiths]

Just a thought

should you not put this job on hold until you 100% sort out the joist cock up

if for any reason you end up planting a plywood stiffener on to your short joists you may need to use a wider hanger to take the wider joist

i would sort out one problem before you have to redo stuff. 

[ToughButterCup]

  On 28/11/2018 at 16:01, ProDave said:

Here is another question you may not have thought about.

 

Strongbacks.

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No need. I'm grateful for small Murphies at the moment 

[ToughButterCup]

  On 28/11/2018 at 16:26, Russell griffiths said:

Just a thought.... 

i would sort out one problem before you have to redo stuff. 

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See above.... Oim an appier man than I wuz yesdee 

[Simplysimon]

start in the middle of the wall, set a joist on top of the wall plates, square this one to the wall plate and work outwards towards the ends.

oh, bu&&er, that wont work.

[Onoff]

Are the opposite walls parallel?

 

Seem to remember I had a similar situation in the bathroom which was basically an irregular quadrilateral.

 

I just had to accept that the majority of the joists would be 400mm centres but the last one would run in <400 and not be quite parallel to the adjacent one.

 

 

[mvincentd]

I countersunk wherever I encountered the clash.

If you just faff a bit to get your first joist (or set of hangers) parallel to the wall it runs alongside then just cut a 400mm spacer to hold against the fixed hanger(joist) and mark for the next one.....your ostensibly oblong room is going to have to be very 'jelly'  to throw the joists significantly off parallel.

Give consideration to your decking sheet size and plasterboard sheet size...your first joist is likely 50mm off the parallel wall face, you might not want your 2nd joist at 400 centre because continuing that way will put the 4th joist centre at 1200+50+(0.5xJoistwidth) yet you're only going to set your plasterboard maybe 10mm off the parallel wall face.

Defo strong backs and mvhr ducting slid in as you go.

 

[ToughButterCup]

  On 28/11/2018 at 23:05, mvincentd said:

I countersunk wherever I encountered the clash.

If you just faff a bit to get your first joist (or set of hangers) parallel to the wall it runs alongside then just cut a 400mm spacer to hold against the fixed hanger(joist) and mark for the next one.....your ostensibly oblong room is going to have to be very 'jelly'  to throw the joists significantly off parallel.

Give consideration to your decking sheet size and plasterboard sheet size...your first joist is likely 50mm off the parallel wall face, you might not want your 2nd joist at 400 centre because continuing that way will put the 4th joist centre at 1200+50+(0.5xJoistwidth) yet you're only going to set your plasterboard maybe 10mm off the parallel wall face.

Defo strong backs and mvhr ducting slid in as you go.

 

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This is a bloody steeeeep learning curve.

[ProDave]

Also think about what might go UP between them, WBS flue? Stack pipe? etc. That will create "avoid" zones just to make things a bit more interesting,