z purlins

[l'ordinary bonville]

That's what most industrial sheds are made of

 

[Hesston4860s]

Can someone shed some light on making anti sag bars ?. My purlin centers are 1270mm I've been told the sag bars should be 1270 less the thickness of a purlin and a sleeve. To me this seams wrong and the sag bar should be 1270mm as when the purlins are fitted to the cleats the distance between the cleat faces will still be the same !.
Or am I missing some thing ?.

Just to add I'm not using push fit bars as there crap I'm using bolted back to back side rail bars.

 

[JNP]

The length should be the spacing - the thickness - 1 or 2 mm.

The spacing goes from back to back so you have to allow for the sag to go back to front, therefore - the thickness. Then with any cold rolled sags, roof or sides you should allow - 1mm each end just for tolerance. You should ignore the sleeve as that won't be anywhere near the anti-sag.

 

[Hesston4860s]

The length should be the spacing - the thickness - 1 or 2 mm.

The spacing goes from back to back so you have to allow for the sag to go back to front, therefore - the thickness. Then with any cold rolled sags, roof or sides you should allow - 1mm each end just for tolerance. You should ignore the sleeve as that won't be anywhere near the anti-sag.

Ahh yes makes sense now I think !.
So on 1270 centres with a 1.8 mm thick purlin I should have a sag bar of 1270 - 2.8mm = 1267.2 the 2.8mm being the purlin and 1mm tolerance.

 

[JNP]

Yeah, 1270 - 1.8 (2) - 2 = 1267mm overall