Z purlins

snipe

Member
Location
west yorkshire
Just putting a second hand lean to up. On some of our new sheds the Z purlins fit in to a sleeve that sticks out about 2 foot each side of the rafter. Is that needed or can I put my z purlins straight onto the rafter(20ft span bays). Also the sag bars on a shed with an apex pull against each other, on a mono pitch lean to how do you stop the sag?
 

Pan mixer

Member
Mixed Farmer
Location
Near Colchester
Those sleeves strengthen the Zeds I think and should be used if they are on the spec sheet.

Tbh I have used some on sheds more recently - when they were designed with them and used to not use them but the zeds were heavier then.
 

Forever Fendt

Member
Location
Derbyshire
Just putting a second hand lean to up. On some of our new sheds the Z purlins fit in to a sleeve that sticks out about 2 foot each side of the rafter. Is that needed or can I put my z purlins straight onto the rafter(20ft span bays). Also the sag bars on a shed with an apex pull against each other, on a mono pitch lean to how do you stop the sag?
You need to use sleeves on the joints as it stiffens the zed and reinforces the holes and help stops them rolling, on a mono pitch you should use a diagonal tie wire at the eaves from the centre of the purlin back to the next cleat up slope on the rafter,there should be a bolted strutting this section not a push fit sag bar
 

AJR75

Member
Livestock Farmer
Location
Somerset
Some manufacturers will offer a free design service and spec up the purlin system for you. Well worth speaking to a few suppliers such as Metsec, Ayshire Albion sections etc
 

snipe

Member
Location
west yorkshire
Our shed builder wants to bolt the z purlins to the bottom/eves side of the bracket with the top of the purlin faceing the ridge, is this correct. Or would ithey be better sitting on the top side of the bracket so it not just the bolts supporting them but the whole bracket.
 
Hello @snipe, it is standard for the purlin to be on the bottom side of the cleat (picture attached). If it is fitted above the cleat the purlin would be facing the wrong way.
 

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Our shed builder wants to bolt the z purlins to the bottom/eves side of the bracket with the top of the purlin faceing the ridge, is this correct. Or would ithey be better sitting on the top side of the bracket so it not just the bolts supporting them but the whole bracket.

Your shed builder is correct


Maybe let him do his job, that’s why you’re paying him
 

snipe

Member
Location
west yorkshire
Out of interest why this way round. Would it not be stronger pushing back on to the brackets, thather than just the bolt heads. While I’m on here. I’ve ordered all the purlins the same length. Should I have got longer ones for the end bays so they go all the way to the outer edge or the gable end rafter, the one I have got will only go to the middle of it. Also we are using sleeves for the purlins to sit in on the middle bays, what do you do on the end rafters, can you buy half length sleeves
 
Out of interest why this way round. Would it not be stronger pushing back on to the brackets, thather than just the bolt heads. While I’m on here. I’ve ordered all the purlins the same length. Should I have got longer ones for the end bays so they go all the way to the outer edge or the gable end rafter, the one I have got will only go to the middle of it. Also we are using sleeves for the purlins to sit in on the middle bays, what do you do on the end rafters, can you buy half length sleeves

Bolt one on and try pulling it off, you’ll soon realise why the bolts hold.

Yeah normally order the end ones longer

Usually only put sleeves on the centre rafters
 

BobGreen

Member
Location
Lancs
Out of interest why this way round. Would it not be stronger pushing back on to the brackets, thather than just the bolt heads. While I’m on here. I’ve ordered all the purlins the same length. Should I have got longer ones for the end bays so they go all the way to the outer edge or the gable end rafter, the one I have got will only go to the middle of it. Also we are using sleeves for the purlins to sit in on the middle bays, what do you do on the end rafters, can you buy half length sleeves

The Z purlins on the end bays should be long enough to go to the outside of the rafters or actually the outside of the stanchions if rafters are narrower so the cleader angle can go on top
They should be punched with 4 holes to bolt directly onto rafters cleats and are left and right handed
 
Bugger. Can’t send purlins back. Any good ideas how to get round this. Would buying some sleeves and cutting overhang off work?
Slightly narrower end bays, it's what's been done on one of our older sheds with timber purlins, the end bays are a couple of inches shorter so that the timbers go through to the end.
 

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Red Tractor drops launch of green farming scheme amid anger from farmers

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As reported in Independent


quote: “Red Tractor has confirmed it is dropping plans to launch its green farming assurance standard in April“

read the TFF thread here: https://thefarmingforum.co.uk/index.php?threads/gfc-was-to-go-ahead-now-not-going-ahead.405234/
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