- Location
- Near Colchester
I have seen many livestock buildings with 20 foot bays and wooden 9 by 3's look very saggy,
Any thoughts, steel are more money atm.
Any thoughts, steel are more money atm.
Wooden or steel purlins?
- Thread starter Pan mixer
- Start date
- Location
- East Sussex
Z purlins will rot, got a couple of straw barns here that will need re roofing due to corroded purlins probably due to the fact they have had livestock them when we are well stocked. Go for wood.
RWG Contracts
Member
- Location
- Samlesbury, Lancashire
Wooden purlins on livestock buildings. Weld 2' cleats to the steel, will reduce the span to 18'
multi power
Member
- Location
- pembrokeshire
Maybe worth a mention, there is a couple of sheds here where end bay is bigger, bigger purlins in them bays and they have not sagged but the 15 ft bays have.
Forever Fendt
Member
- Location
- Derbyshire
if you can get them you want imported timber from Baltic states it is a lot slower grown and the growth rings are more even it beats home grown hands down when it comes to 20 ft bays ,we did a 300 ft long slatted cattle shed not far from the Solway coast about 15 years ago and the zeds have been replaced last summerI've one the same,15' purlins put up when wet and they sagged a good 3".
Exfarmer
Member
- Location
- Bury St Edmunds
Be aware that pressure treatment is not what it was, in fact it is probably not worth doing.
- Location
- Near Colchester
Nor is galvanizing though
- Location
- East Yorkshire
There's certainly a world of difference between hot-dip and electro-plating, but I would of thought that hd galv is the same as its always been. Electro-plating, as in z-purlins, is just one step up from paint and is no substitute for hd.
As for wood; yes the quality is generally poor, and I would agree it is best dried before installation. The moisture can add significantly to the weight leading to sag.
Forever Fendt
Member
- Location
- Derbyshire
mos
t zed pulling are 1.4mm thick and some 1.6 we use 2mm they are a lot sturdier and should last longer if the shed is plenty high enough it will increase the lifespan of the zeds
Or put purlins in which overlap. 22ft purlin in 20ft bay makes the purlins effectively 18ft long (as long as you bold them together!)
Forever Fendt
Member
- Location
- Derbyshire
you will need longer sheets then if you using big 6
MD @Minshall Buildings
Member
- Location
- Shropshire
For reference Z purlins are not electro plated but are made from galvanized sheet that is then cropped and folded into a Z shape. The coating is better than electro plating but certainly not as good or as thick zinc coating as you would get if you used un coated steel that was then galvanized after folding. Problem is not many would pay the extra cost!
Possible solution could be to overpaint the purlins prior to erection. Bit time consuming and more cost but cheaper in the long run than early replacement I suspect!....
- Location
- Near Colchester
Be a bit tricky to get paint to stick to new galv though?
MD @Minshall Buildings
Member
- Location
- Shropshire
It's not so much of a problem these days , just paint galv with "T" wash first and then overpaint. Or some paints actually come with a etching solution built in so key to galv quite well. Much easier to do all this before installation if you want to extend life of steel purlins.
- Location
- East Yorkshire
I'm sure people would pay for a better, more resilient factory finish, rather than have to start painting them from new........I certainly would.
Aren't modern spouting bolts electro plated? They're hopeless in comparison with the old hot dipped ones: I just assumed the z purlins were the same. Whatever, the finish on z's is not fit for purpose in my view.
Forever Fendt
Member
- Location
- Derbyshire
zeds last well in the environment they were intended for in industrial buildings, but due to there use in cattle buildings there life span is reduced and can be as little as 10/12 years if you are able to source imported graded 9x3 from the baltic states this would be my choice on buildings of 15 deg or less , well designed and ventilated buildings should have less problems with corrosion and the use of stainless steel screws will help
MD @Minshall Buildings
Member
- Location
- Shropshire
yes you are correct about bolts the vast majority are now zinc plated which is a much inferior protection vs. HDG. I suspect as the vast majority of steel purlins go into industrial buildings where corrosion is not an issue that is why the have stayed with the pre galvanized material they use. sadly, I suspect you are in the minority about paying for better as we see every day how price seems to be the driver over quality for most buyers for agricultural buildings in general !