Originally Posted by
silentC
Here's an example:
A number of times over the last couple of years, I have seen the question asked "should I nail or screw my timber decking to my Duragal steel joists". The gut reaction of most 'experienced' people, is to say "screwing is better". This is the accepted wisdom.
However, if you look in the installation manual for Duragal, it says clearly "OneSteel does not recommend screwing timber decking to Duragal steel joists". It's not excluded by omission, it specifically states that it is not recommended. Now how many blokes do you reckon have screwed their deck down, either not knowing any better, or thinking that they do? Why has OneSteel gone to the trouble of pointing it out?
I bet I know why. I bet in the early days of the product, they had some warranty problems and the boffins determined that the cause was the screws. So to avoid future warranty issues, they print on all their material that screwing is not recommended. If Bob the Builder goes ahead and screws it anyway, he is screwed when it comes time to make a warranty claim.
I don't know why screwing instead of nailing causes a problem. Try and find anyone who works for OneSteel who knows. In fact I've heard at least one story of a OneSteel employee telling someone to ignore it.
Don't you think there is a reason though? Why would they limit their application that way if there wasn't a good reason? Yet so many tradies feel that it can be ignored, or are completely ignorant of the recommendation. Because they know better than the boffins at OneSteel. If they proceed to get their screwgun out regardless, then as far as I'm concerned that is cowboy behaviour. If I felt strongly enough that it was worng, I would ring OneSteel and keep trying until I found someone who could explain to me why. Then I would decide if it was warranted or not on the basis of the information they provide, rather than just saying "well, it makes no sense to me, so I'll just ignore it".