If you tighten up against a void, you'll crush and distort the metal and the fixing won't be tight unless you really go for it, splitting the paint and starting the rot. But it's your bus so go ahead and wreck it if you like, it saves going underneath it.
& that's precisely why I'd suggested that there is no need to screw across the floor at all, into voids or onto corrugations, from the top or the bottom. If you're really worried about it moving, Sikaflex 521 or 522 some timber batons to the "valley" in the corrugations in the metal floor, fill the spaces between the batons with your sheet insulation material & screw or bond the floor from above to the batons using brass self tapers or said Sikaflex, bobs yr uncle. Quote "..it's your bus.." & don't forget to tell us what you did & show us the pics
How much torque do you reckon would be need to secure 12mm plyboard, supported underneath by 20mm closed cell foam using ''practically positioned' M6 bolts?
I used the above method....and as the corrugations have been totally crushed beyond recognition, I find that there is now less drag when driving above 5 mph... Admittedly, I'm about to replace the entire floor as for some unknown reason it has completely rotted out...
We may be divided by a common interest, by I'm always right, regardless of what @zed may think.... (until I'm proved wrong, of course, at which point, I'll divert the victor's attention by using unnecessarily discursive language...)
I like it that you're prepared to spoil your bus/not fix the floor very well to prove a point that nobody really cares about.
Hah! I'll post pics later of the floor. Got some closecell insulation today (yesterday) so going to insulate tomorrow (today). Floor might take a little longer - need to decode all the advice first
Float the floor make them both happy.. Or 2 pieces of 6mm ple, Stagger the joints and glue together. Then float it. No need for screws won't move, job done,
I thnk the general idea is that if you roll the van it's best for the rear occupants if the furniture stays more or less attached to it. Thus a screw at the top of the furniture to stop it coming away from the side when you corner isn't really good enough and it helps if you start with a floor that's solidly attached to the van so you can follow on screwing stuff to that.
it's a speciality of mine....It's a technique often used by the SAS* as "badly orchestrated lash-ups, lacking ordinary care to knacker stuff"... or b o l l o c k s for short. *Saturdays and Sundays
They must have started doing it. Mines a 69 and there's no holes in the floor and has outer belly pans on. I've always screwed from above but makes sense doing from below. Although I would say there's more strength screwing into the metal rather than wood.
Apologies for the lack of pictures; I can't post replies or threads from my laptop for some reason. Can log in OK, but nothing appears in the reply box for me to type... Had to type this off my phone - can't access pictures off this though...
Yes thanks! Managed to get some up on here - decided to start a resto thread, so they're in there Not sorted the floor yet though! Lack of funds and time plus a desire to fit decent insulation are holding the project back at the moment...