Securing Sub Floor

[user 29503]

My sub floor is the sections of 3/4" plywood.
I have been fervently cautioned not to screw it down.
I've also been told that once all the weight is on top of it, it should stay down with a snug fit
I have Kilmat covering 90% of the floor or whatever the manufacturers recommendation was (I received an email form a customer service representative who told me to do that)

Will liquid nail, over the Kilmat and the weight of my shit suffice, or do I need to screw it down anyway, all be it in some carefully minimalistic fashion?

 

[cherterr]

I always base those sort of decisions on what I call: “The Accident Criteria”:
If it’s probably only going to come loose in such a severe accident that I’d probably die anyway- I don’t worry about it. Everything else get secured.

 

[user 29503]

I always base those sort of decisions on what I call: “The Accident Criteria”:
  If it’s probably only going to come loose in such a severe accident that I’d probably die anyway-  I don’t worry about it. Everything else get secured.

Thank you for both of your replies.  Yeah it's either roll around in the mud with a bunch of neurotic measuring to make sure I don't rupture something, or I can just liquid nail it and improve my chances of getting the hell out of here.  Was worried the kilmat might make the 3 separate sections uneven from one another, but if I weight everything down with cinder blocks I figure gravity will win. 
 Be well.

 

[gizmotron]

I glued my firing slats to the floor using construction adhesive knowing that vibration would eventually work it all lose. But what I did was use interlocking joints where all the connections occur. There are pictures of this in my van build thread. I used two interlocking pieces of 3/4 inch strips, screwed together, but not to the floor and glued them down. Later I used 1 1/2 " Foamular pink rigid foamboard between the slats. So this cage of slats and foam are under my then 5/8" CDX plywood. It's all one unit. The entire thing is a single sub-floor all screwed and glued together. It can't go anywhere.

https://vanlivingforum.com/showthread.php?tid=43988&page=4

 

[Calaverasgrande]

My floor is glued and bolted to a couple 2x2 or 1x2, which are in turn glued to floor.
It's also cut to fit very tightly into the space. So there is no way it can shift forward. The pillars, recesses and bulges of the walls kind of lock the sections in place.
In addition I'm using rivet nuts in the factory cut holes in the walls of the van. I secure wood to the walls, then more wood, coroplast or plywood to these firring strips. This is in turn connected to the floor on both sides. So even if I roll the van, the floor isn't moving.
At this point I'm more scared of my unsecured cargo than the floor.
I'd really advise everyone doing DIY builds to check out rivet nuts.
Way easier than the way I used to do it with carriage bolts, sheetmetal screws and drilling holes all over. Even if you do drill your own holes, these things are great. They are very secure.

 

[MrNoodly]

I've also been told that once all the weight is on top of it, it should stay down with a snug fit.

Even without a snug fit. But if you're concerned about side-to-side shifting, one bolt through each panel should do the trick. No trick measuring required, just slide under the van, reach up between the stuff under there and drill upward.

And I hate to break it to you, but Kilmat or other sound deadening is pointless if you're putting something else on the floor, especially something as thick as 3/4" plywood. And then you're putting other things -- boxes, bins, bags, jugs, duffles, and so on -- on top of the flooring. All those things block noise. And hold the floor in place.

 

[flying kurbmaster]

I have heard that on here, not to screw down your floor but never heard a good reason not to. Some people might think that you may invite rust but that is a long way down the road and could be avoided with a bit of grease or sealant down the hole before screwing a galvanized or stainless screw. A Canadian women on this site several years ago had a serious accident, hit a guard rail on ice if I remember correctly. Anyway she had a good warning about securing things as she was surprised how everything went flying. If you have cupboards or things screwed to the walls sitting on your floor you might be ok otherwise I am not afraid to screw into my floor, you don’t have to fill it full of holes but a few screws or bolts seems a good idea to me.

 

[user 29503]

And I hate to break it to you, but Kilmat or other sound deadening is pointless 

Thanks.  The quantity I ordered ended up giving me extra, when I emailed the vendor about something else, they were adamant I put it on the floor.  They made the stuff, so I figured, what the hell. Anyway, will do.  Thanks.

 

[Calaverasgrande]

And I hate to break it to you, but Kilmat or other sound deadening is pointless if you're putting something else on the floor, especially something as thick as 3/4" plywood. And then you're putting other things -- boxes, bins, bags, jugs, duffles, and so on -- on top of the flooring. All those things block noise. And hold the floor in place.

Disagree.
Plywood is stiff and dense. It is a good sound conductor.

Sound deadening material will help to decouple the stiff dense sound conducting materials from the stiff dense steel of the body.
Source, I went to college for audio engineering and worked as such before I got into IT.
Used to help clubs design acoustics to help prevent noise complaints.

The best noise insulator between two surfaces is actually air. But second best is some kind of limp mass. Butyl tape is often used. Or some other similar viscous material. There are lots of overpriced products you can buy!
A cool trick we often use in acoustics is to layer several kinds of material.
sheetrock, Fiberglass batting,  foamboard, vinyl sheeting, sheetrock.
Sound vibrations incur a loss whenever it transitions from one material to the next. Due to the change in density, there will be refraction and phase changes. Counterintuitively you get more isolation with layers of dissimilar material than layers of sheetrock or wood. Hard materials conduct low frequency better than air, with only a partial transition loss. Less stiff material allows the sound to be 'eaten up' by the work of moving the soft material around. The work converts the sound energy into small amounts of heat energy.

 

[crofter]

Mine is bolted down using the D-ring cargo bolts that came with the van.

My flooring cleats are screwed to the backside of the plywood, and the cleats anchor the build out.  So I did want it bolted down to secure all that.
-crofter

 

[user 29503]

Based on the information below, I've chosen to screw it in, using a minimum amount of screws, and my cabinetry and weight of my things will also aid.  I'm comfortable with that solution. Thanks everyone.