Cargo floor sound proofing under ply floor - spongy floor?

Hi,

As my interior is currently out, I am going to sound proof the cargo area and above the engine. I have packs of Silent Coat to get rid of the drubbing. My question is - as the cargo floor has a recess and most closed cell foam sheets are around 8 to 10mm thick, do I just fill the recess with the foam and then cover with a layer of 3.6mm marine ply over the top to full width? Will the ply floor become spongy and not support the cabinets?

What have others done?

Thanks

 

Devon's had the whole floor covered under lino, no issues with cabinets

 

I would have thought 3.6mm ply for the floor would be a bit thin ....you might even spilt it standing on it if you have foam under it.

I used 9mm ply to bring the lower floor level up to the level of the metal by the still ...if that makes sense. And then did the whole of the floor area in another single sheet of 9mm ply.

I'm not sure how much benefit you would get from adding the closed cell foam TBH, as the ply of the floor will give you some thermal insulation.

I don't think you will get too much drumming from the floor either due to all the strength from the top hats below.

If your determined to do it, I would only do the lower part of the floor to make it level, then use 9mm ply on top of that.

I'm sure you can get thinner closed cell foam than 8mm, I'm sure @paradox used something similar to camping sleeping mats for his

 

Silver backed closed cell laminate floor underlay is best, that comes in around 4mm thick. Use silver side down

 

Then top up with 6mm to fill in, then 3.2mm (like original floor) all over? A bit like @zed? I am worried about going too thick and the ali door strip won't fit.

Cheap too - much better than £300ish

Cheers

 

LD45 polyethylene foam is around 45kg/sq meter....this will be dense enough to support 6 mm Birch ply (and upwards) over the area you suggest....personally, I'd go for a less dense LD33 which can be installed thicker, but compresses more to fill the voids. You could then use 9mm ply....
Alternatively, you could use strips of medium density LD45 to top out just above the ridges, a thin ali foil overlay and then your ply/flooring....this would then be supported by the ridges rather than the foam


if you're feeling adventurous, you could shutter off the sliding door cill and install a liquid latex floor....I'd actually do this if I could be arsed to pull all the units and flooring out again....or if I ever do another campervan.

 

Ive not done mine yet
To be honest the van is more or less on hold untill i get this house finished

 

Would 9mm be too thick as a top layer?

 

9mm should be fine and will come up to the edge strip, it will be less likely to crack/split, especially if you have packed out the 'lower' recess of the floor



under that I have 9mm filling the lower section, you can just about make out in the pic below (doesn't go right to the edge of the van)

 

I used,
12-14mm rubber backed felt underlay and 9mm WBP ply , warm and sound proofed

 

My lower fill in was 6mm
Top was 3.2mm (or whatever thin ply is)
The 6mm is the important measurement for filling in the lower bits, it could be a total of 6mm of anything. Then the layer that covers the whole area will sit flat and on the threshold. How thick you want to be above that is up to you.

 

What ever you put under the floor , don't create air pockets as this form condensation and eventually rust

 

if you have access to a router, and a rebate bit, you can easily trim off the edge to the necessary depth so the trim will fit....


I measured for the thickness of the carpet as well, so it's a nice flush fit and the carpet tucks under the trim....it's the og Devon trim strip, so yours maybe different

 

Vanwurks do a tidy trim that's accommodates different thicknesses

 

with posh courtesy Leds if i remember rightly....

 

If you want that T5 look

 

Am I aloud to mention T5 on this forum

 

you mentioned it once and i think you got away with it....

 

That was close

 

I may try and sneak one in under the radar....in an unrelated post