Homemade Transformer Idea - what do you think?

[vwteleman]

Dave,

I re-read your post from this morning, and I see you did know the height, but were asking if SMB changed anything. Sorry, hope I didn't sound too flippant.

I am 6'1", and head clearance in my van is enough but not generous when sitting on the "50" bench (with the top down). Note that I have a GTRV top, which is lower profile than the SMB penthouse top. I would guess that the SMB top provides more headroom compared to my top, and definitely compared to the stock van roof. Also, I estimate I have about 1½" in my floor (insulation, plywood, rubber flooring).

Cheers,
Brent

[dave_in_delaware]

Oh, OK. No problem.

I was planning on NO top at all (stock van roof), but we'll see what happens and what I find when I'm ready to shop.

As for your floor insulation, do you know if it is only insulated between the "ribs" of the metal floor, with the plywood screwed directly to the top rib? Or is the insulation thicker than the top of the rib line?

[vwteleman]

The ribs were filled in first, then additional insulation was placed on top. My floor is (I'm guessing dimensions): ½" insulation, ½" plywood, rubber loncoin flooring, measured from top of ribs.

I'll see if I took a photo of the floor during construction. I've been meaning to post a thread on my build for a couple months now. Maybe someday...

Brent

[dave_in_delaware]

So you have 1/2" of insulation above the top of the ribs? And the ribs are how deep? 1/2" also? Or more?

I'm trying to find that info so I can properly design my flooring system. My thoughts are: infill the ribs w/ high density extruded polystyrene insulation until it's flush w/ the top of the ribs. THEN add another 1" extruded polystyrene rigid board insulation. 1" of that stuff gives an R-value of 5 IIRC. 1/2" plywood on top of that, and carpet.

What kind of insulation did you use?

[vwteleman]

As I said, I was estimating the dimensions, so am not sure. But I do know the ribs were filled with insulation followed by additional insulation across the entire floor. Hopefully, I have a photo I can post.

Not sure of the type of insulation (I will check with the shop), but it wasn't XPS - your plan sounds like a good one.

Brent

[dave_in_delaware]

Originally Posted by vwteleman

... your plan sounds like a good one.

I certainly hope so! I did some research on various types of RV construction and various manufacturers, as well as many DIY projects out there, and concluded that XPS's various characteristics make it a perfect candidate. My floor design should provide an adequate "base" for everything else:

||||||||| high-traffic carpet
========= 1/2" plywood
-+-+-+-+- 1" XPS layer
-/\-+-/\- 1/2" (or whatever it is) XPS between ribs

I'm guessing the fastening system would be either long sheet metal screws OR bolts through the floor system into the ribs, maybe 12" on center (doubled-up at edges). Assuming I could access the bolts under the van.