SUV bed build out question

Bite the bullet, I lived on 3/4 ply for a year with no bowing issues, and almost no support in the middle of it.

I have lived the past 2 years on 3/4 with no issues. If you are set on 1/2 and worried about sag you can make small joists out of ply by stripping 2 in pieces and gluing/nailing.screwing them together and then frame the bed with them (ply perpendicular to the bed of course). You may save some weight this way but obviously some space is consumed.

With that said I lived 6 months on 1/2" OSB that had a support underneath that was part of some integrated drawers.

My son and I just built one in his Element.  Used 3/4" chipboard-- much stronger than plywood.  Used five round-capped PVC pipe for legs and pressure-fitted them into flat caps that were bolted to the chipboard.  Easy to put together and tear down and store.  Covered platform with carpet padding and carpet.  Instead of hinging a smaller platform to the front, we just built a separate smaller platform that builds up the same way and connects to the larger one when the seats are moved all the way forward.  I get a full 6'2" of sleeping space on the thing with plenty of storage underneath.  Screw eyes and two mini tensioners keep it from sliding around.  Two folks can easily sleep on top with no bowing.

Jonny d wrote:

My son and I just built one in his Element.  Used 3/4" chipboard-- much stronger than plywood.  Used five round-capped PVC pipe for legs and pressure-fitted them into flat caps that were bolted to the chipboard.  Easy to put together and tear down and store.  Covered platform with carpet padding and carpet.  Instead of hinging a smaller platform to the front, we just built a separate smaller platform that builds up the same way and connects to the larger one when the seats are moved all the way forward.  I get a full 6'2" of sleeping space on the thing with plenty of storage underneath.  Screw eyes and two mini tensioners keep it from sliding around.  Two folks can easily sleep on top with no bowing.

Thanks to everyone for the input. Looks like I'll be going 3/4 inch.

Jonny D, my dimensions in the Sequoia are a bit different than the Element so I'm going to go with a hinged front platform but I'm using lift-off hinges that separate so I don't need to always have the extra piece attached. Instead it'll ride below except when needed. I'm also going to split the front platform to match the 60/40 split of my rear seats. That will theoretically allow for someone to sleep stretched out while one of the back seats is in use. Because of the way my back seat folds down I've determined that it's better to use it as the base for the smaller platform (with a foam shim in between) rather than try to build legs around it.

I'm undecided about putting foam and/or carpeting on it. I think I'd rather have a clean wood deck and pad it as needed. But we'll see.

I'll post up some pictures here when I'm done. 

you can get 5/8"......

I did 5/8. I use 1 inch foot long conduit pipes with caps for legs (two up each side, one in middle, a removable one for the swing down section). No bowing. Really easy to put gear underneath, though something huge would require one of the conduits to come out temporarily which takes 10 seconds or less.

Jon Frisby wrote:

I did 5/8. I use 1 inch foot long conduit pipes with caps for legs (two up each side, one in middle, a removable one for the swing down section). No bowing. Really easy to put gear underneath, though something huge would require one of the conduits to come out temporarily which takes 10 seconds or less.

How big is the main section? My dimensions will be 51" by 48." I have the same kind of pipes with caps and was going to go 4 (roughly each corner) and one or two down the middle. 

AndrewArroz wrote:

How big is the main section? My dimensions will be 51" by 48." I have the same kind of pipes with caps and was going to go 4 (roughly each corner) and one or two down the middle. 

The whole thing is 48"x72" so I think it's 48"x48" 

One in each corner of the main section, one dead center of the main section (1 is better than 2 because it makes it easier to move gear around underneath), and then 1-3 female ends screwed to the folding section. I have receivers for three pipes for the folding section but I only ever use the center one. I've never had the corners bend on me and I get out of bed to pee twice a night.

Jon Frisby wrote:

The whole thing is 48"x72" so I think it's 48"x48" 

One in each corner of the main section, one dead center of the main section (1 is better than 2 because it makes it easier to move gear around underneath), and then 1-3 female ends screwed to the folding section. I have receivers for three pipes for the folding section but I only ever use the center one. I've never had the corners bend on me and I get out of bed to pee twice a night.

What kind of hinge are you using for the folding section? 

Just a three pack of hinges like these: http://www.doorcorner.com/3-12quot-hinge-with-58quot-radius-satin-n31258.html?utm_source=bing&utm_medium=ppc

Make sure your screws are properly recessed to prevent the hinges scraping against your mattress material

I built a two-piece platform in the back of my Volvo wagon that is stowed in the back most of the time so I can used the back seats.  I used 5/8" plywood, with a support in the rear section lining up with the division between the rear seats, and no support in the front.  Only 20-30 nights in it so far I would guess.  No noticeable bowing with two people, although I think the front section is starting to warp a bit from humidity.  Treated with many coats of teak oil; maybe should've ponied up for marine varnish or something.

Photos here: https://www.mountainproject.com/v/112270386

AndrewArroz wrote:

I'm going to try using these so I can take that section off entirely. 

https://www.pennelcomonline.com/us/us/Penn-Elcom-Lift-Off-Hinge-Nickel-P0644N/m-8752.aspx?PartnerID=10&utm_source=google&utm_medium=shopping&utm_campaign=UnitedStates

Oh fuck yeah I'm going to swap these in - that would be super useful

Todd Anderson wrote:

I built a two-piece platform in the back of my Volvo wagon that is stowed in the back most of the time so I can used the back seats.  I used 5/8" plywood, with a support in the rear section lining up with the division between the rear seats, and no support in the front.  Only 20-30 nights in it so far I would guess.  No noticeable bowing with two people, although I think the rear section is starting to warp a bit from humidity.  Treated with many coats of teak oil; maybe should've ponied up for marine varnish or something.

Photos here: https://www.mountainproject.com/v/112270386

Really nice. I like that cutout so your skis and other long items can go full-length. 

Jon Frisby wrote:

Oh fuck yeah I'm going to swap these in - that would be super useful

I bought a 4 pack and they seem a bit wobbly is the only thing. But definitely useful to be able to take off the extension. I'll let you know after I build it up and test it.

hmm, the thing is, the extension as I have it just folds over on top of itself, so you waste very little space. I'm not sure whether taking it off would add value or not. Let me know how it goes!

AndrewArroz wrote:

Really nice. I like that cutout so your skis and other long items can go full-length. 

Thanks!  I started out thinking I was going to copy this guy, but lucked out with dimensions and didn't need a hinged section: https://www.larszeekaf.com/my-stories-1/how-i-built-a-bed-in-my-car-in-3-simple-steps-video

The cutouts are definitely very helpful.  Biggest drawback with my system that I haven't solved is getting at the spare tire/tools, which are stored under the carpet in the back.  It's doable but pretty awkward.

Jon Frisby wrote:

hmm, the thing is, the extension as I have it just folds over on top of itself, so you waste very little space. I'm not sure whether taking it off would add value or not. Let me know how it goes!

My extension could just fold over itself, too. My logic, though, is that the extension will be about 25 inches and the back section is 48. So flipped back over it'll created a seam about 1/2 way across the back section. Which seem sub-optimal if I can avoid it and just throw the sections below decks or in the garage when not being used. 

Plywood, when we were kids we would of loved to have plywood.  My father use to make use sleep on sheets of discarded sandpaper covering the broken glass in the ally we lived in.

AndrewArroz wrote:

My extension could just fold over itself, too. My logic, though, is that the extension will be about 25 inches and the back section is 48. So flipped back over it'll created a seam about 1/2 way across the back section. Which seem sub-optimal if I can avoid it and just throw the sections below decks or in the garage when not being used. 

Another option I toyed with is making hinges on both the front and back, so 18 inch hinged section, 36 inch middle, 18 inch hinged section, so it folds to 36 inches. This also makes gear more accessible but you have to reconfig the legs a bit