Using your trailer frame as your deck...mostly?

[DMcCam]

I've been thinking about squeezing a few more inches for interior space. Could you build your trailer frame out of 2" square steel stock then weld a thin sheet of say, stainless steel to the bottom of your trailer frame, insulate the voids, then attach a 1/2" or 3/4" deck? That way you could have a sealed bottom for weather, an insulated floor and a bit more room in the cabin. Thoughts o' experienced builders?

Thanks, Dave

[High Desert]

Good question Dave. I'd like to hear the thoughts on this too, as I've been thinking along similar lines. Do you have to build a torsion box floor? Seems to me a welded frame already is one, and if the walls overhang the frame...

[len19070]

Many if not all of the large "Box" RV Trailers do it that way, however they seldom use square tube frames.

And that's where there may be a problem. Inside the square stock will be uninsulated. Aside from the fact that the uninsulated steel will be a cold spot, Your mattress over the floor should clear that up, the steel will sweat and create condensation.

Now if the tubes were filled with an insulation it may cut down on this condensation.

And a layer of something that won't rot, be it plastic,Tyvek or just a real good coat of tar (even though that wood will not be exposed to the weather) was put between the steel and the 1/2..3/4" deck to block the sweat, I think you would be better off.

Keeping the body low is important for the overall looks of the trailer.

Happy Trails

Len

[vwbeamer]

Use 2 inch angle 2X2 tubing is over kill anyways, so is 2 in angle for that mater.

[bobhenry]

I've been thinking about squeezing a few more inches for interior space. Could you build your trailer frame out of 2" square steel stock then weld a thin sheet of say, stainless steel to the bottom of your trailer frame, insulate the voids, then attach a 1/2" or 3/4" deck? That way you could have a sealed bottom for weather, an insulated floor and a bit more room in the cabin. Thoughts o' experienced builders?

Thanks, Dave

I tossed a bit of extra lexan on top of the frame . Then built the floor from 3/4 osb. I added a skirt of 2x4 ( glued and screwed every 4 " )
to attach the sidewalls to and also to cover the frame. It all just layed on the frame untill I added the foam insulation inside and a 7/16 " osb sub floor them I drilled and bolted at 8 points thru the frame and the entire sandwich with monster fender washers inside with carriage bolts and double nutted with lock washers underneath.

[flip18436572]

As someone completely new to this board, why not make the outside frame out of 2x2 tubing, and then use 2" angle iron for the cross supports at 2' intervals. Then you could put on a thin piece of metal underneath (pop rivet or welded). The you could put in foam insulation between the 2" angle and seal with caulking if you wanted to make it even tighter. Just make sure that the angle is on the top, so You have something to screw your floor to.

Then cover that with the wood floor you want for your TD. Then build from there.

Just an outsider view and thought.

[alffink]

Stainless is very heavy compared to aluminum and were talking about under the tear, I have run on many dirt roads, in the rain, in the snow for three seasons now and the underside of the trailer is "clean" gets very little water, dirt, mud, etc. thrown up underneath

I just have the rigid foam sheets attached to the floor, which has been coated with asphalt slurry, aboslutely no problems, rain falls down not up, the underside of the trailer is pretty well protected from the weather.

no need to try to seal and eventually trap moisture inside.

[flip18436572]

I just have the rigid foam sheets attached to the floor, which has been coated with asphalt slurry, .

How does the rigid foam stay connected to the trailer? Do you have pictures of you trailer in the process of the build? I know that glue does not hold forever, and it seems to fail in the changing winter temperatures of Iowa. Thanks.

[alffink]

The foam is cut to have a press fit.

Then there are a few widely spaced deck screws with fender washers just to give added support, but I don't believe the screws and washers are seeing any load yet.

[vwbeamer]

I had a 16 ft landscape trailer made of 2 in angle, i would put tractors and commercial mowers on it weighed 1200lbs, or more.

I'm not sure what some of guys are trying build, but you could save a lot of weight and money by using smaller steel.

[Nobody]

I just have the rigid foam sheets attached to the floor, which has been coated with asphalt slurry, .

How does the rigid foam stay connected to the trailer? Do you have pictures of you trailer in the process of the build? I know that glue does not hold forever, and it seems to fail in the changing winter temperatures of Iowa. Thanks.

I used pretty much the same method as Al Fink during my 2006 build. In Aug 2008 I finally 'plumbed' my TD for the PetCool A/C, & took the following pic of the underside. The TD at that time had been pulled more'n 6K miles over all kinds of roads'n trails, paved, unpaved, & muddy potholes, in every kind of weather. You can see that the foam insulation is still nearly pristine. As of today, & another 4K+ miles, it still looks the same. The A/C plumbing has actually picked up more 'dirt' than the trailer chassis or the bottom of the floor. I also did like Al says, cut the foam to be a 'press fit' on the still 'sticky' ashpalt coating, then I went a step further & cut small 'batten's from 3/4" square stock & stapled them to the 2X2' floor framing. Nothing has moved yet -

Underside of TD in Aug '08 after 6K miles


Underside of floor undercoated & insulated -

[High Desert]

OK, tell me what everyone thinks of this idea; for the main deck- a sheet of interior grade FRP (similar to bobhenry's lexan solution) and a sheet of 3/8" ply directly on top of the frame. Then a second sheet of thin FRP on the bottom side like Dave mentioned. Insulation in between. Where I'm be using an HF frame with channel instead of tube that should negate most of the sweat factor. And as the steel would be against the FRP, it would also work on tubing...I think

[synaps3]

Shaun -- that's way overkill!

The FRP layers will add nearly $100 to the cost, and not really do anything to insulate.

You could just take a layer of 1/8" ply, build a frame on it with insulation throughout, and top with 1/4" ply.

I have no idea why you'd ever use 3/8" ply on a normal tear build. 3/8" ply backed with any sort of rigid frame could hold a car -- you only really need to hold 1/10th that weight.

[High Desert]

Shaun -- that's way overkill!

The FRP layers will add nearly $100 to the cost, and not really do anything to insulate.

You could just take a layer of 1/8" ply, build a frame on it with insulation throughout, and top with 1/4" ply.

I have no idea why you'd ever use 3/8" ply on a normal tear build. 3/8" ply backed with any sort of rigid frame could hold a car -- you only really need to hold 1/10th that weight.

I can get the FRP for free is part of it. The other part is that there would be no extra wood frame on top of the steel one, so that weight is eliminated. The 3/8" thought is mainly from Andrew's Pico Light design. Maybe 1/4" would do. And then just an FRP sheet under the frame, with the top sheet back coated for moisture protection .

I'm like lots of us I guess, I want it all, and don't want to pay the weight price at the same time

Edit* just for clarity, I refering to the 1/8" thick fiberglass reinforced plastic sheets, not Fiberglass reinforced plywood; both are often refered to as FRP*