Floor Building Question

[StandUpGuy]

I see lots of people building frames under the plywood sheathing. These frames lay on the trailer frames, elevating the sheathing off of the metal frame. Seems to me there is a lost opportunity for the metal frame to do some of the supporting of the sheathing and it also seems it is raising the floor height. Is this being done because of bolt heads sticking up from the trailer frame? I was envisioning having a wood frame at the same level as the trailer frame working in unison with it to support the sheathing. I was thinking this could minimize the amount of dimensional wood required and lower my floor height.

[GPW]

Stand , some people just like to overbuild things ...IMHO Seems the dimensional wood would be better served inside as you say ... Ply bolted direct to the steel ... Many ways that Cat's been skinned...

[StandUpGuy]

If I had welding capability I would think adding framing that way would be best. Short of that I would think cross members in wood could be bolted in place. Also I see a lot of wood cross members being laid flat rather than on end. This just defeats the purpose. This turns a 2x4 into the support ability of a 2x2. Actually less than. I would think a series of 1x3s on edge at the same level as the metal frame would be effective and light weight.

[GPW]

Actually , I never heard of anybody falling through the floor on their TDs ... Not yet anyway ... Don't believe all that bracing/reinforcement is really necessary at all , just the way it was done in the old days where the structural wood WAS the Trailer frame ...

Now I just noticed Eagle posted a question about floors Wider than the trailer ... Seems that's where the extra structural wood (or welded steel framing) would be useful ...

[StandUpGuy]

Actually , I never heard of anybody falling through the floor on their TDs ... Not yet anyway ... Don't believe all that bracing/reinforcement is really necessary at all , just the way it was done in the old days where the structural wood WAS the Trailer frame ...

I was thinking about 1/2" thick plywood with 1"x3" (on edge) cross members. 1x3 are very light and if they are close enough together they would make the 1/2" ply, solid.

[chorizon]

I built a frame under my floor so that I could have something for my walls to screw into. I suppose I could have done it differently, though.

[StandUpGuy]

I built a frame under my floor so that I could have something for my walls to screw into. I suppose I could have done it differently, though.

I don't think there is right or wrong. My particular desire is to build the tallest trailer I can to fit in my garage. If I can lower the floor by inches that gives me more internal height. I am also extending my floor width wise beyond the trailer frame. I will of course because of this be making some sort of framing. I just was thinking the framing could be at the same level as the trailer framing.

[GPW]

Sure would !!! I totally agree with you about using the bracing/framing upright ... Twice as thick is 8 times as Strong !!
Just as a thought , it would be much easier to drill upright 2"X4" s for the longer attachment bolts ... 1"X3" would require a jig of sorts to do those holes through the somewhat narrow (3/4" ) width ... Just as a concession to easier fabrication ... and the little extra weight is down low on the frame anyway ... Don't figure many TD'rs are really going for ultra lightness ... that with all the extra "stuff" they carry along ...

Easy , if not a bit pricy to just have some "wings" added to the steel trailer (welding/fab) Then you could bolt the floor directly to the steel for the Lowest height ... sometimes , fitting it in the Garage , inches count .... as I found out the hard way on my Big TD ..

[StandUpGuy]

Sure would !!! I totally agree with you about using the bracing/framing upright ... Twice as thick is 8 times as Strong !!
Just as a thought , it would be much easier to drill upright 2"X4" s for the longer attachment bolts ... 1"X3" would require a jig of sorts to do those holes through the somewhat narrow (3/4" ) width ... Just as a concession to easier fabrication ... and the little extra weight is down low on the frame anyway ... Don't figure many TD'rs are really going for ultra lightness ... that with all the extra "stuff" they carry along ...

Easy , if not a bit pricy to just have some "wings" added to the steel trailer (welding/fab) Then you could bolt the floor directly to the steel for the Lowest height ... sometimes , fitting it in the Garage , inches count .... as I found out the hard way on my Big TD ..

I do not have this all figured out yet, but the through bolting downward would simply be through the 1/2" plywood. I was thinking that the 1x3s woud be glued and screwed to the plywood only. If the 1x3s were forming a series of "squares" that they could be bolted to the metal frame on the horizontal.

[StandUpGuy]

I built a frame under my floor so that I could have something for my walls to screw into. I suppose I could have done it differently, though.

You are doing some nice fabrication there on your trailer. I had a look. Have you added a water tank and pump?

[absolutsnwbrdr]

There no one way that is correct. Everyone does it different.

I skipped the dimensional lumber frame under the 3/4" plywood floor. I made recesses for the frame bolts in the underside of the plywood floor. My walls and floor have absolutely no interaction.



Then my 3/4" uninsulated plywood walls bolt directly to the outside of the metal frame rails. You can barely see the few bolts along the bottom edge, but I countersunk the holes, filled them in after they were tight, and sanded them smooth.

[StandUpGuy]

There no one way that is correct. Everyone does it different.

I skipped the dimensional lumber frame under the 3/4" plywood floor. I made recesses for the frame bolts in the underside of the plywood floor. My walls and floor have absolutely no interaction.
Then my 3/4" uninsulated plywood walls bolt directly to the outside of the metal frame rails. You can barely see the few bolts along the bottom edge, but I countersunk the holes, filled them in after they were tight, and sanded them smooth.

Seems like you have done it in a very sturdy direct way. I like it. In my situation the floor will extend out past the metal frame about 8" so I must frame in some fashion.

Drilling for the bolt heads as you have done could be hard to locate. did you put chalk on the bolt heads or something, to get a location?

[absolutsnwbrdr]

Seems like you have done it in a very sturdy direct way. I like it. In my situation the floor will extend out past the metal frame about 8" so I must frame in some fashion.

Drilling for the bolt heads as you have done could be hard to locate. did you put chalk on the bolt heads or something, to get a location?

Yeah that overhang would require a different approach. To locate the bolt heads, I just placed the plywood on the trailer and whacked it with a hammer at each bolt location to leave a slight impression. I measured between those imprints to be sure, then started drilling.

[Wolffarmer]

3/4 inch ply can be built going past ( cantilevered ) the frame. Not sure how far I would have to do some eye ball engineering but just setting here 8 inches does not seem out of the question unless you build side walls from brick. You would then be on your own. I built my floor of 3/4 inch on spars past my frame. It is way way over built and added a lot of time, weight, height and cost that just was not needed. or will be used again. Even a good 1/2 inch ply can be cantilevered some and will be plenty for the floor of a TD. Heck, if the ply is not cantilevered past the frame I believe 3/8 of good quality ply would work with a few frame cross members for it to rest on. Which most trailers will have.

Randy

[StandUpGuy]

Seems like you have done it in a very sturdy direct way. I like it. In my situation the floor will extend out past the metal frame about 8" so I must frame in some fashion.

Drilling for the bolt heads as you have done could be hard to locate. did you put chalk on the bolt heads or something, to get a location?

Yeah that overhang would require a different approach. To locate the bolt heads, I just placed the plywood on the trailer and whacked it with a hammer at each bolt location to leave a slight impression. I measured between those imprints to be sure, then started drilling.

Good idea with the hammering. I will do that too!