Utility Trailer Floor

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Utility Trailer Floor

Postby LWT42 » Sat Jun 21, 2014 5:44 pm

Thinking about a first build, and I'm trying to figure something out.

I need to go light, both for fuel economy and because I don't have a heavy tow vehicle.

Most home builds seem to be built on a harbor freight or northern tool trailer, which has a metal frame, and then a wood floor frame on top of that.

Some have built custom frames to minimize the metal, and then used a "normal" 2x2 frame on top of that.

Has anyone gone the other direction? Bolted (lag bolts?) the plywood floor directly to the metal trailer frame? I know you'd need a 2x2 rim around the plywood floor to attach the walls, but it'd eliminate a fair amount of (redundant?) framing material, and it seems that it'd be very rigid.

Comments?

-- Lynn
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Re: Utility Trailer Floor

Postby working on it » Sat Jun 21, 2014 7:11 pm

LWT42 wrote:Thinking about a first build, and I'm trying to figure something out.

I need to go light, both for fuel economy and because I don't have a heavy tow vehicle.

Most home builds seem to be built on a harbor freight or northern tool trailer, which has a metal frame, and then a wood floor frame on top of that.

Some have built custom frames to minimize the metal, and then used a "normal" 2x2 frame on top of that.

Has anyone gone the other direction? Bolted (lag bolts?) the plywood floor directly to the metal trailer frame? I know you'd need a 2x2 rim around the plywood floor to attach the walls, but it'd eliminate a fair amount of (redundant?) framing material, and it seems that it'd be very rigid.

Comments?

-- Lynn
Yes, I went the other direction!; both as to bolting floor directly to frame, and in other things. I intended a light build, but ended up overbuilding. Part of it was using a lot of heavy hardware, 3/4" plywood all around (with lots of oak inner trim and bracing), and adding as many features as I could. I got carried away, I guess. Anyway, back to the basic structure: I bolted (3/8" carriage bolts)and screwed (TEK screws) and glued (Loctite PL adhesive) my floor to the metal framing (spray-undercoating the bottomside afterwards), then bolted (1/4"-20 stainless carriage bolts) and glued (again, Loctite PL adhesive) the walls to the floor and roof (the 3/4" thick walls sit on the top of the 4x8 flooring, leaving 46.5" inside sidewall width). I used steel corner braces, Simpson Strongtie angles, and PL adhesive for every inch of joined surface. Later, I also used PL as a caulk, to seal the seams. A link to what I used: http://www.tnttt.com/viewtopic.php?f=21&t=19442&p=1049201&hilit=tek#p1049201 Very strong, and very heavy. However, I still recommend the method, but if 1/2" or thinner plywood was substituted, with less added items (the main culprit) or the (probably) unneeded oak bracing, I might've ended up with a light trailer...probably not, I overdo things, as a rule. And, knowing this, I've still increased my trailer's loaded weight from 1438 lbs at birth, to 1767.5 lbs a year later. In for a dime, in for a dollar, the saying goes.... Good luck with your build!
  • 2013 HHRv,"squareback/simple" TTT, semi-offroad? 4x8, 2000+ lbs travel weight
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Re: Utility Trailer Floor

Postby LWT42 » Sat Jun 21, 2014 10:49 pm

working on it wrote:I've still increased my trailer's loaded weight from 1438 lbs at birth, to 1767.5 lbs a year later. In for a dime, in for a dollar, the saying goes.... Good luck with your build!

I can't exceed 900 pounds.
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Re: Utility Trailer Floor

Postby KCStudly » Sun Jun 22, 2014 12:04 am

Welcome!

Look here and follow the links.

Also, have a look at alaska teardrop's stuff. He knows how to build light. Even if you don't want to use his metal tube skeletal frame method, it is worth having a look at his methods.
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Re: Utility Trailer Floor

Postby LWT42 » Sun Jun 22, 2014 2:05 am

KCStudly wrote:Welcome!

Look here and follow the links.

Also, have a look at alaska teardrop's stuff. He knows how to build light. Even if you don't want to use his metal tube skeletal frame method, it is worth having a look at his methods.

Alaska Teardrop's stuff is art.

He uses a lot of metal. I'm far better with wood.

My thought, instead of making a trailer with the minimum amount of metal, was to use the metal frame from one of the common, generic utility trailers in place of the usual 2x2 frame under the floor plywood.

It wouldn't be as simple, elegant or light as the ones you referenced, but it'd be lighter than making a 2x2 frame sitting on top of a metal frame from Northern Tool.

-- Lynn
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Re: Utility Trailer Floor

Postby alaska teardrop » Sun Jun 22, 2014 4:55 pm

    Thank you both KC & Lynn for complimenting my efforts. I appreciate it.
    Lynn, I understand the fact that not everyone can make or have made a custom chassis. But in answer to your floor question, you might consider one aspect of my designs & apply it to a store bought trailer with wood wall framing as you propose. That is to attach a sheet of aluminum over the top of the trailer frame first (a 4'x8'x.050" sheet weighs about 23#). I use VHB tape & rivets, but there are obviously other ways to make the attachment. From there build the walls as you propose, bolting the 2x2 wall framing to the outer perimeters of the trailer frame. Once your cabin is built, lay on a full sheet of extruded polystyrene insulation (1", 1 1/2" or 2"). For the flooring surface I have used vinyl flooring, manufactured imitation wood flooring & 1/4" oak plywood.
    IMO, the advantages over the traditional method of which you mentioned are: lighter weight, no gluing, can be removed & replaced in case of damage, underside protection, a fully insulated floor with no thermal bridges and less opportunity for wood rot & moisture to collect under the mattress.
    Keep in mind that the floor of a teardrop is really only a place to lay the mattress & sleep on, not a dance floor. Well actually I've found this method is plenty stout enough to dance on too. :)
    Also, if you're going to use a store bought trailer, you might consider replacing the suspension with a torsion axle in order to avoid a number of issues that folks have encountered with store bought trailers. See Zach's thread on that: viewtopic.php?f=35&t=58078
    Fred
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Re: Utility Trailer Floor

Postby LWT42 » Mon Jun 23, 2014 1:29 am

alaska teardrop wrote:Keep in mind that the floor of a teardrop is really only a place to lay the mattress & sleep on, not a dance floor. Well actually I've found this method is plenty stout enough to dance on too. :)

Fred,

Exactly.

Now I just need to think about (and digest) this for a couple of days.

Thanks -- Lynn
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Re: Utility Trailer Floor

Postby Corwin C » Mon Jul 07, 2014 9:38 pm

I haven't started yet, so I don't have actual experience, however, for what it's worth ...

I'm planning on a 1/2 inch ply floor bolted (5/16" elevator bolts) directly to a 2" x 2" x 1/8" square tube frame perimeter with 2" x 2" x 1/8" angle cross members every 24" (the metal portion still is probably more than really necessary.) I'll wedge extruded foam between the metal cross members for insulation. With my substantial girth, I can make 1/2 inch ply creak at this spacing if I'm on one foot right between the cross members. If I hopped, I may be able go through, but I think it would take multiple hops. However, the only time that a teardrop would see this kind of point loading is while being built or if it were used to haul cargo. My solution is to place a second layer of 1/2" ply loose on the floor that will be removed when construction is done and the mattress is put inside. My walls will have thin engineered and pre-finished hardwood flooring (about 3/8" thick) sitting on the 1/2" floor and tied down to the frame with thin metal straps (think hurricane straps on 24" spacing?.) The outside will be 1 1/2" extruded foam laminated to the inner wall and covered with canvas and paint on the outside. The foam will extend to to bottom of the frame (covering the metal straps). The ceiling will be 1/8" hardboard glued and pin nailed from the outside into the inner wall to give the tear the shape I want and again laminated with 1 1/2" of extruded foam and canvas and paint exterior. Spars will be limited to high stress locations (door hinges, galley hatch, door framing, etc.) Interior bulkheads will be extruded foam with more of the hardwood flooring for finish and to provide support where fixtures need to be attached. There will also be some small blocking for exterior lights and so on.

I'm not sold on the harbor freight option of getting a trailer. I've watched many spend more time and money modifying and trying to get a HF trailer to work than it costs to get a custom one built to specification with higher quality axle, suspension, bearings, etc. I realize that this may be the only option for some, but if you can, I believe that the custom trailer is the best option when looking at the big picture and long term use.

Welcome and good luck on your build...
Corwin
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Re: Utility Trailer Floor

Postby bobhenry » Tue Jul 08, 2014 6:14 am

LWT42 wrote:Has anyone gone the other direction? Bolted (lag bolts?) the plywood floor directly to the metal trailer frame? Comments?

-- Lynn


Yep !

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Re: Utility Trailer Floor

Postby Andrew Herrick » Fri Sep 23, 2016 12:27 pm

There's a TON of information on the forum about options for framing the subfloor and floor. I'll leave others to discover all that wisdom :)

Here are some notes on hardware choices for securing the floor to the frame.

1) Lag bolts (aka, lag screws). Only good for structural wood-to-wood connections. Hot-dipped galvanized preferable. Usually have hex heads, so must be installed blind with a socket wrench.

2) Carriage bolts. Carriage bolts have a rounded head with a square shank. The shank is hammered into a round hole and locks the carriage bolt in place. The fastener is tightened from the bottom using a nut (lock nuts are preferred) using a socket wrench.

3) Elevator bolts. These are pretty similar to carriage bolts, only the header is wide and flat, like a washer. They're also more expensive. And whereas carriage bolts are available in Grade 2, Grade 5 and Grade 8 strengths at your local big box store, I'm not sure which grades elevator bolts are manufactured in ...

3) TEK screws (or equivalent self-drilling, self-tapping sheet metal screws). These usually come with a hex head with an integrated rubber sealing washer. They're great little guys, but not as robust as a true bolted connection, so you'll have to use more of them. More info here: http://totallynutsandbolts.com/tek_screws.html

Most teardrop floors seem to be secured using one of these hardware choices. I've even seem some that secured a wooden frame to a steel trailer using a combination of Simpson Strong-Ties (like rafter ties) and sheet metal screws, so use your imagination!

Just don't use drywall screws :p
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Re: Utility Trailer Floor

Postby les45 » Fri Sep 23, 2016 12:58 pm

I bolted my 1/2" plywood deck directly to the metal frame. There are pre-drilled holes in the frame just for that purpose. I used carriage bolts and cut a screwdriver slot in the head with a Dremel tool to keep them from slipping while tightening the nylon lock nuts. I wasn't worried about weight so I used a 2X4 along the sides for fastening the 3/4 plywood walls. You can see how I did it at my journal: http://tnttt.com/viewtopic.php?f=50&t=49333
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Re: Utility Trailer Floor

Postby RonS » Mon Jan 02, 2017 4:49 pm

LWT42 wrote:I can't exceed 900 pounds.


There's no place like foam......

(check out the foamie section if you need to stay light)
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Re: Utility Trailer Floor

Postby aggie79 » Wed Jan 04, 2017 11:44 am

Andrew Herrick wrote:There's a TON of information on the forum about options for framing the subfloor and floor. I'll leave others to discover all that wisdom :)

Here are some notes on hardware choices for securing the floor to the frame.

1) Lag bolts (aka, lag screws). Only good for structural wood-to-wood connections. Hot-dipped galvanized preferable. Usually have hex heads, so must be installed blind with a socket wrench.

2) Carriage bolts. Carriage bolts have a rounded head with a square shank. The shank is hammered into a round hole and locks the carriage bolt in place. The fastener is tightened from the bottom using a nut (lock nuts are preferred) using a socket wrench.

3) Elevator bolts. These are pretty similar to carriage bolts, only the header is wide and flat, like a washer. They're also more expensive. And whereas carriage bolts are available in Grade 2, Grade 5 and Grade 8 strengths at your local big box store, I'm not sure which grades elevator bolts are manufactured in ...

3) TEK screws (or equivalent self-drilling, self-tapping sheet metal screws). These usually come with a hex head with an integrated rubber sealing washer. They're great little guys, but not as robust as a true bolted connection, so you'll have to use more of them. More info here: http://totallynutsandbolts.com/tek_screws.html

Most teardrop floors seem to be secured using one of these hardware choices. I've even seem some that secured a wooden frame to a steel trailer using a combination of Simpson Strong-Ties (like rafter ties) and sheet metal screws, so use your imagination!

Just don't use drywall screws :p


I used trailer deck screws to fasten the floor to the trailer. Easy, quick, light and cheap.

Most people "over anchor" the floor. Keep in mind that your draw bar is held to your receiver by only a single 1/2" or 5/8" pin.
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