Subfloor material

[dreadcptflint]

I see that alot of people using the black goo for the undercoat of their trailer. I was wondering if anyone has used Composite Lumber or Cedar and skipped the undercoating?

[bobhenry]

Composite lumber ???

Structural composite lumber is used in residential and light commercial building as long span high capacity beams. Laminate veneer lumber ( LVL)
is a giant plywood beam. Parallel strand lumber (PSL) Is strands of lumber oriented along the beam for even higher strength and larger sizes.
They are heavy and swell like a dead racoon on a hot summer day when exposed long term to water.

If you are talking about the plastic lumber and other than wood composits there are a couple that hold up rather well. There is a composit rubber 4x8 sheet material ( $50.00+ per sheet) that would be totally impervious to water. Medium density overlay MDO board holds up well in the weather as well.

If you don't like the black goop just use a exterior grade plywood and coat with polar seal or cool seal its a rubberised elastopolymer coating that seals and protects and is practically indestructable once it is dry, Won't rub off or chalk up and drys completely yet remains flexible. The high solids contents fills cracks and wood joints so water has no place to hide.

[dreadcptflint]

I am talking about the plastic like stuff that has been showing up for deck materials the last couple of years. I know the stuff is a little costly (2-3 times the cost of traditional lumber) however it appears to be very low maintence and tough.

[bobhenry]

Ok ..Trex and other trade names. I am not aware of it being available in sheet form so are you going to use the 6" wide boards. If so will you seal the joints or just let the insulation board be your moisture barrier. ???

[aggie79]

Need to be careful about two things with composite lumber:

1. It does not have a lot of flexural strength and can't span too great of distances. It differs per product, but 16" to 24" is the maximum span.

2. Its thermal expansion rates are much more than dimension lumber, so if you're using it for the floor deck, you'll need to think how this will affect the walls, bulkheads and roof.

[dreadcptflint]

I was thinking of doing the six inch and doing a simple tongue and groove. The seems shouldn't be too much of a problem since I was thinking a construction adhessive. A bead of silicon between the floor and side panel should do the trick.

Now the expansion issue does have me thinking twice about using the stuff. I don't want flex in the structure and with the heat that gets well into the 100s in the summer this could create a serious problem down the road if it expands too much.

Now we are getting to the good stuff, has anyone used or seen this stuff used on a teardrop?

[madjack]

...unles the manufacturer has a specific adhesive/sealant for it, I bet you will have a hard time finding one that will stick/seal it........
madjack

[alabubba]

This is an interesting thread...there is probably a small business opportunity for recycling coke bottles into pre-formed teardrop subfloors and the like, which could have inserts molded in for making fastener connections.

[dreadcptflint]

...unles the manufacturer has a specific adhesive/sealant for it, I bet you will have a hard time finding one that will stick/seal it........

Very good thinking Madjack, the stuff that I saw was very resistant to paints and stain so adhesives might be a problem.

[Captain Obvious]

I have read a lot and have not posted but I would say you want a certain amount of flex in your build. If it is to ridged and has no give it will crack and then you have those problems. If the rate of expansion is not comperable between materials used then you run into the problem of it breaking the seal of the adhesive. It is something that will probably not be evident right away but could cause problems down the road. Similar to what ice does to roads, rocks and other concrete structures in the north. Small cracks get larger due to diffences in expantions. Good luck.

[dreadcptflint]

Captain Obvious,

Thanks for pointing out a poor choice of words on my part. I am of course referencing my use of flex. The expansion and contraction of the materials is what has me concerned. I know that there is a little expansion with wood. I however do not know how much expansion these new plastic lumber have.

Since I am dealing with a temperature range of 110 to 0 using something new worries me a little. (I am lazy and cheap and the thought of going in and tearing out a floor after a year or two to replace it doesn't interest me).

From what I have seen of the used trailers in my area. The second area needing replaced is the floor. (The first being water damage around poorly sealed vents and windows). If going to a sythetic saves me some head ache down the road then I will go there. I would go to metal however I don't really want to go that way.

I have built enough structure to know that I want a firm structure. If you have ever seen the cracked tiles on a undersupported floor or a sagging drywall ceilling then you will understand where I am coming from.

[S. Heisley]

Hi:

I've researched and experienced enough to be able to say that the spacing between composite boards (Trex-type stuff) on decks is not just to allow the water to drain. It is also for expansion purposes. If the boards were not only butted but also tongue and groved, there's no telling what might happen. Composite boards are also heavier and more expensive than their more wooden counterparts.

Here's idea for you: It seems a lot of people swear by Dr. Rot's CPES (Clear Penetrating Epoxy Sealer). I have written to Dr. Rot, asking if I could use CPES on my wooden deck, followed by the customary black underlayment sealer used by most folks. The answer was that, if the CPES was applied first, allowed to dry and then sanded to provide enough 'bite' so the underlayment sealer would hold, the combination would work. If it does, I would think it would give twice the protection against moisture and rot.

Whatever your final decision, I wish you success.

[dreadcptflint]

Howdy,
Yeah, I will definitly be sticking to good old fashioned wood for the subflooring. It's too bad that this stuff expands too much to be useful.