adding floor insulation

[bmacke]

Ok, after reading many posts on the subject I think I'm going to add insulation to my floor. I'm still at a point where I can remove the floor and flip it over, so it shouldn't be too hard.

The question is... I sealed the bottom with the black goo months ago. Will more black goo be enough to securely attach some of the blue board insulation? I feel I'll need a good bond between the old stuff and the new stuff.

I'm also thinking of coating the blue board with epoxy before install to 'harden' the road side. I think that will help me practice with epoxy and lessen road damage.

Thanks for all your help.

Brian

[Miriam C.]

Epoxy is expensive but go for it. Don't know if you will really need it over insulation. Truth is you can buy lots of insulation for the price of epoxy.

You need to use some screws and fender washers to hold the insulation on. A good bond won't last as long and the wind might pull it loose.

[dmckruit]

What I would do is tack the blue board to the underside. Then cover over with a stiff mesh screen. Once the screen is anchored in place, I would then coat the whole thing with roofing patch compound.

Cheapest and easiest way.

[madjack]

...be carefull of creating a water trap under your tear...have you considered, just placing a sheet of insul between the mattress and the floor...tis what I do.........
madjack

[bmacke]

Madjack- I noticed that yourself and others had done that. I was hoping for a permanent/ built in solution. I know the way I (don't) clean and placing something under the mattress will be a dirt catcher for me.

Am I correct thinking that if I re-coat the bottom with black goo and press the insulation into it that I shouldn't be creating a water trap? I guess I will need a secondary means of attachment though.

[kennyrayandersen]

Try this thread where it was discussed in depth.
http://tnttt.com/viewtopic.php?t=28899
Condensation is caused when warm moist air meets a cold surface. The now suddenly cold air that just hit the cold surface cannot hold as much water at the lower temperature so you have this teeny tiny rainstorm and the cold surface gets wet. Eventually you get a puddle.
Summer
If you A/C the inside the you could get wet on the bottom of the floor (outside) on a hot muggy day if the floor were not insulated or warm moist air was able to get to the underside of the floor because you had big gaps. As long as the insulation in the ‘compartments’ between frames without a bunch of gaps, then you won’t have condensation problems, but you could get water from a wet rainy road getting forced up there; so, if you packed the insulation in there tightly, and closed out the bottom of the floor with 1/8 thick ply wood with the black goo, you eliminate all of those problems.
Winter
You breathe hot moist air in the tear with not enough ventilation (ventilation brings in drier cold air) and if the floor is not insulated and the mattress doesn’t entirely cover the floor, then water will condense on the floor (or walls if they aren’t insulated). If you put insulation under the trailer the floor won’t be so cold that water condenses on your floor. The key is also to let in some fresh dry cold air anyway, so that condensation isn’t as prone to happen in the first place.

[Ed K.]

As long as the insulation in the ‘compartments’ between frames without a bunch of gaps, then you won’t have condensation problems, but you could get water from a wet rainy road getting forced up there; so, if you packed the insulation in there tightly, and closed out the bottom of the floor with 1/8 thick ply wood with the black goo, you eliminate all of those problems.

Kenny,

I am considering making my floor with 1/2" plywood on the top side with a 1x2 frame attached to the bottom of the 1/2" plywood so I can put insulation in the floor followed by 1/8" plywood on the bottom which would get the black goo. I don't plan on doing any winter camping but will likely put an AC in the TD. Does this floor design sound like it would work?

Thanks,
Ed

[madjack]

As long as the insulation in the ‘compartments’ between frames without a bunch of gaps, then you won’t have condensation problems, but you could get water from a wet rainy road getting forced up there; so, if you packed the insulation in there tightly, and closed out the bottom of the floor with 1/8 thick ply wood with the black goo, you eliminate all of those problems.

Kenny,

I am considering making my floor with 1/2" plywood on the top side with a 1x2 frame attached to the bottom of the 1/2" plywood so I can put insulation in the floor followed by 1/8" plywood on the bottom which would get the black goo. I don't plan on doing any winter camping but will likely put an AC in the TD. Does this floor design sound like it would work?

Thanks,
Ed

I would find this much more acceptable than the insul, by itself, simply pressed into the bottom "goo"...keep in mind that my "inside" application is a "fix" for a problem I caused for myself..........
madjack

[kennyrayandersen]

As long as the insulation in the ‘compartments’ between frames without a bunch of gaps, then you won’t have condensation problems, but you could get water from a wet rainy road getting forced up there; so, if you packed the insulation in there tightly, and closed out the bottom of the floor with 1/8 thick ply wood with the black goo, you eliminate all of those problems.

Kenny,

I am considering making my floor with 1/2" plywood on the top side with a 1x2 frame attached to the bottom of the 1/2" plywood so I can put insulation in the floor followed by 1/8" plywood on the bottom which would get the black goo. I don't plan on doing any winter camping but will likely put an AC in the TD. Does this floor design sound like it would work?

Thanks,
Ed

AND, if you glue the plywood to the foam it's super strong. Either way that should work fine. You may have to put in some local reinforcements where you have loads introduced like at the axle (you could put a 1x2 in at that location) or other point load (concentrated load). Otherwise that’s pretty much how I’m doing mine – I’ll have 1x2 cross members buried in the sandwich at the galley wall (so I can join the galley wall to the floor) and at the front where the tongue hits the vertical front wall (to attach the tongue to), and maybe one more at the axle (to spread out that vertical load). Otherwise it will be framed out with 1x2s.

[bobhenry]

My very 1st build I got it right. I made a 2x4 halo around the floor. With the 2x4 standing on edge I cut a rabbett in the top and bottom inside edge it was cut halfway to the center (3/4") deep and relieved to accept the depth of the 1/2 " osb that I was planningto use. I got fancy and cut the halo at 45 degrees so no end grain would show. Now the insert of osb was cut to fit in the rabbetted recess and glued and screwed on the bottom. I cut 2 intermediate joist ripped to 2 1/2" and placed them inside the torsion box. I then filled the cavities with 5 layers of 1/2" blue foam. As it turned out the joists were really overkill. The top was glued and screwed to the halo also. This floor is strong. Corner to corner it will not flex and you can park a truck on it. Yet it remains fairly light. The 2x4 perimeter give you plenty of meat to attach sidewalls to either on the face or the top of the 2x4. This type of floor would be especially valuable for those folks trying to make a convertible trailer ( flatbed one day / teardrop the next)

[Roly Nelson]

My woody has a 3/8 inch floor, and below it 3 1/2 inch fiberglass insulation batts were installed. This was covered with 1/4" plywood on the whole bottom, which was then shot with Line-x truckbed liner. If I were to do it again, I'd leave off the insulation and the lower plywood layer as well as the Line-X. I feel a mattress is insulation enough and with the insul trapped between 2 layers of plywood, it is just a perfect area to trap moisture. The Line-X is too heavy, and roof mastic/goo would have been adequate. Just my 2 cents.
Roly

[boardhead]

I used rigid foam insulation on the underside of the floor of my tear as follows.

1. Built the floor using 1/2" ply and 2x2 stringers.
2. Covered the underside with asphalt emulsion.
3. Glued and screwed the insulation between the stringers. Glue was liquid nails, screws were drywall screws with big, fat washers.

I did NOT cover the underside with ply, or anything else. When you look underneath, you see the insulation between the stringers.

I've used the trailer heavily over the past three years and have had no problems with moisture or condensation, in temperatures ranging from 20F to 100F. The insulation has not deteriorated or come loose at all. In fact, it still looks as clean as the day it was built.

[bmacke]

so, boardhead, you haven't had any problems with road debris damage to the insulation? I usually can't move it around the shop without damaging it.

brian

[boardhead]

I've taken it on 250mi each way trips where it rained the whole way, with no damage. I'm retired, and addicted to windsurfing, so from April to the end of September, I take it to the Columbia River Gorge, 65 mi each way, every week. Absolutely do deterioration or damage at all.

Adding another cover or coating underneath, in my humble opinion, is unnecessary.

Good luck with your build!

[chorizon]

I posted this same question a while back. Like boardhead, I used the board insulation. Here's the link to that thread, which supplied me with enough info to feel comfortable about going that route.

http://www.tnttt.com/viewtopic.php?t=22348&start=0&postdays=0&postorder=asc&highlight=insulation+attach