Insulation troubles

[rhltechie]

Hey guys,

I am finally ready for floor insulation. I am at the big box store but I gotta tell ya, they ain't got much!! All they have are basically three types. There is one called r max tmatte plus-3 that looks like actual foam with a foil back. It says it's r value is only 2.9. Then they got the blue styrofoam that's Dow branded says it has 3.0 r value. Then they got something called polyshield styrofoam sheathing underlayment that looks like white styrofoam with a paper front and foil back. Says is 2.9. All of these I am not sure about. Here is another thing. The only one they have in 3/4 is the polyshield I believe. The depth of my "hole" where I am putting my I insulation is roughly 1 1/2 inches. Am I supposed to double up panels to get it flush or just put one panel in and leave open space? Can someone gimme a hand? Oh yeah. This is an open floor deal. No sandwhich. It's like what the gen ben plans refer to.


EDIT- So the other big box orange store on the other side of town has this stuff. It has a higher R value and I see a lot of the others using the "pink" stuff. This looks to come in 1" and 2". If I went with this stuff...would it be better to get the 1" and it not be flush to the bottom or get the 2" and have it sticking out?? I suppose it could be cut some way to make it less than 2" but that would be a real PIA.

[kirkman]

I'm of no help with your insulation problem. But I see you live in the Carolina's. So my question is why insulate the floor at all. I live in NY where it gets really cold and the only insulation I have is my mattress. It works OK for me and I have slept in my tear at -18. With a small heater of course.

[rhltechie]

I've had that comment before actually....and living in the south it gets REALLY hot. I am attempting to keep it comfortable hot or cold. I think my biggest worry though, as I doubt I will freeze to death is condensation. I've seen it with my own eyes in my house with my one uninsulated wall. Cold air outside meets warm/hot vapor inside...and the drips start coming...or under the mattress....I've heard of others on the board having that problem. So I am not sure its so much for comfort as it is to keep condensation from happening on the floor under the mattress.

[kirkman]

I had that same problem only once. After that I started sleeping with the vent open and a window open a crack and since then no more condensation. Hot or cold.

[Walt M]

Mandy, if you go to a more professional lumber yard you should be able to get 1 1/2" dow board or you can try a rubber roof supplier or installer, they have a product called ISO board. Most foam ins. should have an R-factor of 5 for each 1". Walt
'

[Sparksalot]

There's really no reason to go more than 3/4" for the floor, unless your walls and roof will also have the thicker amount.

[rhltechie]

thanks for the comments. My only issue with the lumber yard deal is that open at 8am and close at 4pm. No weekend hours. Just starting a new job it's going to be nearly impossible to get to one. I was hoping to not have to go that route but I suspected that may be the answer.

[BobR]

Go ahead and double it up for 1.5 inches. It will be fine.

[S. Heisley]

Hi, Mandy:

Even though I am a rookie, I am willing to give my thoughts, which may hopefully help. Unprotected insulation is going to occasionally meet with road hazards and campground rocks and stones. When it does, it is going to break up some and could hang down and maybe get ragged looking. I would think it would be okay to have the insulation inset a bit as that would allow your wood floor frame to act as buffer protection.

You may have seen other threads on this subject, where some people simply add a layer of insulation between the floor top and their mattress. (I believe I've read that both MadJack and Doug Hodder have mentioned doing it that way?) I've even seen some people use those black rubberized interlocking floor mats. Putting insulation on top of the floor like that would be easy to do and easy to replace, if it ever needed to be replaced. I'd do something like that, if I were building a teardrop instead of a half-standy.

Being Easter weekend, many people are probably off, enjoying something other than the forum. I imagine you will hear from more people Sunday evening or Monday.....)


Best Wishes & Happy Easter!

[rhltechie]

Hmmm... On top of the floor. Never considered that. As it's not really thick I don't think it would sacrafice too much room. More to think about I suppose!!

[dakotamouse]

We didn't insulate under our floor and we wish we had. We've had our tear out in winter and have had a problem with condensation under our mattress.

We got smart last fall. We found some foil sandwiched insulation, .75 thick, and layed it under our mattress. Problem solved. In spring we will take it out. We cut the insulation in 3 sections so it would easily go in and out of our door.

[madjack]

I'll offer my take on floor insulation...first off, I really don't like the way insulating the floor is described in the GenBen plans as it has the potential to create a "water trap" against the floor which even if well sealed with the black goop could induce rot...at one time, I did not see the need for floor insulation except for extreme 4season camping...I have changed my mind after having some condensation problems UNDER the mattress...SO, I added a sheet of 1" blue insul and have been very happy with that setup and it is what I recommend...you get the value of an insulated floor without the dangers of a water trap...the best of both worlds!!!!!
madjack

p.s. I also do my floors somewhat differently...I use a single sheet of ply, layed directly on the trailer frame...no sub frame and seal with 3 coats of epoxy and I connect the walls to the floor with 1X1/16aluminum angle as cleats........MJ

[rhltechie]

Thanks for all of your replies. I never really considered putting the insulation on the inside. It sounds easier maintenance.

[bobhenry]

I put 2 layers of 3/4 blue foam on my floor from the inside and then added a layer of 7/16 osb as the final floor. As the queen mattress covers every square inch of it I never bothered with a floor finish such as vinyl or laminate flooring. We have camped at -1 degrees with a -17 windchill and at 95 degrees in direct sun. It is a decision I made almost by accident. All I was really trying to do was eliminate the wheel well bumps I had created. I had some extra lexan so I placed a layer under the floor as a rock guard so insulating in the dry seemed a better choice to me.

[Nobody]

Everyone has their own ideas (& they're all good/valid). Do whatever works for you. I can say that insulating underneath the floor using the blue foam worked very well for me. My floor frame is 1 3/4" high & I used the 1" foam, placed while the asphalt coating was still somewhat sticky. I also used a bead or two of liquid nails adhesive & stapled 3/4" square 'battens' along the edges to help hold it in place. Almost 3yrs & more'n 6000 miles later I've seen NO evidence of any road damage & noted no other problems. I don't think I'd build without insulating the floor in some way -

This is the underside of my floor after installing insulation


Here's a current view of small amount of under floor insulation. The entire under floor all looks the same, no damage from road debris or water