2013 Mirage XPO 6x12- Mt Air Express

[Rainier70]

Great. Glad it is working for you. It sure makes a difference in my camper.

I think I need to put some screen on its sides for when I have the grandkids with me. They are old enough to know better than to touch, but better to be safe.

[Mike S]

I went camping for several nights over the weekend of Apr 12th. My heater ran great except for some minor wind problems on one of the days. The wind was gusting at about 40+ mph, and it would blow out the flame if I had it on really low. I have a "high wind" cap on order so I hope it fixes that issue.

The main thing that I noticed was just how much cold was coming through the floor. It was pretty cold out at night, and I kept my heater going. It was about 65 deg in the camper when I got up and about in the teens or twenties outside. What I noticed was that where I had put my waders to drip over my shower pan the pool of water in it was frozen. A water bottle that I had left on the floor was partially frozen also. Both of those were frozen within 3 feet of the stove and when the temperature at 3 ft high was 65 deg. I know that I could put a fan on and stir the air a bit more, but it really shows me how much of a heat loss the uninsulated floor is.

I have since then started to insulate my floor. I am using 2in "pink" foam board. I am covering one side of the foam with the canvas-glue-paint coating that the foamie builds are using. I decided to try this method since I already had most of the supplies for it. I had to buy the Harbor Freight canvas at $15, but that was about it. The paints, glue, and etc are leftovers. If I had to buy everything, it would be getting close in cost to using the frp panels. It does take awhile though to glue and paint the canvas covers on.

Once the panels were dry, I put liquid nails on the back and then using screws and fender washers I put them up in between the ribs.

Edit: I used 2.5 inch screws. The fender washers hold the screw head out a bit, but there is just enough length to suck the foam panel up tight without going through the floor. I think my floor is 5/8ths.





So far I have put the four main panels in. I will be measuring the odd sized sections and doing them as the weather around here allows. Once all the panels are in I will be going around the edges etc with Great Stuff.

It will be interesting to see how well it holds up. But if there are problems then I can always just do plan B.... cover the bottom with the fiberglass reinforced panels.

I just discovered this gem of a thread. Nice work Cindy. I'm halfway into an epic conversion process myself. Eventually I'll get around to posting a build thread. But for now a question about underside insulation to those of you who have done it: Do you worry about moisture accumulation between the wood floor and the insulation? I realize that SW Idaho is slightly drier than my climate in Spokane, but I know you do get some rain. I would love to cover my underside with some blue or pink foam. But I'm afraid that when I drive in the rain, moisture would seep under the foam and cause corrosion and rot. Thoughts?

[Rainier70]

Mike, all I can really say is that I just don't know. We are so much drier that I haven't really worried about water staying in contact with the wood.

If I still lived on the coast......First I would do a good job of sealing the bottom wood and rails before I added any insulation. Then I would glue and screw my insulation up and seal the edges. I think it might be good for your piece of mind to at least leave one or more pieces not glued up. Then after a particularly wet trip, you could take that piece off and check conditions under it.

Best answer maybe to put a layer of frp or coroplast across the underside and seal it up.

Good luck and let us know how it works.

[lrrowe]

This is just a wild thought that just came to me. How about leaving an air space (maybe 1/4" or so) between the foam and the underside of the floor. Then if there was a weep hole there, maybe any moisture that did get in, has a way out. Again I have not taken the effort to consider all the pros and cons.

[Mike S]

This is just a wild thought that just came to me. How about leaving an air space (maybe 1/4" or so) between the foam and the underside of the floor. Then if there was a weep hole there, maybe any moisture that did get in, has a way out. Again I have not taken the effort to consider all the pros and cons.

That's an interesting idea Bob. Having extra air space that isn't sealed would defeat the purpose of insulation. However, if were easy to seal up, it might work. Your comment gave me and idea: create a 1 inch air space using 1x1 wood strips on the underside of the trailers floor. Then attach the foam to the strips. Then seal it up as well as possible. Is that worth the trouble? I don't know. I'll think about that for a bit.

[Mike S]

Mike, all I can really say is that I just don't know. We are so much drier that I haven't really worried about water staying in contact with the wood.

If I still lived on the coast......First I would do a good job of sealing the bottom wood and rails before I added any insulation. Then I would glue and screw my insulation up and seal the edges. I think it might be good for your piece of mind to at least leave one or more pieces not glued up. Then after a particularly wet trip, you could take that piece off and check conditions under it.

Best answer maybe to put a layer of frp or coroplast across the underside and seal it up.

Good luck and let us know how it works.

Thanks Cindy. I'm in the process of sealing up my wood and rails now. I'll re-evaluate the idea once I get that done. I also have a layer of 1 inch foam under my sub-floor. I might see how that does for the winter.

[lrrowe]

This is just a wild thought that just came to me. How about leaving an air space (maybe 1/4" or so) between the foam and the underside of the floor. Then if there was a weep hole there, maybe any moisture that did get in, has a way out. Again I have not taken the effort to consider all the pros and cons.

That's an interesting idea Bob. Having extra air space that isn't sealed would defeat the purpose of insulation. However, if were easy to seal up, it might work. Your comment gave me and idea: create a 1 inch air space using 1x1 wood strips on the underside of the trailers floor. Then attach the foam to the strips. Then seal it up as well as possible. Is that worth the trouble? I don't know. I'll think about that for a bit.

Wood strips is what I was thinking. And does not the air space, if sealed, create a form of insulation itself. Maybe a expert could comment on that.

[rebapuck]

You could create an air space by installing that construction mesh they use under wood shingles.

[Rainier70]

The wind is blowing like crazy here, but it is only about 30 degrees, that is an amazing combination for us. Usually when it is blowing like this in the winter it is too cold to mess around outside. So with the "balmy" weather I ran out to my ct and decided to do an acid test burn with the Nuway propane stove and my modified vent cap. I know that most of you have seen the changes I made, but since some may not have I will detail them again here.

The wind is pretty steady at about 30 mph with gusts up into the 40s. It nearly blew me off of our side porch. I ran the stove once before in a wind close to this, but I got to thinking that maybe the direction the wind was coming from might make a difference.

This is the 3 inch vent cap that I got from HD. http://www.homedepot.com/p/Master-Flow- ... /100396969



My stove pipe comes up about 4.5 ft before exiting out the side of my trailer. At first I tried to just run it with the unmodified cap right out the side. That was okay with no wind, but when the wind came up I was getting exhaust in my door when I would open it, and the wind would blow the stove out. Next I tried extending the pipe outside the ct to above the roof. No exhaust in my door, and it was better in the wind but still would occasionally flicker or blow out. I even tried a different "high wind" cap. It didn't fit well.

Finally I thought to modify the cap I had. I brought the exhaust point back down a horizontal ending on the side of the ct, but now I used aluminum tape to block the two vent ports on the sides, leaving the top and bottom ones open.



It worked beautifully! With the side vents blocked the exhaust goes straight up and the flame isn't bothered by the winds I have encountered so far. Unmodified the side vents on the cap were scooping the wind in. With them taped shut the wind can't come in the sides.

Now for today's test. If it can burn okay in this wind, it will be okay in just about anything.



Score!! Nary a flicker. The wind isn't bothering the flame at all.

[AZ_Desert_Rat]

Great Job Cindy and thanks for the ideas and documentation of your tests
How has the under-floor foam been working for you so far ... I am considering doing something similar in my CT ??

Make sure to take some pics of that next trip

[Rainier70]

Great Job Cindy and thanks for the ideas and documentation of your tests
How has the under-floor foam been working for you so far ... I am considering doing something similar in my CT ??

Make sure to take some pics of that next trip

On the under-floor foam: Since I put it in I have traveled abt 2500 miles. At least 500 miles of that was on gravel roads. I camped for weeks at a time from April to December. At the end of the season I looked under the trailer for wear and tear. The canvas/glue/paint covered foam pieces show no wear at all that I can see. I left one small piece of foam bare. It is located just behind the front lip of the trailer. It is 2 or 3 ft long by about 14 inches wide. It shows some small nicks and dints from gravel hitting it, but really very little damage at all. I still need to finish filling in the odd corners and do some foaming with the spray cans, but even without that finish work, it made an unbelievable difference in the warmth of the ct. It also cut the amount of fuel I was using.

In the high mountains of Idaho, Utah, Wyo etc where I camp, cold nights and winds are the norm. It frequently freezes and most morning at least I will run my stove to take the chill off. Before I insulated the floor, when the wind would blow it really sucked the heat out. Now the ct stays a much more even temperature. Less gain in the heat of the day and stays warmer through the night. Now I seldom run the heater all night.

If I was to do it again, then, yes, I would definitely insulate the floor. But I would probably just use the 2 inch pink or blue form without anything over it. On second thought I would probably paint over it. I am not sure if reflected uv will damage the uncovered foam over time. If you think that there is too much road damage over time, then you could always add a cover of frp or coloplast over it later.

[Rainier70]

This is a quote from further back in my build, but it shows how the uncovered insulation fairs. My piece of uncovered insulation has more dings now, but not enough wear to worry about.

A preliminary verdict on the bottom insulation.

So far since putting my under frame insulation in I have travel well over 100 miles on gravel roads and about 300 miles on paved. I am seeing nothing but a little dust on the canvas covered insulation. I also have three small sections in the front of my ct that have mostly uncovered pink foam insulation. It shows a little dust and maybe a couple of little tiny rock dents. No real wear at all.

I private messaged BC Dave about his insulation also. He glued on his insulation with no covering. He hasn't traveled as much with it, but it is holding up fine and shows no damage.

Then I saw this post by Nobody. He has had uncovered insulation on the bottom of his camper since 2006, and had it on all kinds of roads.

There probably as many answers to your question as there are builders on this forum. None are 'wrong' or incorrect. What's right for one person may not work as well for another.

I built my TD in 2006, using an HF 1800# trailer & a couple of profile drawings I expanded from quarter inch graph paper. I built my floor from ripped spruce 2x4's, 1x6 pine for side rails, & 1/2" CDX ply for the decking. After the 'floor' was completed I inverted it on a couple of sawhorses & 'painted' it with asphalt roofing compound. Contrary to conventional wisdom, the coating wasn't nearly as 'stinky' as expected, & the 'tackiness' only lasted as long as it took to dry (overnight). I then cut pieces of 1" styrofoam (Dow 'blueboard') to fit the recesses under the floor, installed them with PL Adhesive, & as an extra caution, I used small pieces of scrap wood as 'battens', 'nailed' to the floor frame with 18ga brads from my HF nailer/stapler. Almost 8yrs & 20K plus miles later (towed thru all kinds of terrain from freeway to National Forest/BLM back country roads/trails) the foam shows considerable stains/marks of travel, a few tiny 'gouges' probably from road debris, but NO deterioration or tendency to 'de-laminate' from the floor. In SE New Mexico in 2010 we encountered standing water in the streets of several towns, that in places almost 'floated' the TD. I've also driven through lots of heavy rain/T'Storms where I'm sure the tires & passing vehicles sprayed lots of water up under the TD. I've found no indication of residual moisture nor any evidence of rot in the wood portion of the floor, nor corrosion to the metal of the trailer chassis. As an aside, I live in central Arkansas where our average humidity is quite high & equipment not properly protected has ample opportunity to suffer ill effects from it...

Here's a few pix of my floor under construction





This how the underside looks this morning (not bad considering what it's been exposed to since 9/2006)

I think we have been over thinking and over engineering floor insulation. I don't regret covering my insulation with the canvas/paint coat, but after having seen how my uncovered insulation is holding up and how little "wear" others have experienced, I think it will be more than adequate for the long haul. I am wondering if the "cover the insulation" comes from RVs and trailer houses originally using fiberglass batts that needed protection from water etc?????

I will continue to check on mine on how it is doing, but I won't be canvasing over the small odd shaped pieces of exposed foam that are in the front. I will be doing some foam fill in spots that I haven't gotten to yet, but that is about it.

In short, if I was to do it again I would glue and screw the insulation on, or batten it, but I wouldn't worry about putting a cover over it. You could always do that later on if you wanted.

[abqlloyd]

I'm using Tyvek house wrap under mine. It's what they use on high-end RV's and a small roll is cheap.

[Rainier70]

That should work great..... Water resistant and breathable.

[professorkx]

I'm using Tyvek house wrap under mine. It's what they use on high-end RV's and a small roll is cheap.

Can you share where you have found small rolls? The rolls I am finding online are 150 foot long, and almost $100...

Thanks