Teardrops n Tiny Travel Trailers

Ok, well I went and made a mistake on my build and my build is at a dead standstill. Put both of my skins on one of my walls (the passenger wall with the door) and realized I forgot to insulate

I'm left with a couple options due to the fact I also glued my skins into place and they will NOT come loose. I am doing a 1/4' ply / 1x2 pine / 1/4" ply construction, the wall cavities are 3/4" deep and 12" wide. The interior and exterior will be natural wood and not painted or covered up. I also want the insulation for the option of camping in cold weather and/or air conditioning the interior.

1. Leave the wall alone and insulate the rest of my build
2. Try to find a way to force insulation into the wall
3. Rebuild the wall from scratch

I have considered the following for option two and don't like any of them.

• Spray Foam - Afraid the expanding type will bow the walls. The Non expanding type, which i already purchased a can of it to test out, looks like shaving cream when it comes out and will take a TON of it to fill the voids.
• Fiberglass Insualtion - Spend days pushing it into a little hole in the framing
• Polystrene Loose Fill - Find a way to poke this bean bag material into a hole in the framing

The big question is has anyone not insulated a sandwich construction wall and camped in hot or cold weather? Also has anyone else done this and came up with a better construction option for insulation. Not a huge setback, but really don't wanna buy four more pieces of 5x5 baltic ply and reframe the wall if someone else has a solution.

I wouldn't use foam spray. That's a recipe for disaster! if it were me I'd continue and just make sure the rest is well insulated. A/c shouldn't be a problem as it's a small space and a 5,ooo btu, IMO is overkill anyway. And heat.... Well, it all depends on how you plan on heating it and how cold you plan on camping in it. good luck with your decision . So, were you distracted by your helper?

Right now....yeah...foam isn't the way to go, a hassle and could be "puffy" walls. So just how much cold weather camping are you planning on? I have no insulation on 3/4" walls, except the ceiling and been in mid 20's in snow and had no real problem.

You've decided on your options, at this point...how bad do you want it insulated?

Me...I think your best bet if it's just gotta be insulated, rout out the panels, insulate it with sheet foam, re-cover and take it as a lesson learned. It's probably the only way to really give you peace of mind that it is completely insulated. The other methods will always leave you with some doubt. I'd leave it. The air cushion will give you "some" insulation. Just me though. Doug

Routing out the cavities isn't something I even thought of, good idea. Gonna sleep on it and decide in the morning. Leaning towards just leaving the wall alone, 1/3 of the wall is door, which I can still insulate, so 2/3 without insulation I don't think will be a huge loss.

Just tabbed out during typing this and looked up the R value math. Both sheets of ply added together have an R value of .75. The air space has an R value of 1 for a total of 1.75. Changing air to Polystyrene adds a R value of 3 for a total of 4.75 with the insulation.

Heat Loss = (1/R value) x Surface Area x Temperature Variance

So this equals 1285 btu per hour lost with leaving it air gap in 20 degree weather while maintaining a 70 degree inside temp. Using the same figures with Insulation heat loss is 473 btu per hour. This would be the extreme conditions which I wouldn't even do very often at all. Higher outside temperatures would minimize this loss even more.

The heater I would intend on using in the above conditions would be adjustable between 4000-9000 btu selectable which will WAY outperform the heat loss. Not to mention the cabin will be vented anyways to avoid suffocation.

So end result after factoring all of this is I'm leaving it alone and moving on. Should have just considered the math before even stopping the project for this thread. Back to construction in the morning

The math for heat loss was interesting to me though, so not completely wasted plus someone else may want to find heat loss at some point.

R values are great things to know, but till you spend a couple of nights in one in a variety of temps, you won't know for sure. I'll bet you'll be fine...too much math makes my head hurt.....Doug

Moho,
Check out 2 part boat flotation foam. As long as you have one direction for it to expand, it won't cause a problem. See the video, poured into a cup it expands out of the cup, but doesn't damage the cup. Exit holes would also help control expansion.

http://www.jamestowndistributors.com/userportal/document.do?docId=805&title=Tips+for+using+2+Part+Urethane+Foam+


Larry C

If you can still get to the top of the sidewalls(where it will be covered in the end) perlite can be poured through a fairly small hole( I have used 3/4"but 1/2" would probably work) into the wall cavities. We did this to an old plaster/lath clapboard sided house where the owner didn't want a bunch of big holes to be repaired. We used a steel funnel, poured good with no static cling, but if there is a hole, THE PERLITE WILL FIND IT'S WAY OUT!

http://www.perlite.net/

Could you use a router to remove the inner skin by cutting between the frame timbers. If your walls are mirror image, you have the other wall as a guide.
You could then add the insulation board you require and reskin. You would just lose 1/4" internal width, as you've effectively "shimmed out" your inner wall by 1/4".

Are you going to run any wiring in the walls? If not I would leave it alone. If I need to put wiring in, I'd go with Mallymal idea.

Yer dimentions are questionable...Maybe "I" read it wrong.. 1/4 ply 1x2 pine 1/4 ply

My calculations put yer walls at 1inch and 1/2 THICK .. ?? Izzat correct ?

Next.. you don't mention HOW cold you plan to be campin in .

Do the walls have "pockets" to recieve the insulation or are they SOLID ?

My little guy has been "rebuilt" by me.. the roof has been insulated as has the front/back radii...as has the hatch.

I live in So.Cal. but have been down into the 30s in the rain and STILL had to open the vents to "cool off" the interior.

Of course, mine is a 4 wide and body heat is a wonderful thing ! ( I camp alone and am of small stature 160lbs)

IF yer sides are 1& 1/2 inch thick...that should be sufficient !

Jus my 2 cents

canned o minimum ,, keep in mind that a 1x2 pine is actually 3/4 x 1 1/2 inches a 2x4 is really 1 1/2 x 3 1/2 inches an so on an so with other lumber . Thus his measurements are correct.

The other option would be to chisel off one layer of ply and only replace the one torn up sheet. Routing out and adding another sheet of ply will leave you 1/4" wider on one side. it doesnt sound like much but when you skin the roof all your material will be short. frustrating isnt it. good luck DR

Unless you made the interior 1/4" less....depending on how it's exterior is finished off IE with aluminum....1/4" split between 2 sides can be taken care of under trim cap with butyl tape.

I bet it's way too late.... but router down from top interior edge apx 2 1/2 " and using a rod to poke the walls full of blown type or fiberglass insulation. Cover the oops area with a trim board. OR.... just leave it alone.

Mike