Ceiling insulation and spar pics needed, please...

[Robin Bobula]

We are just about to start insulating the ceiling of our Horton 7x18 V-nose trailer. Being a newbie at this, with almost no construction background, there are a few things I haven't been able to figure out from the various posts on the subject.

There is not much space between the metal roof and the tops of the metal beams of the ceiling. Should I try to cram a thin layer of something between the roof and the metal frame, or just insulate between the framing pieces? My plan was to use some Reflectix first, and then a layer of the styrofoam cut to fit tightly between the metal framing. Being a little OCD, I thought if I trimmed the Reflectix so that only a layer of foil remained at the edges, those thinned edges could fit between the roof and the framing. Don't know if that would be a waste of time or not.

Also, folks talk about putting wood spars on the ceiling to which to attach the ceiling material. This makes sense to avoid having ceiling screws directly into the metal frame which could lead to condensation. How exactly does one put in ceiling spars and how do you attach them to the framing? Would I do this before or after insulating? I don't want to lose too much height in the trailer. Any pics you have would be greatly appreciated. Thanks!!

Robin

[toypusher]

I am not sure about the insulation - especially without actually seeing what is there, etc.

HOWEVER! You might consider running any wiring that you will need before closing that are up.

[notoriouskelly]

I used 3/4" foam board for ceiling ($3.38 2'x4' at Home Depot) and Reflectix insulation perpendicular to it.

Used 1" foam board in walls ($3.68 Home Depot)



Foam can be wedged in most places; Reflectix I used double-sticky duct tape to hold in place until panel installed.
Liquid Nails etc wasn't holding too well- next time I'll just use the tape.

Current paneling is solely for retaining insulation during road trip; I'll probably put white plastic sheets up later.

When trailer skin is too hot to touch, the spars were only lukewarm so I didn't sweat them too much for that reason.

Have fun!

[lmajeff1]

Hello Robin,

If you look at the gallery of my trailer you will see how I insulated my CT.

Jeff

[Robin Bobula]

Thanks, Jeff, I'll have a look!

Robin

[Pyrofish]

I don't think I have a good pic of my ceiling. You can sort of see the wood that holds up the insulation and will be the attachment point for whatever material I use for the ceiling in this pic.


I wouldn't worry about the space between the frame and the roof. Just shove the insulation up there between the existing metal. I live in Florida with lots of sun, so I screwed a 1" aluminum box tube to each roof spar. That gave me 2" depth from the roof to the bottom of the structure and allowed me to use the 2" foam. If I lived somewhere not quite as hot, I'd have stayed with 1".

For the wood, I went to Lowes and asked them to cut a sheet of 1/2" plywood into 3" strips. I screwed that to the roof structure, running lengthwise in the trailer. The reason I went lengthwise, as I'd have preferred to go crosswise, was the spacing between my roof structure was so wide, I wanted more support up there then just screws down the edge and one row down the middle. Running the boards longways, allows me to put in row screws where they are needed. It's also a PITA, and perhaps a little over thought.... Oh well, it works.

[Robin Bobula]

Thanks, Pyrofish! You're right about trying to fit insulation between the roof framing and the roof skin -- there was some minimal foam like material adhered up there, so I just shoved the edges of the Reflectix under as much as possible so the roof framing holds it up. I started adding 3/4" sheet foam insulation under that, so that the bottom of the foam is level with the bottoms of the framing. The foam will support the Reflectix if/when it sags down, and any sagging will provide the air space needed for the Reflectix to work optimally. I hope.

I love your idea about the plywood cut into strips, and will probably steal it.

I was planning to insulate between the plywood spars with an extra 1/2 inch foam, laid lengthwise, so that the spars and foam create a level surface against which to put the ceiling material (as yet undecided). My husband doesn't think the extra 1/2" will be needed. I'm thinking the extra won't hurt. We live in PA, where the weather can vary a lot.

Thanks!
Robin

[lmajeff1]

Hello Robin,

You would be suprised how much that extra half inch will help

Jeff

[OverTheTopCargoTrailer]

If you want really first class insulation job - you really need to keep any of the CT skin from touching the metal ribs .....
for example VHB tape from 3M as the trailer is being built....

then you need to build a 2nd box inside your CT

as your insulating a CT and not a house ....the metal ribs transfer HEAT or COLD ......
just like wires inside a toaster oven....

The distance of insulation from the interior face of the metal studs / ribs to the finished surface gives you your R value.....
Heat always travels the path of least resistance....
ie if you have R50 walls and only a plywood floor ....it will still get hot or cold as hell...depending on the exterior temp.

if you want the CT to go to Alaska & Nevada then build it like that.....like a refrigerator car
if your only gonna hang out where its 50-75 deg ...then don't waste your time insulating

Generally - however the CT will be about 4 -10+ deg more on the interior then the exterior temp ......
It changes very fast with the exterior temperature & or sun / shade
so you need to add that much heating or cooling to make it in your preferred range...


http://overthetopcargotrailer.blogspot.com/

[pete42]

I think adding insulation to the cargo trailer is a good idea no matter where you live.
not that costly to do money well spent I think.

pete