Ceiling Insulation Question

[phoenixbound]

I am in the process of insulating my trailer. I am using 1" Styrofoam on the walls. There is 1" of space so it's perfect. Checking the ceiling I noticed there is 1 & 1/2 '" of space. I don't know whether to go ahead and use the 1" and leave an air gap or get 1 & 1/2" insulation. The air gap helps with insulation, right? Could be slightly tougher to install. The space is right at 1 & 1/2". Thank you.

[John61CT]

Actually ceiling is more important, then wall, floor least.

Go 1.5

[CoventryKid]

I added insulation between the ribs in the ceiling then strapped 3" wide strips of 5/8" plywood to each rib down the length of the trailer. Kept the insulation in place and also provided space to run 12v electrical wires, mount LED lights, etc. Screw your finished ceiling material to the plywood strips, not the metal ribs (thermal break). Pictures are in my build link (below).

Also, some members have used Henry's roof coating (https://us.henry.com/roofing/reflective-coatings/white-roof-coatings) on the roof to reduce the amount of heat generated on a sunny day. I haven't done this (yet).

Hope this helps.

[McDave]

Air gaps can be useful, but.... They only help if executed properly. "Dead air" is an effective insulator but its not easy to achieve. The air gap must be air tight or else it is just a leak. The odds are probably better with more poly iso. The foil faced (both sides) is about R-6 or 7 for 1". 1.5" should get you close to R-10. That is still not a lot but it makes a big difference. Like the "Kid" mentioned earlier, Henry 587 roof coating will also be a huge help for you. Arizona has about 300 days of sunshine per year so heat will likely be your biggest issue. The Henry 587 is a reflective coating and it really works to lower roof temp. by reflecting the sun's rays, not absorbing all that energy. 1 gal. did my 6 x 12. Probably the best $35.00 investment I have made. Easy to apply, takes a morning. These trailers were not built to accommodate a lot of insulation so whatever else you can use to control temps is a help.

McDave

[hankaye]

Howdy All;

Unless you camp where it never rains you want insulation up top. Why am I equating it to
rain??? Imagine living inside a drum ... Noticed this quality when I camped in my brandy new
CT under a fir tree just after a gentle rain. The drops that dripped from the tree where
larger and it was like listening to Maggie O'Sullivan's tap dance class for Hobbit 3 year-olds
dancin' on the roof.

hank

[onehoser]

Howdy All;

Unless you camp where it never rains you want insulation up top. Why am I equating it to
rain??? Imagine living inside a drum ... Noticed this quality when I camped in my brandy new
CT under a fir tree just after a gentle rain. The drops that dripped from the tree where
larger and it was like listening to Maggie O'Sullivan's tap dance class for Hobbit 3 year-olds
dancin' on the roof.

hank

the wind blowing over the sheet metal at night is a real treat too

[fourbtgait]

I always liked the sound of waking up to rain on a corragated tin roof. It meant I didnt have to get up right away and go to work.
As stated, I put Henrys on top for reflective and fully seal, 1.5” polyiso with ceiling attached to wood strips, but only 3/4” wide.