Insulate the floor or no?

[kludge]

Even though I insulated my floor - it wasn't much work to do so - I also used 1/2" foam exercise matts on top of the floor too.

That's a cool idea. I'm also giving Bob Henry's sheet on insulation under the floor some thought. Any pictures of that???

In Indiana in the the spring and fall 30-40 degree temperature swings are not uncommon. Humidity ranges from 30% to 100%, although the extreme heat and dryness of this past summer was the most uncommon one I've lived through... and I've been here a looong time. Heavy dew can be like 1/10th of an inch of precipitation. And though it's not THAT cold, there's usually a week or two in January when it gets down below 10 deg or lower and just stays there. It usually coincides with the Winter Camporee.

[Nobody]

Lotsa answers here (& they're all valid) so you can do as you choose. After all, it's your build, do as you wish. I've never heard anyone (or heard OF anyone) who regretted insulating. It's usually inexpensive, doesn't take much extra time, & generally pays dividends in more stable temps and/or less condensation. I built my floor 'off the chassis' so it was easy to coat the bottom side with asphalt water proofing, & insulate with 1" foam board (or perhaps it was 3/4" ) while inverted, then just 'flip' it right side up for installation on the trailer. I cut the foam board pieces to be a 'tight fit', used very little construction adhesive, then used scrap strips of wood as 'battens' stapled against the foam to insure it stayed in place. We've towed our TD 16K+ miles since 2006, over every kind of road/terrain from freeway driving to forest trails that are only 2 tracks with heavy vegetation growth between the tracks. Even drove thru 12+ inches of standing water in streets of several towns in SE New Mexico couple of years back. The foam board still looks near pristine & hasn't moved at all thru all this exposure to various extremes. If you have the opportunity to insulate with little extra expense or effort, I'd recommend it



As evidenced by this pic from when I was 'rear-ended' Labor Day weekend 2010, the under floor insulation shows little to no damage or wear from road debris or other causes...