Velit VE49QV Roof Thickness Requirements and T@B Trailer Installation Guide

Updated 04/21/2026 | Published 04/11/2026

Question:

What range of roof/ceiling thickness is required? I’m Installing it in a T@B trailer and will be reinforcing the roof in that area.

asked by: Rick

Expert Reply:

Hi Rick,

Great question, and you’re right to want to make sure this lines up.

For the Velit unit part # VE49QV, the required roof thickness range is 1.99 inches to 3.54 inches, so that’s the range you’ll want to be within for proper fit and sealing. The good news is that a typical T@B trailer roof is usually built within that range. They generally have a lightweight, arched aluminum or composite outer skin that’s about 1/8 inch to 1/4 inch thick, supported by a structure that brings the total roof assembly to roughly 2 to 4 inches once you factor in insulation and the interior ceiling.

Because of that, if your roof is already within that thickness range, you likely won’t need to build it up just to meet the spec. Where you may still need to make a small adjustment is the mounting surface itself. Since the T@B roof is curved and designed to be lightweight, you’ll want to make sure the area where the unit sits is flat and well supported so the gasket can seal evenly and the unit isn’t sitting on a curve or flexing over time.

As for the opening, this unit is designed to work with a 14 x 14 standard roof cutout, so in many cases you can reuse an existing vent opening. That’s often the easiest approach.

Do you have a vent on the T@B currently?

expert reply by: Heather A

David

4/17/2026

I installed the Velit mini in my camper van last summer. It was a replacement so the hole in the roof was already cut. Additionally I had to work around ann existing roof rack, roof decking, furring strips and tongue and groove ceiling. It was the only DC A/C unit that fit the space. With ceiling and furring strips there was plenty of thickness. The 2 main challenges were the anchor angle brackets and fishing the large electrical connector. The anchors work well, however I had to orient differently to accommodate the existing ribs and furring strips so had to create a new way to secure the cowling. The electrical connection was in an awkward spot for my existing configuration so had to orient the anchors to leave space. I’m happy with the result. It’s solidly anchored and has survived many trips. Wonderful A/C system. Works perfect for us.

Heather A.

4/21/2026

@David That’s an awesome real-world install, David really appreciate you sharing those details. t sounds like you did a great job adapting the Velit to your setup, especially working around the roof rack and interior structure. Those anchor brackets can definitely be one of the trickier parts of the install. Glad to hear it’s held up well through trips too. That’s always the big test, and it sounds like you’ve got it mounted solid. What kind of camper van do you have?

David

4/21/2026

@HeatherA I have a Ford Transit 250, LWB. Original buildout was by a past owner through Tommy Camper Vans. I was replacing the Fresair evaporative cooler, which works great in the desert SW but not in Florida. My wife and I have enjoyed modifying the layout, etc to fit our needs.

Heather A.

4/21/2026

That makes a lot of sense, David, Florida humidity will definitely push you toward A/C over an evaporative setup. Also really cool that you and your wife have been able to make the space your own. Are you guys mostly staying local in Florida now or still getting out on longer trips with it?

See All (5) Replies to David ∨

Rick

4/18/2026

Yes, I'm removing the vent/fan now. It looks like the thickness is only about 1-1/4" but that will work fine as I'll be adding another 3/4" to help support the roof.

Heather A.

4/21/2026

@Rick Nice, that actually sounds like a solid plan, Rick. If you’re currently at about 1-1/4" and adding another 3/4", that’ll put you right around 2", which lands perfectly at the bottom end of the Velit’s required range. That’s exactly where you want to be for proper clamp pressure and a good seal. Sounds like you’re on the right track, this should come together really nicely. Let me know if you need anything else!