Is it safe to assume interior walls aren't load-bearing in a single-wide?

In a 1989 single-wide, you’re almost 100% safe to pull that wall. These units were designed so the roof trusses span the entire width from one exterior wall to the other. Those interior dividers are basically just curtain walls for privacy and don't provide any structural integrity to the roof system. If they were load-bearing, the manufacturer would have had to reinforce the chassis specifically to handle those point loads during transport, which they almost never did for standard models.

You can verify this by popping off a piece of the wallboard or the top trim. If you find **1x3 studs** or thin 2x2s, it's definitely not holding anything up. Even if they used 2x3s, they usually feel bouncy or have a bit of give if you knock on them because they aren't compressed under a load. Real load-bearing walls in manufactured homes are usually only found in double-wides where the two halves join at the marriage line. The biggest headache won't be the structure, but the cosmetics. When that wall comes down, you’ll have a gap in the ceiling panels and the subfloor. The ceiling material under that wall is going to be a much brighter white than the rest of the room because it hasn't been exposed to dust or light for decades. You'll probably want to patch the gap and then hit the whole ceiling with an airless sprayer to make it look like one continuous room. Since you're doing this for a power chair, keep the floor transition in mind. You’ll want a completley flush surface so she doesn't get hung up moving between the bedroom and bathroom zones. Removing the wall is a smart move because even if you widened the door, the hallway turn in those old single-wides is usually too tight for a heavy chair to maneuver. Opening it into a suite is the only way to give her the turn radius she needs.

Since you're pulling that wall to make room for a heavy power chair, you're going to want to reinforce the subfloor while you've got it exposed. Those 1980s mobile home floors are notoriously soft. I always use Advantech subflooring panels for these jobs because they handle the weight of a heavy wheelchair without sagging or warping like standard OSB. It'll give her a way more stable surface once that divider is gone. If you're patching the gap, just swap the whole section out for Advantech and she'll be set for years.

I did this exact layout change on an '87 and the wall came out fine, but watch out for the plumbing vent stack. usally, there's a PVC pipe for the bathroom sink or toilet running right up thru that wall to the roof. I had to reroute mine into the exterior wall beacuse I didn't want a random pipe in the middle of the new suite. It’s an extra day of work if it’s there. Also, check for those thin metal straps they sometimes use to tie the roof to the floor during shipping. If you see one, just screw it into the nearest exterior stud before you cut it out so the roof stays tied down.

Spot on about the trusses. I've gutted a few of these and never seen a load-bearing interior wall in a single-wide. One thing to look out for though is the ceiling batten strips. ussually, the wall is tucked right against a seam where two ceiling panels meet. When you pull the top plate, you're going to find that the factory didn't finish the edges of those panels behind the wall. You'll probly need to pick up some matching vinyl-wrapped batten strips to hide the new seam, otherwise, it looks like a jagged mess even if you patch the holes.

Check for light switches before you start swingin' the hammer. Usually that wall's got the bath switch and maybe an outlet. Since she’s in a power chair, you shold move 'em lower anyway—standard height's way too high for someone seated. I’d drop 'em to about 36 inches while you’re alredy messin’ with the wires. Also, wear a mask. That old wallboard and insulation dust is nasty and gets everywhere.