Complete Sub Floor Replacement :O

[BigBlueSkyAvion]

Hey there! Ive got a 1964 T20 Sportsman Avion. There are 4 patches of rot around the edge of the subfloor and I wanted to just replace the whole thing. NOW, I'm wondering what I got myself into?! Keeping the outer skin stable and secure to the trailer bed is my worry. There are rivets and vintage trailer screws attaching the current sub floor to the skin and bolts attaching the floor to the bed.
Removing and replacing all the screws and hard to remove (without drilling too much or in an area I wouldn't want to) rivets seems like a risky move. Shall I keep what ever non rotted subfloor attached as is and try to attach that to the new subfloor to go for the complete removal??? OR something else

[silverloaf]

BBSA -

I have replaced several complete sections of floor in our trailer. It also includes steel underneath. I'm sure there are others in the forum who have tackled the entire floor. I hope you get lots of feedback besides me, especially with the earlier models like yours.

Before pulling out the chainsaw and jackhammer, I recommend you go to school on the anatomy and skeleton of your particular trailer. This includes locating all the steel cross-members that picture-frame and run cross-ways under the floor. These are the load points that support the floor assembly. Envision being able to see the plan and cross-sectional views of your trailer. You will learn the edges of the floor conform to the curve of the outside skin; in ours, it was 12 degrees at the floor line and 6 degrees further up the wall.

In our trailer, the floor was constructed as a sandwich (plywood-foam board-plywood) off-trailer and shuttled onto the chassis. The "vintage" bolts you refer to are likely elevator bolts. They secure the floor assembly to the cross-members. I cut mine out with a small angle grinder. The bolts are still widely used today in many applications..

There are other screws that secure the wall assemblies to the floor assembly. They are run though the c-channel beneath each wall. There are not many bolts and screws used as one might imagine.

The aluminum hull is remarkably strong and stiff. In our trailer, it's a combination of the framework, the riveted outside skin and close-cell, spray-foam insulation. It maintained its integrity when I replaced a large section of floor in the rear.

By removing small portions of old floor under the wall, I inserted 2-1/4" shims (the thickness of the floor) between the bottom of the c-channel and a cross-member. I moved these shims around as I inserted new segments of floor assembly. I always made sure a floor joint was beneath a steel cross-member (or floor support), using a 2x2 spline to interlock each floor segment together.

Remember, my explanation is for our trailer, not yours. It took me a long time to figure out the mechanics and steps to do this, well before joining this form. You will find lots of help here.

[Sawmiller]

A complete floor replacement can be done, but it's quite a job. Removed and replaced my entire floor on my 1968. Removed all interior cabinets, bathroom etc. Removed the floor and jacked the shell up with two t posts in the center of the trailer. Then I re installed the 3 layer floor with solid wood around the perimeter. The perimeter solid wood had a tongue cut in it to accept the upper and lower layer of plywood. After the layered floor was in, I put aluminum angle iron around the perimeter of the Avion and secured it to the walls and floor.

[silverloaf]

A complete floor replacement can be done, but it's quite a job. Removed and replaced my entire floor on my 1968. Removed all interior cabinets, bathroom etc. Removed the floor and jacked the shell up with two t posts in the center of the trailer. Then I re installed the 3 layer floor with solid wood around the perimeter. The perimeter solid wood had a tongue cut in it to accept the upper and lower layer of plywood. After the layered floor was in, I put aluminum angle iron around the perimeter of the Avion and secured it to the walls and floor.

Very nice rebuild and thought process! I almost think its more difficult trying to graft in sections than replace the entire floor.

My biggest problem was finding space to store all of the cabinets, bed frames, couch, walls sections, etc.


Had I owned a barn rather than retro ours on a patch of driveway in our backyard...….

[brian.christopher]

I moved most of mine under a tarp thinking it’d be a couple days, that was six months ago now I have a trailer full of mulch stuck to laminate.