9.7 Meter Triple Axle 1979 Avion Floor Rebuilding

[Pneuma1]

Thank you Silverloaf. Going to definitely buy one now that I know. My hands, hair, eyes, nose, muscles and lifetime thanks you

[Lagniatte]

Is there any reasoning behind leaving the legacy insulation in-place? I am at a similar stage with my 34' and found the insulation is in pretty good shape, and the old hard insulation seems to add to the rigidity of the walls. I am debating whether ripping everything out (old wiring and insulation), or leaving the old insulation in place and trimming the old dead wire to leave in the walls. If I leave the old insulation in place, I will need to cut channels in the insulation for the new wiring. Thoughts?

[silverloaf]

I had an insulation business as my 2nd career. We sprayed a lot of foam insulation. The wall and ceiling cavities in your trailer (and mine) were sprayed with 2-part, closed cell, low expansion polyurethane foam. It provided the greatest R-value per inch and added structural stiffness for the side walls and ceiling.

I recommend not removing the foam. It will be extremely difficult to make it level for the interior skin. Yes, you can cut a trench in the foam to replace or add wiring. I suggest using an oscillating saw to cut the slots surgically.

Once complete, purchase a product similar to the ones on the website below:
https://www.touch-n-seal.com/foam-sealants.html

I like the All-Season Foam for filling gaps, gaps and trenches mentioned above. It cures fully in about 20 minutes. It can be trimmed with the oscillating saw.

You will need to purchase an applicator gun and some cans of spray cleaner. I have a contact where you can purchase products on-line. Let me know if this is the route you want to take.

[Lagniatte]

I had an insulation business as my 2nd career. We sprayed a lot of foam insulation. The wall and ceiling cavities in your trailer (and mine) were sprayed with 2-part, closed cell, low expansion polyurethane foam. It provided the greatest R-value per inch and added structural stiffness for the side walls and ceiling.

I recommend not removing the foam. It will be extremely difficult to make it level for the interior skin. Yes, you can cut a trench in the foam to replace or add wiring. I suggest using an oscillating saw to cut the slots surgically.

Once complete, purchase a product similar to the ones on the website below:
https://www.touch-n-seal.com/foam-sealants.html

I like the All-Season Foam for filling gaps, gaps and trenches mentioned above. It cures fully in about 20 minutes. It can be trimmed with the oscillating saw.

You will need to purchase an applicator gun and some cans of spray cleaner. I have a contact where you can purchase products on-line. Let me know if this is the route you want to take.

Thanks, Silverloaf. I plan to leave the insulation in place and cut in new wiring as needed. How much of a likelihood does my 1978 spray foam contain asbestos?

[silverloaf]

I don't recall the hearing of incidents or reading manufacture data sheets on the presence of asbestos in 2-part, closed cell, polyurethane spray-foam. Yes, we used masks and protective clothing when foaming in walls in buildings. The reaction of the two chemicals as it is applied creates conditions that are not healthy for lung or skin contact. Once it cures, the negative effects are dissipated.

When I trenched the foam in our trailer, I wore a mask to capture any dust particles. This is wise for any work performed in a closed environment.

The spray-foam that comes in a can is completely different. It is a one-part foam variant that reacts with air only. It is safe to apply with little or no side-effects. This makes it perfect for filling voids and cracks to ward off insects, Rodentia, etc. Again, use a mask as a precautionary measure.

Hope this helps.

[Lagniatte]

Many thanks.

When reflooring, has anyone thought to include or replace the lower layer of plywood with polywall? I'm thinking about reflooring with an initial 1/8" polywall, 1/8" hardboard with epoxy, insulation, then the top layer of plywood. The amount of rot I removed in the last couple weeks makes me want to make the floor as strong of a moisture barrier as possible (especially for the 1 1/2" strips under the wall U-channel).

Aside, I'm also thinking about replacing the wooden crossmembers on top of the frame with aluminum square tube.

[silverloaf]

We purchased our '88-30P in 2017. We went through an 18 month restoration process.

I had two major sources of water damage. The 1st was a long-leaking toilet that took out the floor and parts of the sub-frame.

The other was condensation delivered either directly or indirectly to wood and metal parts. The effects of condensation caused the outboard edge of the floor to rot where it met the aluminum exterior skin.

I also found rust and soft wood above the belly pan. I can point to the effects of condensation because the cavity above the pan has no ventilation. The moist air is trapped with no means of drying it out.

When replacing segments of the floor, I applied an automotive type of undercoating to anything outboard of the mainframe. I do not recall undercoating anything with the envelope of the frame.

When I re-installed the belly pan, I cut out the rectangular holes in the pan and installed some 4"x16" soffit vents. This provided a means of drying out any condensation and moist air. We don't do any winter camping so cold air infiltration is not an issue with the vents.

I used the OEM assembly method when re-constructing the floor. No fancy materials that would I call overkill. I'm not going live another 40 years, so what's the point?

We purchased our trailer from a party in Cadillac, Michigan. (we were originally from the Detroit area). Michigan has a cold and damp winters. When the temperature starts rising from snowy weather, the air reaches dewpoint, Then it's off to the races with condensation and its effects.

My advice to anyone considering a trailer above the Mason-Dixon line is to be cautious. There can be a lot of "sins" lurking in the "belly pan zone".

Good luck!