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Old 05-31-2010, 10:33 PM   #1
2 Rivet Member
1978 31' Excella 500
Tuttle , Oklahoma
Join Date: May 2010
Posts: 37
Original Plywood Thickness

Greetings from a noob,
I just purchased a 1978 31' Excella 500. I have found a small area of rot under the hot water heater. The rest of the floor that is visible looks fine.
My question is, what was the original thickness of the plywood sub floor?
Mine is 1/2" at the area where the rot is and appears to be that size everywhere else I can see the flooring.
The whole floor was carpeted. I pulled the carpet in the bath area to replace with something a little more appropriate but 1/2" seems pretty thin to me for the sub-floor.
The mount flange on the hot water heater was broken along one side which allowed the unit to sag downward and pull back from the outer skin on one side. I think that is how the wood got wet and subsequently rotten.
I want to replace all of the carpet eventually so suggestions on what to use will help.
Any advice or ideas will be appreciated.
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Old 05-31-2010, 11:00 PM   #2
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1967 26' Overlander
Winston Salem , North Carolina
Join Date: Oct 2007
Posts: 523
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The plywood is either 5/8" or 3/4".

My replacement carpet was a remnant purchased from Home Depot.
Winston Salem, NC
WBCCI 5218,
Corresponding Secretary Piedmont NC Unit 161,
1967 Overlander International.
1979 Avion 30ft rear bath
TV's 88 Chevy Suburban 454, 3:42, TH400
95 Cadillac FW Brougham, LT1,3:42, 7k tow pk.
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Old 06-01-2010, 05:41 AM   #3
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1993 21' Sovereign
Colfax , North Carolina
Join Date: Jun 2003
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The floor in our Sovereign is 3/4". You may have to hunt to find true 3/4" plywood, since the "new math" 3/4" plywood is 23/32" .
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Old 06-01-2010, 05:42 AM   #4
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1968 24' Tradewind
Oxford, , Mississippi
Join Date: May 2009
Posts: 1,564
The 60's had 5/8ths. I had a scrap from mine and a neighbor who had been in the plywood industry for 35 years looked at it. He that even marine grade plywood now does not have cores as solid as the old floor in my Airstream. I replaced rotten areas with AC exterior grade. As you probably know, today's 5/8 is actually not that thick (19/32 it think). I used shims made of 30lb roofing felt laid on the frame and outrigger rails to bring the new wood up to the level of the original an a couple of areas but under the water heater you won't have to worry about it being perfect. Make sure you cut the rot out so that the new piece meets on the top of a frame rail. The best tool I have fis the found to make the cuts is one of the vibrating saws from Harbor Freight ( like the multi-master you see on TV only $40.) The kerf is very small and it will get into areas you just can not get with a circular saw.
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Old 06-02-2010, 08:53 PM   #5
2 Rivet Member
1978 31' Excella 500
Tuttle , Oklahoma
Join Date: May 2010
Posts: 37
Well I guess a PO must have replaced at least some of the sub floor with 1/2" ply.
Mine is definitely not 5/8" or 3/4".
I am thinking my next step is to pull the carpet to find where the floor was replaced and then determine what needs to be done to fix it correctly.
I would surely like to have a long chat with the person that did this!
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Old 06-02-2010, 09:42 PM   #6
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1991 34' Excella
1963 26' Overlander
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It depends on the year

mine was 19/32 and thinned at the edges, it still had the printing visible.
Hi Ho Silver RV! Vernon, Sarah, Mac the Border Collie(RIP) -
A honkin' long 34' named AlumaTherapy
and a 26' '63 Overlander, Dolly
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Old 06-03-2010, 09:23 PM   #7
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1978 31' Excella 500
Tuttle , Oklahoma
Join Date: May 2010
Posts: 37
Okay, here is an update...Some good news some not so good.
The plywood subfloor is in a little better shape than I first thought but not near good enough.
The wood around the outer edges of the very rear rear of the trailer is not good. It doesn't appear to be connected to the bottom channel of the shell particularly at the very back.
There were several lag bolts bolted up through the bottom of the subfloor from inside the banana rap that were really not connected to anything. Some had actually veered off and were located between the outer skin and what was left of the subfloor.
I will be replacing the rear section of the subfloor but I am a little confused by what is there to connect to.
It appears there was really nothing to bolt through to connect the banana rap and frame/ subfloor to the shell, especially along the straight section of the back of the trailer just inside the hose storage area. I don't see any cross piece going from one side of the shell to the other in this area..
This has resulted in what I am assuming is the tail dragging effect I have read about in other posts.
There is a section of what looks like "C" channel going around the corner to about where the edge of the opening for the rear hatch is but it is laying on the long side of it's shape with the two short legs facing up ward. Is this correct?
I had assumed the "C" channel was standing upright with it's long side vertical allowing the subfloor to rest inside the the bottom lower short leg.
Upon reading what I have written so far, it seems logical that the "C" channel would rest on it's long side with the short legs facing upward to connect to the vertical ribs of the wall/shell.
What can I do to provide a rigid connection between the shell and frame/subfloor around the back of the trailer?
There are bolts/nuts going from inside the the shell through the subfloor and stringers but they are all forward of the curved part of the rear of the trailer.
There is no question the frame at the rear is falling away from the shell but I don't know what needs to be done to provide a good way of connecting the two back together.
Sorry for the long post but any advice/suggestions will be really appreciated.
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