1988 Toyota Odyssey Complete Restoration

[prasi00]

Hi All,

I am the very excited owner of a properly dilapidated Toyota Odyssey. Engine and chassis are not in a bad state, but body is badly affected by damp.

It needs a lot of work but priority 1 is to stop the water ingress.

Roof is made up of grp, with some Styrofoam for insulation and wooden struts plus steal frame. The wood is badly rotten and the metal rusted. Side walls are mostly ok apart from the wall under one of the windows which is rotten through.

I am deliberating what to do with the roof.

There are two distinct routes I can take.

1. Try to make the new roof slightly convex so it does not collect water. To do this:

Make roof rafters by taking fairly large cross cut battens say 12cm, and tapering them to 2.5 cm at the edges to achieve slope. Use 5.5mm plywood to cover them on top. Insulation in the middle. 3mm ply at the bottom

2. Go with the flat roof, clean the tar (doh) previous owner has used from the fiberglass outer, put new rafters from a) wood or b ) aluminium and insulation in the middle and 3mm ply at the bottom.

Option 2 should keep overall weight down, but will create risk of pooling water again.

In both instances the final roof finish will be liquid EPDM rubber.

I will not use the roof for storage or walking.

Another option I am considering instead of using plywood is to use GRP sheeting. 2mm x2400mm x 1200mm costs around the gbp 90 mark vs around 12gbp for 3mm ply. But even if I get a leak in future the structural rigidity of the roof will not be affected and in theory it will be much easier to fix.

In terms of aluminium profiles vs wood rafters, aliminium is lighter, will not rot. It is not much more expensive but it is hard to work with.

Finally what insulation thickness to go for in the roof? I am contemplating between 25mm celoflex rigid boards and 50mm.

Hugely excited from what is ahead.

Looking forward to hear what you think.

Nikolay

[jjrbus]

Welcome and good luck with the Odyssey. I cannot help as I know little about them. On the roof though I would add as much insulation as practically possible. The Toy's are woefully under insulated.

Happy Holidays Jim SW FL

[zero]

I like the idea of new convex rafters. Your use of the metric system is making my head hurt though. You are talking about having the rafters around 4 3/4" in the center and tapering to 1" on the ends, if I am converter those damn CMs correctly. I did the same with 3" in the middle and 1 1/2" on the ends and it was plenty strong. But much has to do with the species of wood you use. I used white oak. Some woods at 2" are stronger then others at 3".

When it comes to plywood - again -species of wood is the key. Second to that is the amount of plies. You mentioned 5.5 mm plywood for the exterior that I guess is around 1/5". Seems WAY too thin to me.. 3/8", four-ply, marine plywood made from fir or beech is what I'd use. Motorhome companies get away with thinner materials because they glue multiple plies together to form a sort of engineered truss. Winnebago, e.g., uses 3/8" plywood on the exterior, then a layer of 3/4" or 1" foam, and then a layer of 1/4" plywood and all three plies are glued together to form a unit.

[jjrbus]

Many places where you buy what is listed as 1/4" plywood it will actually be 5.5 mm, which is slightly thinner, about 7/32". Some rail and stile router bit sets come with a choice of actual 1/4" or 5.5mm cutters for this reason.

If using arched roof trusses and roof air I would try to leave a "flat" spot where the roof air will be. Jim

[Back East Don]

Just a quick note. The manufacturers data states that the liquid EDPM on both wood and aluminum requires the proflex primer. Otherwise a great roof choice.

[prasi00]

Thanks a lot guys, I will post a few photos as I progress. At this stage all the photos I have are of rotten plywood and water damage, so I will hold off till I have some improvement to show.

Starting with removing the tar from the roof on Sunday. I will go with the 2 x1inch insulation boards for the roof, and will glue them together, should add a bit of extra rigidity. I also like the idea of the convex roof, but it does add to the job and I don't have facilities to do it properly. I have to work outside in the middle of winter in London (plenty of rain). I have decided to instead replace the old framework for the roof while keeping the aluminium top in place.

[jhjeff]

How did the roof project go? Curious on the extent of the water damage you found and what it took to repair it. 

[freebear13]

Having the correct tools, knowing someone with the correct tools, or hiring someone with the correct tools is KEY. I am in the school of belief of trying your best to get our vehicles back close to the way they were built- a slightly convex shape to our roofs...crucial to not let that water pool up top. For the years in between the time I knew I needed to rebuild my roof correctly and finally doing it I used to have to park it with two by fours under the tires front and back of one side to make up for the sagging roof. 

     I am not sure if our friend here across the pond got around to completing his project but I just finally posted pics from my spring of 2015 roof job on my 1985 Toyota Dolphin Motorhome.