Marine Ply or Tassie Oak

Hi Guys

Ive been a member of this forum for the last 10 years and have found plenty of good information and advise.
Ive never posted in the timber section before so here is my first post here.

Im in the process of rebuilding the roof of my pop top caravan, Due to the way these roofs are built there are some limitations.
Originally it was a sandwich panel of 0.75mm alloy sheet (Roof), polystyrene insulation and 3mm ply (Ceiling), with a timber perimeter and a few timber battens going across. Total thickness is about 23.5mm.
Im looking at re building with 1.5mm Fiberglass Sheet for the Roof and 3mm Ply for the ceiling, However im not sure what is a better timber to use for the battens,
Timber will need to be no thicker than 19mm and at a length of just under 2200 across the roof it will need to support the Fiberglass Roof as well as the weight of the plywood ceiling.
Ive looked at bunnings and i can get 18mm Marine Ply and cut battens out of that or i can get 19mm Tassie Oak at various widths and just need to cut to length.
Basically i need to know which is a stronger timber and which will sag less.

Im happy to take any of your advise on board if you have any for me.

Cheers

This may be a stupid question, but can the battens be fiber glassed to the fiber glass sheet?

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Originally Posted by Feckit

This may be a stupid question, but can the battens be fiber glassed to the fiber glass sheet?

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I'm no expert to fiber glassing but i think it can be, I dont know weather it would be a Good or Bad idea.

I would think that fiber glassed ribs would go along way to providing adequate supporting strength.

If you were using a whole sheet, or there abouts, I'd say ply, however you're not so I'd be using real wood.

Weight is important so something lighter than tassie oak may be better. Have no idea but guess meranti or Oregon would be lighter.

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Originally Posted by Pete57

Weight is important so something lighter than tassie oak may be better. Have no idea but guess meranti or Oregon would be lighter.

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Someone else has mentioned Meranti, I have had a look through bunnings and cant find any there.

If you were to wrap the timber in fibreglass you could even use urathane foam as the strength will be in the glass.
So any timber will do even pine or Western Red Cedar (which won’t rot if you get a leak) provided you wrap it in ‘glass.
H.

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Originally Posted by Jimako

Someone else has mentioned Meranti, I have had a look through bunnings and cant find any there.

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They may call the Meranti is often referred to as Maple, Bunnings does carry it. The ply cut in strips would not be as strong as any of the timber options available
I don’t know how dear the fibreglass sheet is to buy but you could consider doing some of the composite sandwich panels which would give you a finished product both sides and self support it’s own weight

Always thought Bunnings was full of Meranti

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Originally Posted by Beardy

They may call the Meranti is often referred to as Maple, Bunnings does carry it. The ply cut in strips would not be as strong as any of the timber options available
I don’t know how dear the fibreglass sheet is to buy but you could consider doing some of the composite sandwich panels which would give you a finished product both sides and self support it’s own weight

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I did consider the composite sandwich panels however i cant find it in my area, and it would also be complicated trying to get it home on a 6x4 trailer.
Fiberglass is costing me $33 per square meter, So i guess ill be heading back to bunnings to look for maple.

Cheers

Whilst i know its not timber but aluminium box tube may be a better option as it would be a lot stronger than 19mm meranti spaning 2.2m and would also help to keep your weight down