# Box Making Plywood/Marine ply Project 898



## teemyob (Nov 22, 2005)

Hello,

I need to build a Box under the main floor of the Motorhome to house some euipment. The underside will be exposed to the elements when on the road.

What type or what is the technical term for the type of ply I need?
Also would Bitumen pain be okay to seal and waterproof it?

Also need some aluminium trim to sit a trap door over the top of the recessed box to support it this shape..............

___
.....|___

What do I term this as?

(Ignore the dots, only way I could get the shape to display)

Hope someone can help?

Trev.


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## Zebedee (Oct 3, 2007)

Hi Trev

Just "Marine Ply" as far as I know - if you can get it. Get some with as many laminates as you can in the thickness you want.

Cheap it ain't, but it is the best. 

Bituminous paint will do the job well, but be aware that it never really dries out and will be sticky and horrible for ages. _(Why not use marine varnish, which does dry to a hard finish. It works on boats!!)_

Hope this helps

Dave


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## bigfoot (May 16, 2005)

A good type of varnish is the 2can poly eurathene variety Varnish and hardener.
You need to have everything prepared It goes off in minutes but the finish is like bulletproof glass..
Put fibreglass tape and resin in and on the joints both external and internal to make it really bombproof


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## Pudsey_Bear (Sep 25, 2008)

How much weight do you want to put in it Trev?

Kev


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## teemyob (Nov 22, 2005)

*Weight*



Kev_n_Liz said:


> How much weight do you want to put in it Trev?
> 
> Kev


Hello Kev,

Approx 25kG

Thanks Dave, Bigfoot and Kev.

Trev.


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## Pudsey_Bear (Sep 25, 2008)

Sorry Trev,

I meant to ask for dims of the box, have you gone down the lateral route IE, does something the right size exist already that can be coerced into use, or have you considered making a fibreglass box around a cardboard box, I'm a big fan of the KISS principal.

But don't tell Zebedee I've gone right off him.

Kev.


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## teemyob (Nov 22, 2005)

*Dimms*

Kev,

The Approximate dimensions are min

710mm Long x
400mm Wide x
280mm Deep

Trev.


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## Pudsey_Bear (Sep 25, 2008)

That's a biggish box, if you wanted to go the FG route, I don't know if you've ever used it before, if not, it's quite straight forward to make a box, it doesn't have to be the right sized box, I've made them from parts of bigger boxes, and used carton sealing tape to get the desired size, you only use the cardboard as a mould, but can also be incorporated to be used as structural reinforcement of the FG, as can simple rolled up newspaper, as it's the resin which gives it its strength, and can be hugely strong as well as being 100% waterproof, except for the lid of course, as for the Aluminium, I think it's called a rebated bend or something like that, hope that give you some help.

Kev.

PS and it's very light too, much lighter than Plywood.


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## Zebedee (Oct 3, 2007)

Kev_n_Liz said:


> But don't tell Zebedee I've gone right off him.
> Kev.


Didn't realise you fancied me in the first place Kev. :?

I always seem to find these things out too late!  

++++++++++++++++++++++++++++++++++++​
*Trev* There's some stuff called sandwich board (or something similar) which the professional glass fibre people use for making panels.

It comes in flat sheets and is immensely strong when a couple of layers of fibreglass matting have been added to one or both sides.

If you could get some of that it would be perfect for the job. Why not ring your nearest motorhome manufacturer and ask who does their fibreglass work for them. I've no doubt the scent of a couple of fivers would get you all the offcuts you need for the box. 8)

Hope this helps

Dave


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## vicdicdoc (May 14, 2005)

teemyob said:


> . . . I need to build a Box under the main floor of the Motorhome to house some euipment. The underside will be exposed to the elements when on the road.


Been there - done that and ended up covering it in sheet aluminium as it wasn't as strong as I'd hoped . . in the end it done the job as intended but the weight of it went up out of proportion to the stuff being carried [you'll need to ensure the fixings are well secured - which in my case meant surrounding the box with metal strip bands of approx 1/8" inch thick.


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## tincan (Jul 31, 2006)

I think a box of the size needed could do with some metal strapping to secure it in place whether in FG or ply. 25kgs bouncing around on the road will vibrate like bu**ery and place undue strain on joints and corners. A simple flat aluminium strap could save you losing the whole deal on a motorway somewhere. Maybe if you check how underfloor safes are fitted it would help point you in the right direction. I also think the common term for the trim you require is a z section extrusion.

Noel


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## 104477 (May 13, 2007)

Just a tad of advice,

Marine ply is guaranteed to have no voids ( air pockets in the laminations ) which is perfect if you are building the hull of an ocean going yacht. Hence the expense.
However, WBP grade plywood ( good quality from a timber merchant not a DIY shed) will be up to the job even with the occasional void, as long as either is varnished, painted with bitumastic paint or painted with Wests system epoxy which is a good waterproof glue too then you should get a long service life from it.
Reinforcing the joins with Glass fibre tape would be a bonus.

Rob.


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## teemyob (Nov 22, 2005)

*Replies*

Hello all,

Thanks for all your replies.

To put you in the picture so-to-speak, below are a few images.


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## Zebedee (Oct 3, 2007)

Bit of lateral thinking needed here Trev. 8) 

If you search around I bet you could find a strong plastic box of about the dimensions you want.

If you then bond its rim to your Z section alloy framing with Sikaflex it will be very strong and totally waterproof - and dead easy to install.

No building of the box, no varnishing, no maintenance, no hassle!   

That's what I would try first. :wink: 

Dave


Addendum. Just had a look in the Screwfix catalogue, and they do one in "high impact polystyrene for heavy duty use".

Dimensions are 600 x 400 x 200.

Not quite what you want, but not a mile away, and only 14 quid.


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## teemyob (Nov 22, 2005)

*Chassis*

Last Photo


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## motaman (Mar 25, 2007)

*box making*

trev from an engineering point of view. forget marine ply ,too heavy , too long to make ,too expensive and will not stand up to the elements long term .looking at your photos i assume you want to access from the inside.
buy a plastic storage box from screw fix, u need a high impact polypropalene , which most of them are. it will out last your camper.they do them quite near to your size, if not put two side by side. u can cut the hole smaller so that when it is let in it will sit on the frame of the box. if u want it a flush fit cut some 4mm plates to fit under the upper frame of the box and bolt thro or no8 s tappers hope this helps regards gary


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## motaman (Mar 25, 2007)

*box making*

oops trev er indoors just spotted similiar suggestion, must b the way to go
gary


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## Zebedee (Oct 3, 2007)

*Re: box making*



motaman said:


> buy a plastic storage box from screw fix, u need a high impact polypropalene , which most of them are.


Beat you to it Gary!   

I've been waiting a long time for this - it's usually someone else who gets in before me. 

Where's the emoticon for a smug grin!!
:wink:   
Dave


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## motaman (Mar 25, 2007)

*box making*

dave, dont care ,so there, my mum reckons i'm clever
gary


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## teemyob (Nov 22, 2005)

*Project*

Thanks again everyone, to enlighten you all the idea is to house this.










Dometic HB2500

The product size is

710 Long
400 Wide
280 Deep

As the vents will need to exit and the return air vent be inculded so the box length needs to be more like 810

Trev.


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