IAN zzz wrote:

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Is this faulty design or poor workmanship?

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Both.

The best DIY construction in my view is to use fibreglass/polyurethane/fibreglass sandwich panel.

Get the pieces supplied as a "flat pack" and glue it together with Sikaflex.

It will not leak and it will also be much stronger and lighter than most commercially built vans.

http://vanglass.homestead.com/index.html

Speaking from experience.

Cheers,

Peter

IAN zzz wrote:

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I've just commenced building an 18' totally off grid van.  One of the most important aspects for me is that it DOES NOT LEAK. 

Online research and anecdotal evidence suggests that perhaps a HUGE percentage of vans less than 10 years old leak.  Stories of roof leaks, window leaks, seam and corner leaks appear to be very common.

Is this faulty design or poor workmanship?

I'd be very interested to read your thoughts.

Stay safe.

 

 Hi Ian zzz, I prefer the older, frame and cladding method myself. I'd garrantee my little 11footer wont leak, its two years old. Most of my van building techniques stem from asking hundreds of questions to professionals.

 

A galvanised frame can be as small as 13x13mm tube steel at 0.56 kg per metre with 15x15 angle on edges. 13mm tube has a negative. When a 10mm tech screw is used it will hit the other end of the tube. This means that once you tap tge hole of the screw remove the screw, cut off the drill end of the screw and screw it in. Alternatively use 15mm tube.  Welding including gusseted joins makes it strong with some small amount of flex...perfect. I also added what I call a "rollbar". Hidden inside east west walls is a braced rollbar to keep it all square.  At the top of the rollbar on the exterior of the wall I welded two eyelets. These are used to tie the van down in heavy  winds which occured in SA on our lap...100 kph winds would have sent our 748kg atm van flying.

 

So, waterproofing. The wall cladding goes on first, stucco finish is my preference. I used steerivets.The wall cladding should extend say 30-50mm below the floor level where the angle frame should extend to thus no seepage into the van.

Keep adding cladding to fill the walls. I didnt us glue just good silicone sealer on the cladding to exterior frame.

The roof cladding initially should be wider than the van say 100mm each side or more (it comes in 2400 width). Mark under the cladding 10mm out from the wall. Remove cladding and cut it. This process is because if you cut the cladding a total of 15mm wider than the van and the van frame was say 5mm out of square your roof cladding wont remain 7mm overlap on each side...a leak will occur.

 

Once cut place the cladding on the roof with 11rc on the middle metre of the cladding to the roof frame allow section to dry then finish the cladding. Grab your corner angle caravan lengths. Doing it in sections squeeze sealant or 11rc into the gap of the edge and the angle of the frame then hammer the 7mm of excess cladding over the edge. Sealant under the corner outside angles and roof cladding and screw it down with 20mm tech screws (sealant under head of the screw) every 500mm, before and after bends. Screw will go through the corner piece, roof cladding then the frame angle. Use 20mm self drilling tech screws. When corner piece is being bent around  a bend do it slowly and use your rubber mallet to mould the edges that want to spray away from the 90degree point.

 

Mop up along the way with rag and turps. At the end fit the concave rubber strip into the corner piece thereby covering the screws.

 

So as you can see, there are no screw holes in the roof except through the corner piece. The cladding is hammered over on the cladding edges so it cant leak.

 

Finally, solar panels. 11rc is ultra strong to glue panel mounts and vent frames onto the roof. The wires are an issue. What I did was use pvc pipe. Running from under the caravan floor through inside an internal wall then through the roof is a 20mm pipe. Wires can go through the pipe. Were it comes up through the roof cladding drill a hole in the cladding say 5mm and make many cuts so the the pipe can go through. Seal it then seal the end of the pipe and wires. If water ever went through it will go straight to the ground!. I also used a 100x50mm visible pipe for my shower hose and on/off swich etc (see pic of shower pipe is what shower head is hung on- sorry I cant rotate it). This means these items are always accessible, not hidden away in a wall.

There are other things. side Hatchs...if they are large pick the twin lock type. Single lock can allow rain to enter in the corners. Dont skimp on door quality. Making it too high will interfere with an awning, too low it has head clearance issues. An internal step or pull out step is far better than a mobile step alone.

 

Step down distance to the ground can be worked out depending on whether off road or tar only and wheel size. Eg in my on road next van if using 13" wheels if I have 2.5" drop axle I'll have a desirable 200mm step to ground. 14" wheels maybe 4" drop axle

Floor. I use 12mm lightweight ply painted on side. Then coat two coats of a membrane and two coats of any left over  house paint. This is all for the underside of the van AND the ply edges. The boards should be tongue and groove.

 

Joist ends should be plugged with plastic  plugs.  Chassis ends with the same or welded plates. I prefer to vover wiring along the exterior of the chassis not inside it ...with plastic wire covering. More accessible. 

 

Antenna, I used "foldaway antenna" and comes with exterior wall mounts. No leaks. If installing a shower I place the joists lower than the floor joists.  If lowered then the ramifications of a leak is contained within that area.

Hope thst helps. Tony

 

 

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-- Edited by Eaglemax on Thursday 2nd of August 2018 09:11:37 PM

Another source of leaking occurs with aluminium clad caravans and that is by capillary action up and over the joint seams.We had a serious leak at one window that we removed three times to reseal by various methods with no success.

When we reclad the van for different reasons the cause became apparent as can be seen from the pic. Upon recladding all the joints were sealed to prevent this happening and no more leaking window. We also found that the sealing foam the the industry uses for windows etc. is very poor quality and used instead a much more expensive closed cell foam tape on all windows doors etc.

Alan

''Tin & sticks'' caravans leak more often than fiberglass sandwich panel caravans purely because there are more joints to leak.

Aus-Kiwi wrote:

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This is the problem ( one of them) with light weight construction. Flex becomes an issue. Less sealant in joints to save weight , lighter screws etc to save weight . The old equal & opposit reactions apply here . To get weight down to be legal to tow ..

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 With stick and tin construction, that is true, but it does not apply to sandwich panel construction.

Cheers,

Peter

Peter_n_Margaret wrote:

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Aus-Kiwi wrote:

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This is the problem ( one of them) with light weight construction. Flex becomes an issue. Less sealant in joints to save weight , lighter screws etc to save weight . The old equal & opposit reactions apply here . To get weight down to be legal to tow ..

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 With stick and tin construction, that is true, but it does not apply to sandwich panel construction.

Cheers,

Peter

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 Thats obviously true. However there are many people out there that want to build their own caravan  because they cant afford to build/buy one with a sandwich panel system.

Our 11 footer cost about $9,000. Add accessories and you still had change out of $12,000. Anyone advocating sandwich panels know their cost?

 

The nearest small caravan with toilet and shower is the Euro...over twice the price which I think is fibreglass. That same senario  is with larger vans. I'd wonder what the cheapest  sandwich panel small van would cost. ..I think I saw one for $33,000.

 

It's an emerging issue for battlers. People nowadays just talk of better solutions as if the net income of all caravanners is massive, self funded retirees or prime inheritance. 

 

We towed our van on a lap with a diesel i30 Hyundai. Fuel cost was $1,900 for around 19,000 kms. Being disability pensioners building our own van that was quite an achievement. Use sandwich panels we couldnt go!

 

How about we consider cheaper alternatives for the home builder eh? Correct me if you know its a cheaper alternative.

Tony

Good ideas AK.

Tony ... you've hit the nail on the head there mate. ALL the points you mention are true and valid for my personal situation. I can't buy what I want ... so I'll build it. I daresay the internal finish may not be all that fantastic. But I know what I want and I WILL BE 100% SURE it will be strong, functional and WILL NOT LEAK :)

Aus-Kiwi ... Both your comments make sense and give me confidence :) Thank you

John ... I must live on a different planet! Or I have the ability to attract only those with leaky vans. Hopefully we will get a few responses mentioning leaks :)

Stay safe

I think it could also be alot of us buy off the used market.
Much like a car, I guess you have to expect it to not be like a new one off the showroom floor and expect some issues.
I think leaks just tend to be the first thing to show up.
That said, on working on my jacyo, I'm constantly surprised( and I shouldn't be at this point) the crap work done on sticking it together.
Often it can't be seen until you look 'under the hood' then all sorts of things rear their ugly heads.
Seriously, I can't understand how someone with a staple gun can stuff up such a simple job so badly. Some of them holding panels on don't even go into anything.

Don't even start me on how difficult it can be to put a screw in straight

-- Edited by denmonkey on Saturday 4th of August 2018 11:35:04 PM

-- Edited by denmonkey on Saturday 4th of August 2018 11:35:45 PM

Gday...

So now 550+ views and still not a single member, apart from me, that has a van that has not or does not leak.

I find this incredulous ... hundreds of thousands of vans on the road and mine is the only one that doesn't leak. 

C'mon folk ... who else has a van that hasn't, or doesn't, leak?????? 

Cheers - John

Gday...

I understand what ya mean Keith ... have seen them meself.

However, there is not the slightest discolouration or damp spots or slightest smell or any indication of any moisture ingress in any cupboard or any of the 'joining' places that usually give signs if one looks closely.

Some outside panels were replaced about four years ... fixing a parking indiscretion of mine. 

There was no indication of anything amiss then either. However, I remain vigilant but still no leaks.

OH - once again - hundreds of thousands of vans on the road and it seems I am the only one that hasn't had or got a leak ... get out  it's not possible.

cheers - John 

-- Edited by rockylizard on Sunday 5th of August 2018 04:00:39 PM

Hi Rocky. Our 2011 24' Jayco Sterling has only leaked once when I left a solar panel cable entry point not sealed over night!! No other leaks up until this time.

Aussie Paul.