Fixing corners of vintage bondwood

[Murph]

Greetings All. I am restoring a 12ft Henderson bondwood circa 1955. I bought it as a shell. It has 6ml ply exterior and 3ml ply interior which I plan to cover with new 3ml ply (the interior walls that is). The rear wall has separated from one of the side walls and I understand that this is common. I have been told that before I do the internal fit out I need to secure the corners and not just rely on the cabinetry to keep the walls together. Any advice about securing the corners would be greatly appreciated. Many thanks, John

[Roehm3108]

Murph, are you talking about the framing or the cladding having separated? Can you post a pic of the problem area?

[Murph]

Hi True Blue. Thanks for your reply. I will send pic.

There was some rot in one of the rear corners on the outside which is requiring me to replace a section of ply around a metre high and 15cm wide. When I cut out the rotted piece I discovered that the framing in the area (layer upon layer of 6ply curved to the shape of the van on the corner and 20 mm x 30 mm horizontal softwood battens at 400mm centres on the flat sections) was suspect too (at the join) so I have replaced/repaired the corner framing with 6 ml marine ply strips glued with Sikaflex 221 (messy black stuff when layering thin strips of ply) and am about to repair/replace the rotted 20 x 30 battens. The rot spread a little to the inside 3ply layer and I will fix that too.

When I complete all this it seems to me that the joins will still be flimsily connected at the corner - just by glue and nails on a thin joining surface (although the rest of the van seems to have held together pretty well for nearly 60 years!).

I am particularly concerned about the holding capacity of the nails which will be hammered through the exterior ply at the corner to the profile (side) of the glued ply layered strip framing. After I remove the current paint job I plan to seal the corners with fibreglass tape and marine epoxy glue but this will only be a thin layer and not have much holding capacity.

Maybe I'm overly concerned, but it would be a messy job if the corners came apart after I have done the interior fit-out and painted the exterior of the van.

I'm keen to do everything I can at this stage of the restoration (short of using welded steel girders!) to reduce the possibility of this happening.

Best wishes, Murph (John)

[Murph]

Greetings,

Given the lack of responses to my question, I think I may have given a convoluted explanation on my first attempt so I'll have another go.

On a 60-year-old bondwood caravan that is currently a shell with a 6mm outer skin and a 3mm inner skin, will the installation of cabinetry alone hold the van together or do I need to give the van extra strength by using brackets, fibreglassing or some other method in the corners?

Many thanks,

John

[Roehm3108]

Hi John

I think we were all waiting for pics, as you mentioned that you were going to put some up. To answer your question in your last email, you will find that most vans are basically framed together via the rigidity of the overhead cabinetry, so that should be OK, once you fix the rot.

Instead of nailing things together, is it possible to use screws? there would be less chance of damage caused by the hammering. As well, if the rot is from water, make sure you get every bit of it out - better to overkill with the surgery than underkill. I had an instance where a restored van I had bought did not have the rot cut out properly and it continued to spread, even though it had been stored in a garage.

If you can put up pics, it is always better to see these things. Sometimes words don't do enough.

Cheers

[Franklin1]

G'day John,

I think your comment, "although the rest of the van seems to have held together pretty well for nearly 60 years!" answers your question. These vans do seem to hold together pretty well, with what sometimes seems like a minimum amount of timber and nails.

Assuming you are glueing and nailing all the parts together in that corner, I think you'll find it will be more than adequate. The internal ply will add to the rigidity of the framework, and the internal cabinets will increase that even more. As long as all your timberwork ends up combining together to make the van structurally sound, then I wouldn't be bothered with brackets or other additional fastenings such as fibreglass reinforcing.

My 1956 Franklin bondwood van has 19mm thick timber frames steam bent around the corners (where your laminated frame is), and the ply sheeting for the roof and sides is just nailed into the frame with small 20mm nails (no glue that I can see, or if there was any used, it's glueing power went a long time ago).

I towed that Franklin for over 1000kms on the day I bought it, wood rot in all four bottom corners and all. A lot less cabinets in it than you'd normally find in a van, because it was basically a shell. Arrived home with the van in the same condition as when I left the seller's place.

Old vans just seem to keep going.

cheers,
Al.

[Murph]

Many thanks True Blue and Al. My first photos didn't turn out well and the attached isn't that great either in relation to highlighting where the walls have come apart. The split is only about a metre long.

Your advice is reassuring. These vans look a little flimsy at a cursory glance, but clearly they are not especially when the cabinetry is installed. I guess if mine has been on the road for nearly 60 years that's a good indicator of its strength. When I removed the rotten bits (a fairly generous removal) it was clear that the glue had lost its holding and it was just the thin nails around the edges keeping the structure together. Pretty amazing.

I only had to drive my van 15 kms home but I was highly anxious because the fellow who sold it to me suggested that it could collapse like a house of cards if I wasn't careful. It was also the first time I had ever towed a caravan.

I suspect that the floor-to-ceiling wardrobe just inside the door of vans also plays a crucial role in strengthening the overall structure.

I plan to have a queen-size east-west bed so the framing for that should add even more strength.

Really appreciate your advice. Back to feeling more confident.

Cheers,

John

[King Fisher]

I have used sicaflex a lot on the restoration of my van. It not only holds and bonds well but it always stays flexible, allowing for some movement. With a few nails or screws to hold the wood till the sicaflex sets. On the modern vans the manufacturers use sickaflex between the two pieces of wood and simply staple the wood together, with a pneumatic staple gun, relying on the sicaflex and the attached cladding for the strength.

[Murph]

Hi kfisher. It's amazing stuff as I'm learning. I've got a whole fit-out to do yet so the Sicaflex 221 will be flowing at my place. Cheers.

[shesgotthelook]

Sory to hijack your thread but I'm wondering the same things with aluminium vans. After replacing water damaged frame, what is the best way to seal it all up again?
Should I use something like Denso tape on the timber then silicone on the aluminium or will that stand out too much?

[Franklin1]

G'day sgtl,

When you say, "will that stand out too much?", do you mean will it be too much waterproofing and make the cladding stand out too far from the frame?

One of the things I've noticed with the two aluminium vans that I've spent a fair bit of time restoring (not vintage, but same principle), is that there are a heap more places for water to seep in than on a bondwood van. It seems that with flat ply sheeting on walls and roofs, you can more easily make any joints watertight. On ali cladding that's fixed with screws or rivets, you have to make sure the highs and lows in the cladding profile are properly waterproofed, plus all the screw (or rivet) holes are all waterproof. I got caught out with one of my vans leaking six months after the resto was completed. Even though I'd pumped more sealant under the corner moulding covers than would be used on six vans in the factory these days, I still got a leak...from a screw hole. I can tell you I was well and truly pee'd off after all the effort I went to.

There are various ways of helping to minimise any possible water leaks affecting the frame, including the ideas you've suggested. I know of people who put sarking over the frame before putting the cladding back on (sarking is that silver stuff they put under tiles on house roofs).

I've even had a thought during the current bondwood project, that the Selleys Platinum polyurethane adhesive I'm using could be used like a paint to seal the surface of any timber. Once cured, it's waterproof to some degree, and I notice when I have to wipe any excess off any joints, the surrounding timber ends up being coated with a smear of the adhesive. Once it's cured, that surrounding timber seems like it would withstand water for a fair time.

I've often wondered whether smearing Sikaflex-type products over the surface of the timber in the corner frames would also act as a waterproofing layer.

I think with the various products available on the market these days, you could do all sorts of different things to protect the frame under the cladding, but I have to emphasize that the first line of defence is the most important line, and that is the sealant under the cover strip.

On the latest aluminium van I worked on, I took all the screws out of the cover strip and pumped mastic sealant down into each screw hole, and put the screws back into position. Before screwing the screw up completely, I pumped a small dab of sealant under the screw head, so that when I tightened the screw there was a layer of sealant stopping any water getting in. Call me "Over the top" if you like, but I do think you need to go to that sort of extent with the ali vans.

Hope this helps,

cheers,
Al.

[shesgotthelook]

Thanks Al, will take all that on board. What I meant with the silicone, is would it show up & look sloppy along the edges of the cap? Sorry if I'm using wrong terminology here,( gal ridge cap is what's in my head ).
That would have been heartbreaking to get a leak after so much work.

Just wish I had a 1/4 of the skill of you & many others on here ,but we'll keep plugging along & one day get these vans on the road.

[Roehm3108]

Note that Franklin1 said MASTIC, not silicone I reckon there should be a law against people using silicone as a caravan sealant. D-Mastic (available in white, grey and black) hardens on the outer skin but stays soft and flexible on the inside and is paintable.