Timbers and screws

[becks]

Hi All,

I have acquired myself a caravan in need of a full restore. I am so excited 


20180306_085515 by Bec Trimmer, on Flickr

20180311_164753 by Bec Trimmer, on Flickr

Screenshot_20180302-102440 by Bec Trimmer, on Flickr

Screenshot_20180302-102440 by Bec Trimmer, on Flickr

I believe it is a 1963 home built caravan because we discovered a 1963 The Age in some of the front cladding. She is named the "The Roxy"

IMG_20180304_185806_252 by Bec Trimmer, on Flickr

I was a little concerned about being able to rebuild the framework, but it turns out the shape is made using a structural hardwood ply with some support rails.
This is what it looks like now;

20180312_190108 by Bec Trimmer, on Flickr

Question 1.
What type of wood should I use for support rails? I have had Meranti suggested, but I have also seen pine used to make repairs. I do need a narrow profile. Would there be any other hardwood suggestions? or what is common.

Question 2.
The screws needed to reattach the aluminium sheeting are galv, but the only ones I can commonly find are self tapping for metal work, are they more of a specialty product? I was hoping to avoid flat head screws, because I hate them alot!

[neilncheryl]

Hi Becks
I would not use pine as it tends to rot quicker than other timbers. Meranti is what I use and trim it to size.
If you get a piece much wider than needed you can cut a few pieces from it.
Remember that you won't find the right size as your van was built using imperial sizes and today's timbers are cut to metric sizes.
After I have replaced the damage I paint the timber frame with Norseal Wood Treatment which will prevent future rot.
Be careful with the screws you use as metal screws have a corrosive reaction to aluminium and will corrode your aluminium sheets.
Enjoy the build, I always do
Cheers Neil

[Mustang]

Re your framing sizes:
Several older vans had the interior framing exposed to the inside.

You could use larger timbers for strength & paint the inside between the framing or just loose a little interior space & line over the larger frame.

[Franklin1]

G'day becks,

In the days that these caravans were built, the common timbers used were oregon, mountain ash (also called alpine ash), and various pine species. Nowadays these timber types are hard to find, so alternatives have to be used, and meranti pine is probably the one most commonly used for current caravan construction. Radiata pine that is now used in house frames is certainly an option, but you do have to make sure you are using good quality timber that is free from any knots likely to fracture when the van is wobbling along the highways. Tasmanian oak is another suitable timber for framing if you can get it - it's used in some of the Porta Moulding product range (available at Bunnings and other suppliers).

For fixing the aluminium cladding to the timber framework, you really need to be determined to use slot-head screws in a 1963 caravan, and more importantly, they must be stainless steel screws (or you are asking for trouble with corrosion problems in the years ahead). Classic Fasteners in Sth Aust sell suitable 'pan head' screws - I would recommend you use 8 gauge in either 3/4" or 1" length (depending on your timber frame dimension - the longer the screw, the better).

Details of the 8-gauge stainless steel pan head in various lengths can be found here: Classic Fasteners . Note that if you click on the [VIEW DETAILS] box to the right of the "Self Tapper Pan HD Slot Stainless 8G x 1" listing, the pop-up screen will give you more details, including a current offer "Buy 200 or above and get 50% off". That would mean that instead of paying $15 for 100 screws, you'll get 200 screws for the same amount - and that's a very good price compared with what you would pay at other outlets for the same type of screw (for example, Bunnings currently sell 8g x 25mm S/S pan head screws for $17.34 per pack of 100 - see here ).

Hope this helps.

Your van should be a real beauty when you've finished working on it.

cheers,
Al

[Franklin1]

G'day again becks,

I will amend the recommendation I gave above about the screw gauge size that you would use to fix the cladding onto the timber framework. Many years ago when I was a lad (about the time your van was built), an 8-gauge screw had a shank diameter of 1/8" (3mm). Now it seems that manufacturers have upscaled the sizes, so that an 8-gauge is now 4mm, and a 6-gauge is now 3mm (...must be something to do with our Western diet ).

Looking at the Classic Fasteners website, the following info is shown:

Screw gauge size      Thread shank diameter    Pan head diameter

6                                3.5mm                            6.86mm max

8                                4.2mm                            8.18mm max


Your existing screws might match the 6-gauge dimensions more closely, which would be the better option if that's the case.

cheers,
Al.

[becks]

Thanks for the suggestions neilncheryl, Mustang and Franklin1.

I had planned to source the meranti and the frame is exposed to the inside, mainly around the windows, only the front and back are lined with ply. So thanks for confirming that.

Can I clarify also Franklin1, I thought I wasn't to use stainless because it would react to the metal? I am not sure if the metal sheeting is aluminium or tin.

Thanks,
Bec

[Franklin1]

G'day Bec,

Based on your photos, I would be 99.99% confident the sheeting is aluminium. A fridge magnet will tell you one way or the other - the magnet won't stick if it's' aluminium.

Corrosion between two different metals in contact with each other is a complex technical issue, and your eyes will glaze over if I attempt to explain what goes on. Small stainless steel screws fixed through a large area of aluminium are the most cost-effective method of fixing, and giving appropriate corrosion resistance in the process.  You will get better corrosion resistance using either chrome-plated or nickel-plated brass screws, but the cost will be quite a bit higher.

I restored a 1977 Millard poptop caravan that had aluminium cladding fixed to a timber frame. Every screw used in the factory was stainless steel, and after 35 years, there was no indication of any corrosion under the screw heads.

Contrast this with a 1992 Windsor van I had for a period of time recently. All the screws used around this van were zinc-plated, and the majority of them showed significant corrosion after only 20 years.

cheers,
Al.

[cardygeorge]

I'll back up the Stainless Steel and aluminum. My van has a steel frame with aluminum cladding. It had stainless screws, but after 60 years of contact the steel frame had corroded every panel of cladding so I'm in the process of cleaning the frame and replace every single aluminum panel......

[starburst]

Meranti is a very straight grained lightweight hardwood and a good choice for caravan framing. It's not rated as very durable when exposed to moisture & the elements so is probably no better than Radiiata pine for durability BUT it may be stronger & more stable. Kiln dried Mountain Ash & Tassie Oak are the same thing, a little heavier and more durable, and available at Bunnings and many other hardwares. Oregon, a very strong and stable lightweight softwood, is the probably one of the best timbers to use but is now very expensive unless sourced from demolition yards & secondhand dealers. Stainless screws into aluminium have been used in the caravan industry for 60 years and show very low degree of corrosion. Good luck with your project! Cheers, Arthur

[Mustang]

When I restored our 41 y/o aluminium clad/alum/framed Viscount I recycled a good number of S/S screws, mostly only the heads wanted polishing & very little if any signs of corrosion, I also used a sealant in the threads.

[becks]

Brilliant, thanks alot! It is becoming clearer

[gerrynshaz]

I used meranti on my clipper restoration(still going)
Bought it in bigger dimensions than my frame size and ripped it down.on my triton.
if u live in melbourne i can give u the address of where i bought my meranti from.
if you want to have a look at some photos of my frame resto go to members photo album and search clipper.
go to the post 'our clipper resto' created by 'gerrynshaz'
email:[e-mail]
goodluck
cheers

[waynet63]

Mar 20, 2018 8:36:59 GMT 10 Mustang said:

When I restored our 41 y/o aluminium clad/alum/framed Viscount I recycled a good number of S/S screws, mostly only the heads wanted polishing & very little if any signs of corrosion, I also used a sealant in the threads.

Hey Mustang, I'm resealing the 'J' rails on my 2 millard vans, I was thinking of using 'loctite' as a sealent for the threads.
What did you use and recommend pls
YoursWayne

[Mustang]

Hi Waynet63,
I've never had an issue with mastic (its a sealer not an adhesive) if you need to dismantle again its easy.
Loctite I believe would be ok metal to metal, but would have little strength in fiberglass or wood.

If you remove the J rails, clean them thoroughly & apply silicone so it seals from the inside out, you will never have to touch them again, that said you would not be able to remove them either without a lot of issues.
Cheers

[waynet63]

Thanks Mustang for your fast and knowledgable reply. I was thinking of using the 25mm 'Mastik Tape' to seal under the 'J' rails, (after fully cleaning everything) and then using silicon for the roof fittings and cross seams, I have 2 types, 1 is bostik and the other is a Soudal product.
My main problem I think is that I have ants in the walls and ceiling.
Where I have my vans and live was just covered with water for about 16 months, not floded per see but just continual rain,. so the ants have made a home in what appear to be the walls ceiling.
Thanks for your time
Wayne

[Roehm3108]

If you want all things slot-headed, Keables in West Footscray are the place to go. Google them, I think you may even be able to order online these days.

I built my replica gypsy using treated pine house stud timber and ripped it to size, after finding that meranti was twice the cost!

[Mustang]

Apr 6, 2023 12:10:05 GMT 10 waynet63 said:

Soudal product.
My main problem I think is that I have ants in the walls and ceiling.
Where I have my vans and live was just covered with water for about 16 months, not floded per see but just continual rain,. so the ants have made a home in what appear to be the walls ceiling.

Hi Wayne,
Give yourself the best chance, get rid of the ants & do not try & seal over a damp surface.
Soudal is an excellent product. (apparently made by the original owners of Sikaflex)

Post some images of your project.

link

[stevefranklin]

Hi waynet63,
i am currently working on a 67 Franklin and using sikaflex for my windows, i think this would be ok for sealing under the screws, what i do before remounting the aluminium panels is cover a match in aquadhere and insert into existing screw holes and break off end, this will give you a tight fit when you re-screw the panels
i think i will give the mastic tape a try for my trim between walls and roof, might be a bit less messy than the sausage

[supreme78]

The preferred product is V60 by Bostik. its not acidic like other roof and gutter sealants and although its a bit more expensive it works very well and does not stink like silicone. I used to in the Reso of my 1978 Viscount supreme and now using it on my 1990 Evernew resto