Currently finishing off the frame for a DIY caravan (~3600x2200). Initially I was thinking of a trailer (but it morphed into a caravan) and hence I've had the concept of flooring it with 2.1mm checker plate steel (and rust proof painting it), but now wondering what's the best. I should be ok with weight with checker plate however it would always be nice to cut down on weight. Can I ask:
Q1 - What's the most popular DIY flooring material for caravans & why? (bit concerned re plywood re weatherproofing?) Q2 - If money and weight weren't a concern is checker plate a good choice? (or are there other reasons to use something other than checker plate) Q3 - Of the "plywood" options is there an obvious best choice re make/type and thickness? (assuming happy to pay a little more to ensure weatherproofing - want to buy something 'ready to go' so to speak) Q4 - Any suggestions re outlets to get products mentioned in Brisbane region?
blaze said
09:35 AM Aug 11, 2016
aluminium checker plate
Brenda and Alan said
09:56 AM Aug 11, 2016
My choice would be waterproof plywood for two reasons. Ply would offer much better thermal insulation. Metal would suffer badly from condensation forming inside in cold conditions. Probably not much difference weight wise as ply would be much thicker.
Alan
elliemike said
09:57 AM Aug 11, 2016
If you are walking on Metal Flooring it will be VERY COLD.
Steel Plate ! is unnecessary weight,
I would use Aluminium, then cover that (on top) with Marine Ply or something similar. Plain Aluminium sheet would be my choice as there is no need to have patterned sheet facing the road.
mixedup said
10:04 AM Aug 11, 2016
Brenda and Alan wrote:
Metal would suffer badly from condensation forming inside in cold conditions.
From a rust perspective do you mean Alan?
elliemike/Alan - Just noting too I might have confused things re underside versus what you walk on. When I had Steel CheckerPlate initially in mind the concept was to lay something carpet/lino over the top. Noting the feedback I'm thinking the concept of buying one product that is ready to go in terms of being (a) waterproof on underside and (b) has some thermal insulation. So the waterproof plywood concept sounds good. What specific water proof plywood would you recommend? For example:
Marine Ply
Film Face (non structural plywood), type of form ply?
-- Edited by mixedup on Thursday 11th of August 2016 10:05:29 AM
Dougwe said
10:33 AM Aug 11, 2016
Marine ply, mixedup. If it lasts in salt water it will last on land even better. You could also put a coat of a bitumen type surface on the underside as well for extra protection. The big green shed sell it in different size tins and just paints on.
mixedup said
11:02 AM Aug 11, 2016
ok thanks Dougwe
still curious to understand what Alan's comment re "Metal would suffer badly from condensation forming inside in cold conditions"? would be from a rust perspective?
macka17 said
11:28 AM Aug 11, 2016
No Need for Marine ply. 17mm or thicker "Form Ply " fine.
Just, as said. Cout lower face with bitumin/tar paint. comes in 4 ltr tins. 2 coats with sheepskin roller on 6.5mtr van gave enough to do chassis on two boat trailers too.
And a spray on Plastic coating on inner face, After cutting and b4 install gives instant interior floor finish for life.
8x4 sheets diagonally, just make sure you seal with epoxy along ALL edges first.
-- Edited by macka17 on Thursday 11th of August 2016 11:30:21 AM
mixedup said
01:19 PM Aug 11, 2016
thanks for the advice macka - hey can I ask:
re "Plastic coating on inner face" - did you have a product in mind? (e.g. what to get from Bunnings for example)
re "seal with epoxy along ALL edges" - did you have a product in mind?
Re why not Marine Ply - is it just to save on cost/weight I assume?
Jaahn said
04:51 PM Aug 11, 2016
Mixedup
I had a Winnebago previously, about a 1997 model made in Australia. It had a floor that was ply but faced underneath with a thin zincanneal sheet, I think it was. So that protected the wood from the water etc underneath. I though the Winne was well made when i did some mods and repairs.
I would think that formwork ply with a good coating of tar like stuff underneath would be OK. It also has a hard plastic finish to protect it against the moisture. The floor needs to be insulating as it can feel really cold so I would not consider metal at all. Marine ply is OK at three times the price too but why use that when you are not seeing the good looking outer veneers. That is the major difference to formwork ply. The glue is the same.
jaahn
Jaahn said
05:02 PM Aug 11, 2016
Hi mixedup,
Look here at this stuff, structural grade with a plastic covering and a grade A glue. Bunnings would sell it too. As shown usually 17mm is the common size.
Jaahn
FORMPLY - A BOND
Form Plywood from Mister Ply&Wood is manufactured to the structural requirements of AS/NZS 6669. FormPly is available in various stress grades and manufactured with a plastic overlay.
FormPly is a premium quality product designed and manufactured for fixed formwork applications.
The life of the formwork plywood depends on care and maintenance taken at the site and is reusable with good concreting practices.
FORMPLY - PHENOLIC OVERLAY - HWD STRUCTURAL TO AS/NZS 6669
Sheet size
(mm)
Sheet thickness
(mm)
Pack size
Approx weight
per sheet (kgs)
Code
1800x1200
17
50
24-25
fm181217
2400x1200
2400x1200
12
60
22-23
fm241212
17
50
32-33
fm241217
mixedup said
08:15 PM Aug 11, 2016
thanks Jaahn - looks good actually - would you still give a coat of "bitumin" paint on the underside?
As far as I can see looking at the product code numbers the non structural stuff is seconds ?? Probably OK for what you want if there is a saving. Might depend on what they have in stock. They are often the top and bottom sheets in the bundles that may be a bit damaged .
I might give it a coat of tar too.
Jaahn
FORMPLY - FILM FACE - NON STRUCTURAL PLYWOOD
Sheet size
(mm)
Sheet thickness
(mm)
Pack size
Approx weight
per sheet (kgs)
Code
1800x1200
17
40
24
fm1812172nd
2400x1200
2400x1200
17
40
32-33
fm2412172nd
FORMPLY - PHENOLIC OVERLAY - HWD STRUCTURAL TO AS/NZS 6669
Sheet size
(mm)
Sheet thickness
(mm)
Pack size
Approx weight
per sheet (kgs)
Code
1800x1200
17
50
24-25
fm181217
2400x1200
2400x1200
12
60
22-23
fm241212
17
50
32-33
fm241217
-- Edited by Jaahn on Thursday 11th of August 2016 09:15:14 PM
mixedup said
09:14 PM Aug 11, 2016
thanks - I'll go and have a look
macka17 said
09:47 PM Aug 11, 2016
That paint fine. I use similar
Marine ply is ALL Hardwood layers with Waterproof glues.
Top Formply we use on concrete forming (I used to drive cranes on a lot of Dams/Spillways. Bridges etc.
Is softwood inner layers with waterproof glues and the two outer layers of timber, Hardwood.
we used a lot on boat floors.
I wouldn't recommend anything less for a long term project.
BUT... Being softwood inners, If you don't soak in and seal the edges.Properly
The softwood rots away. fairly quickly.
With Epoxy. get a same size tin of thinners with your two pack. Blend the 3 evenly for first coupla coats.
It'll soak right in.
Then coupla coats of normal mix over top of.
I had a timber yacht yrs ago.
Teak/Mahogany with full length Jarrah planking/Ribs
With ironbark keelson/stempost/sternpost.
Beautiful but 35 yr old when I acquired her and neglected a bit.
with a few(hmmm) soft spots topsides..
I learnt to inject those mixxes quite skillfully too to preserve the beautiful timbers..
after drying out the hand carved/shaped teak with blower first.
I used to love caulking those seams.
I learnt that in '40's with fishing boats and tar on beach rollers back home..
Any 2 pack epoxy mixes will do job. Marine ones better but $$$.
Oh. You'll buy 2+ sheets of A grade Formply for 1 sheet of Marine.
That galv sheet Underlay under van flooring is not really a good idea either.
I know a couple (one of them mine) of Off roaders. that got wet a lot Underneath.
If not 100% sealed from each other, (Impossible)
The water gets through. Can't get back out. so rots the ply...
Good Ply at least 17mm (depending on chassis rail spacing.)
Epoxy sealed ALL round the edges of each sheet, b4 mounting
Bitumined underneath. Chassis rails too. Sealed inside, Will last forever.
A quick light sand over of sheet surfaces a good idea too.
That stuff has an Oily? coating over them. To stop the concrete sticking.
even b4 the crews oil them for job.
If you go to paint supplies. they have blends of plastic type Coatings
that you can Spray.roller, pour. on surface. and it seals completely.
Much easier AND internally waterproofing than most other coating.
VERY much easier, and quicker to apply.
OH.
and use some BOLTS.. as well as screws and glue to fasten body to itself and chassis.
Unless ally. In which case the bolts will be fine by themselves hey.
With a bit of help from Mr MIG.
Have fun
bill12 said
06:27 AM Aug 12, 2016
I started with 7mm cd structural ply for the floor of my slide on, but found it to thin and flexible so I added another layer. The 17mm form ply would have been a better choice. Ply is much cheaper than any sort od metal flooring. Thanks, Bill .
elliemike said
09:49 AM Aug 12, 2016
There were posts on line recently I was reading about coating the underside of Plywood flooring (not sure if it was on this GN Forum !) The were those against using Bitumen type Underseal coatings. Those for Plain paint or leave it bare. Underseals do not allow the ply to breath, and therefore promote rot was one theory.
I just paint mine with good quality black paint as it is easier for me to apply (actually did it again 2 weeks ago) Yearly Routine maintenance for me.
Interested to see what other peoples thoughts are.
Although Aluminium and ply on top would be the same not allowing the ply to breathe ! . But heaps of off roader campers built like that ? I would have no problem in building it like Ply on Ally myself.
Jaahn said
10:12 AM Aug 12, 2016
Hi
I think it depends on what you are going to subject the van to on your travels. If you want to take it easy and travel on good roads and stay at 'normal' places then there is no problem at all. The more off road and wet weather and river crossings you do the better you should seal it off from underneath and the better it will last. The ply will breathe from the top where it is hoped it is dry IMHO
Macka has some good ideas for sealing it with epoxy and that is boat standard. He is correct in saying the inner plies of formply are softwood and may not be as durable as proper waterproof ply. However if there is no excessive moisture get into it, there is no problem. Where I worked they used formply for everything. Tanks, bins, small structures etc as it was cheap, easy to work with, and needed no painting or extra work. They just sealed the edges and joints with silastic sealant and screwed it together for water tanks and the like. No problems over some years, even longer for some projects. Reused it if it came apart easily. However for your own use I would seal the edges as Macka says. Then protect the underneath with a bit of thicker tar stuff for extra protection.
Jaahn
-- Edited by Jaahn on Friday 12th of August 2016 02:11:23 PM
macka17 said
02:00 PM Aug 12, 2016
Jaan.
Peolpe have to remember that up here and further North in tropics.
We get rained on a but (quite heavy at times.)
Travelling on roads in those conditions. NO different to submerging in creeks. actually more so.
as it pressure blasted in off wheels and bounce back.
I've bitumined several vans over the yrs. Underneath.Incl this one. All chassis too over galv.
Compass in '98. still fine. Mate owns it. and he goes bush a lot (off roader)
The best stuff I find is that Tar/mastic coating they sell for under wheel arches
In shed too lazy to look.
Ply will ONLY form mould and dry rot (That's a misnamer if ever there one, Caused by fresh water only in marine environment) if moisture accesses it.
I've seen PROPERLY sealed and tarp coated/sealed ply yacht decks 50 /60 yrs and older.
Still 100% dry/good when boat scrapped for timbers.
Treated proper like. It's as good as anything.
Just deteriorates faster than most if neglected or not treated properly in first place.
Structural and std ply is total rubbish timber, glued together.
Don't touch it. (my opinions only)
And DO NOT use SIkaflex for sealing round edges in this applic..
Soaking in epoxy's or . cheaper. Thinned down varnish (Not so good) is the only long lived way.
Then seal joint between sheets with Sika if you like,
ALL Silicons will leak past. SIkaflex and 3M Marine the best ones.
It's an awful shame we can't pass on all our expertises to younger people ain't it.
Some of the things I've done in my lifetime you wouldn't believe.
robol said
09:38 AM Aug 13, 2016
Hi Mixedup, macka17's advice is great advice, bus's are constructed with ply floors with a bitumen paint underneath and they are made with a million kilometres in mind. A word of caution, don't be tempted to use Liquid Nails or similar because of its cheaper price on either the floor or cabinetry. These adhesives dry hard and do not flex. Sikaflex is an excellent product.
Cheers Rob.
macka17 said
02:31 PM Aug 13, 2016
Yea Robol.
A lot of boat yards have gone over to the 3m and some Bostic Marine adhesives.
Near as good as Sika and half the price (nearly)
Sika Deck seam is still the only one for that job though. but messy as.
Another word of advice.
If starting fresh with making van.
Make the body of in one solid piece. Complete. free standing. Modular.
Then plonk onto chassis and bolt down.
It'll be a much more substantial item and last much longer/less leaks too.
Mate made one. 18ft 6 inside Off roader, almost.
Ally angle frame with same for stringers and ribs. Box section floor section stringers. ALL welded. with Rivetted ally gussett plates in all corners. crossovers.
Ext solid ally sheeting (not interlink sections) rivetted and epoxy'd to framework.
Ply floor. Insulation interior walls and roof with light veneer cladding glued and screwed over.
Single ring beam loom, one high. one low. with LED's to suit at whatever places.
240v in sleeve in chassis with junctions up for wall sockets.
Worked out real well.
Showroom full lounge. leather. Drop down queen bed over the top of..
Bathroom. Kitchen.
He was a ships carpenter by trade. I did a lot of his MIG for him.
He left around 2 yrs ago. Haven't seen him since.
His first one . he converted a horse box truck to motorhome.
Profit from that almost built this one.
Aus-Kiwi said
02:56 PM Aug 13, 2016
Ply with 'plenty" of metal support .Its flexing that crests leaks etc . Some marine ply is not treated and can rot ..
Krusty said
10:15 AM Aug 14, 2016
I've seen marine carpet on the floor. Not checker plate, just aluminium flooring.
Brenda and Alan said
04:27 PM Aug 14, 2016
Mixedup condensation forming on cold metal on the inside of van could cause corrosion but mildew /mould would also be a major problem.
Currently finishing off the frame for a DIY caravan (~3600x2200). Initially I was thinking of a trailer (but it morphed into a caravan) and hence I've had the concept of flooring it with 2.1mm checker plate steel (and rust proof painting it), but now wondering what's the best. I should be ok with weight with checker plate however it would always be nice to cut down on weight. Can I ask:
Q1 - What's the most popular DIY flooring material for caravans & why? (bit concerned re plywood re weatherproofing?)
Q2 - If money and weight weren't a concern is checker plate a good choice? (or are there other reasons to use something other than checker plate)
Q3 - Of the "plywood" options is there an obvious best choice re make/type and thickness? (assuming happy to pay a little more to ensure weatherproofing - want to buy something 'ready to go' so to speak)
Q4 - Any suggestions re outlets to get products mentioned in Brisbane region?
My choice would be waterproof plywood for two reasons. Ply would offer much better thermal insulation. Metal would suffer badly from condensation forming inside in cold conditions. Probably not much difference weight wise as ply would be much thicker.
Alan
If you are walking on Metal Flooring it will be VERY COLD.
Steel Plate ! is unnecessary weight,
I would use Aluminium, then cover that (on top) with Marine Ply or something similar. Plain Aluminium sheet would be my choice as there is no need to have patterned sheet facing the road.
From a rust perspective do you mean Alan?
elliemike/Alan - Just noting too I might have confused things re underside versus what you walk on. When I had Steel CheckerPlate initially in mind the concept was to lay something carpet/lino over the top. Noting the feedback I'm thinking the concept of buying one product that is ready to go in terms of being (a) waterproof on underside and (b) has some thermal insulation. So the waterproof plywood concept sounds good. What specific water proof plywood would you recommend? For example:
-- Edited by mixedup on Thursday 11th of August 2016 10:05:29 AM
ok thanks Dougwe
still curious to understand what Alan's comment re "Metal would suffer badly from condensation forming inside in cold conditions"? would be from a rust perspective?
No Need for Marine ply.
17mm or thicker "Form Ply " fine.
Just, as said.
Cout lower face with bitumin/tar paint. comes in 4 ltr tins.
2 coats with sheepskin roller on 6.5mtr van gave enough to do chassis on two boat trailers too.
And a spray on Plastic coating on inner face, After cutting and b4 install
gives instant interior floor finish for life.
8x4 sheets diagonally, just make sure you seal with epoxy along ALL edges first.
-- Edited by macka17 on Thursday 11th of August 2016 11:30:21 AM
thanks for the advice macka - hey can I ask:
Re why not Marine Ply - is it just to save on cost/weight I assume?
Mixedup
I had a Winnebago previously, about a 1997 model made in Australia. It had a floor that was ply but faced underneath with a thin zincanneal sheet, I think it was. So that protected the wood from the water etc underneath. I though the Winne was well made when i did some mods and repairs.
I would think that formwork ply with a good coating of tar like stuff underneath would be OK. It also has a hard plastic finish to protect it against the moisture. The floor needs to be insulating as it can feel really cold so I would not consider metal at all. Marine ply is OK at three times the price too but why use that when you are not seeing the good looking outer veneers.
That is the major difference to formwork ply. The glue is the same.
jaahn
Hi mixedup,
Look here at this stuff, structural grade with a plastic covering and a grade A glue. Bunnings would sell it too. As shown usually 17mm is the common size.
Jaahn
FORMPLY - A BOND
FormPly is a premium quality product designed and manufactured for fixed formwork applications.
The life of the formwork plywood depends on care and maintenance taken at the site and is reusable with good concreting practices.
Actually how about non-structural Film Face? www.misterplywood.com.au/Products/Plywood/NonStructuralPlywood.aspx I did google it and seems to becoming popular blog.maxiplywood.com.au/formply-or-film-face-plywood-the-facts-explained.
Hi
As far as I can see looking at the product code numbers the non structural stuff is seconds ?? Probably OK for what you want if there is a saving. Might depend on what they have in stock. They are often the top and bottom sheets in the bundles that may be a bit damaged .
I might give it a coat of tar too.
Jaahn
-- Edited by Jaahn on Thursday 11th of August 2016 09:15:14 PM
Marine ply is ALL Hardwood layers with Waterproof glues.
Top Formply we use on concrete forming (I used to drive cranes on a lot of Dams/Spillways. Bridges etc.
Is softwood inner layers with waterproof glues and the two outer layers of timber, Hardwood.
we used a lot on boat floors.
I wouldn't recommend anything less for a long term project.
BUT... Being softwood inners, If you don't soak in and seal the edges.Properly
The softwood rots away. fairly quickly.
With Epoxy. get a same size tin of thinners with your two pack. Blend the 3 evenly for first coupla coats.
It'll soak right in.
Then coupla coats of normal mix over top of.
I had a timber yacht yrs ago.
Teak/Mahogany with full length Jarrah planking/Ribs
With ironbark keelson/stempost/sternpost.
Beautiful but 35 yr old when I acquired her and neglected a bit.
with a few(hmmm) soft spots topsides..
I learnt to inject those mixxes quite skillfully too to preserve the beautiful timbers..
after drying out the hand carved/shaped teak with blower first.
I used to love caulking those seams.
I learnt that in '40's with fishing boats and tar on beach rollers back home..
Any 2 pack epoxy mixes will do job. Marine ones better but $$$.
Oh. You'll buy 2+ sheets of A grade Formply for 1 sheet of Marine.
That galv sheet Underlay under van flooring is not really a good idea either.
I know a couple (one of them mine) of Off roaders. that got wet a lot Underneath.
If not 100% sealed from each other, (Impossible)
The water gets through. Can't get back out. so rots the ply...
Good Ply at least 17mm (depending on chassis rail spacing.)
Epoxy sealed ALL round the edges of each sheet, b4 mounting
Bitumined underneath. Chassis rails too. Sealed inside, Will last forever.
A quick light sand over of sheet surfaces a good idea too.
That stuff has an Oily? coating over them. To stop the concrete sticking.
even b4 the crews oil them for job.
If you go to paint supplies. they have blends of plastic type Coatings
that you can Spray.roller, pour. on surface. and it seals completely.
Much easier AND internally waterproofing than most other coating.
VERY much easier, and quicker to apply.
OH.
and use some BOLTS.. as well as screws and glue to fasten body to itself and chassis.
Unless ally. In which case the bolts will be fine by themselves hey.
With a bit of help from Mr MIG.
Have fun
There were posts on line recently I was reading about coating the underside of Plywood flooring (not sure if it was on this GN Forum !) The were those against using Bitumen type Underseal coatings. Those for Plain paint or leave it bare. Underseals do not allow the ply to breath, and therefore promote rot was one theory.
I just paint mine with good quality black paint as it is easier for me to apply (actually did it again 2 weeks ago) Yearly Routine maintenance for me.
Interested to see what other peoples thoughts are.
Although Aluminium and ply on top would be the same not allowing the ply to breathe ! . But heaps of off roader campers built like that ? I would have no problem in building it like Ply on Ally myself.
Hi
I think it depends on what you are going to subject the van to on your travels. If you want to take it easy and travel on good roads and stay at 'normal' places then there is no problem at all. The more off road and wet weather and river crossings you do the better you should seal it off from underneath and the better it will last. The ply will breathe from the top where it is hoped it is dry
IMHO
Macka has some good ideas for sealing it with epoxy and that is boat standard. He is correct in saying the inner plies of formply are softwood and may not be as durable as proper waterproof ply. However if there is no excessive moisture get into it, there is no problem. Where I worked they used formply for everything. Tanks, bins, small structures etc as it was cheap, easy to work with, and needed no painting or extra work. They just sealed the edges and joints with silastic sealant and screwed it together for water tanks and the like. No problems over some years, even longer for some projects. Reused it if it came apart easily. However for your own use I would seal the edges as Macka says. Then protect the underneath with a bit of thicker tar stuff for extra protection.
Jaahn
-- Edited by Jaahn on Friday 12th of August 2016 02:11:23 PM
Peolpe have to remember that up here and further North in tropics.
We get rained on a but (quite heavy at times.)
Travelling on roads in those conditions. NO different to submerging in creeks. actually more so.
as it pressure blasted in off wheels and bounce back.
I've bitumined several vans over the yrs. Underneath.Incl this one. All chassis too over galv.
Compass in '98. still fine. Mate owns it. and he goes bush a lot (off roader)
The best stuff I find is that Tar/mastic coating they sell for under wheel arches
In shed too lazy to look.
Ply will ONLY form mould and dry rot (That's a misnamer if ever there one, Caused by fresh water only in marine environment) if moisture accesses it.
I've seen PROPERLY sealed and tarp coated/sealed ply yacht decks 50 /60 yrs and older.
Still 100% dry/good when boat scrapped for timbers.
Treated proper like. It's as good as anything.
Just deteriorates faster than most if neglected or not treated properly in first place.
Structural and std ply is total rubbish timber, glued together.
Don't touch it. (my opinions only)
And DO NOT use SIkaflex for sealing round edges in this applic..
Soaking in epoxy's or . cheaper. Thinned down varnish (Not so good) is the only long lived way.
Then seal joint between sheets with Sika if you like,
ALL Silicons will leak past. SIkaflex and 3M Marine the best ones.
It's an awful shame we can't pass on all our expertises to younger people ain't it.
Some of the things I've done in my lifetime you wouldn't believe.
Cheers Rob.
A lot of boat yards have gone over to the 3m and some Bostic Marine adhesives.
Near as good as Sika and half the price (nearly)
Sika Deck seam is still the only one for that job though. but messy as.
Another word of advice.
If starting fresh with making van.
Make the body of in one solid piece. Complete. free standing. Modular.
Then plonk onto chassis and bolt down.
It'll be a much more substantial item and last much longer/less leaks too.
Mate made one. 18ft 6 inside Off roader, almost.
Ally angle frame with same for stringers and ribs. Box section floor section stringers. ALL welded. with Rivetted ally gussett plates in all corners. crossovers.
Ext solid ally sheeting (not interlink sections) rivetted and epoxy'd to framework.
Ply floor. Insulation interior walls and roof with light veneer cladding glued and screwed over.
Single ring beam loom, one high. one low. with LED's to suit at whatever places.
240v in sleeve in chassis with junctions up for wall sockets.
Worked out real well.
Showroom full lounge. leather. Drop down queen bed over the top of..
Bathroom. Kitchen.
He was a ships carpenter by trade. I did a lot of his MIG for him.
He left around 2 yrs ago. Haven't seen him since.
His first one . he converted a horse box truck to motorhome.
Profit from that almost built this one.
Mixedup condensation forming on cold metal on the inside of van could cause corrosion but mildew /mould would also be a major problem.
Alan