putting this up as a discussion point after a conversation with a friend who is thinking about doing it.
the caravan is about 9 years old and in fairly good condition. He is a little concerned that the underside of the
floor may be showing signs of wear. He is considering painting the under of the floor with a tar based paint
to seal it from any ingress of water.
therefore I would ask for your comments on this topic as there maybe others who are interested in this topic.
i will also put it up on the tech section as well
thank you
briche
macka17 said
12:08 AM Oct 15, 2016
Spray or brush.
I've done both on several.
To Me. Brush is best. half the money not spent on Aeresol and thinners.
Preferably in hot weather so it runs and soaks in better.
I usually use the stuff they sell in Supercheap etc for under wheel arches and chassis.
I've always done it.
Normally clean off suspension/axle units and spray them with rust proof/galv paint too.
Black plastic sheet. OLD shirt Long sleeved, high collar, and rubber gloves.
It drips everywhere.
Just remember it drips so work Away from job. not under it.
or you'll be trimming your hair.
Footprints said
12:40 PM Oct 15, 2016
I can not help re weather proofing existing vans however on my van I have light galvanised sheeting laid firstly on top of the chassis and the floor laid on top of that effectively sealing underside of floor to the elements.
Cheers, Allen
Aus-Kiwi said
04:31 PM Oct 15, 2016
I used some swimming pool membrane paint then four coats of acrylic house paint . Mainly due to being left over from other jobs ., some critical areas I used some thin alloy sheet .. Was a little concerned about wood breathing if or when water got in there ? All good though . I Gould the membrane penetrated the wood giving way better protection . From memory it was called Base cote off eBay ..
-- Edited by Aus-Kiwi on Saturday 15th of October 2016 04:33:44 PM
macka17 said
07:40 PM Oct 15, 2016
Galv sheeting under the ply was tried by Roadstar in the beginning with the Off/Semi offroaders.
but they stopped. as the timber was rotting when water got between the two.
I know. I had a Compass in '90's that did that.
Only 5 yrs old too. but did a lot of creek crossings etc.
Most important. No matter what you use.
Is to get penetration with first coat.
Weedpharma said
08:06 PM Oct 15, 2016
What is the forum rule on double posting in two forums? This is also in Techies
Weedpharma
-- Edited by Weedpharma on Saturday 15th of October 2016 08:07:49 PM
Vince said
11:36 PM Oct 15, 2016
Only advice I can offer is - If the underside is galvanised sheeting DO NOT paint it.
Painting anything galvanised unless done to a proper specification can deteriorate the coating and limit its effect to deal with atmospheric conditions.
My Regal has galvanised frame and sheet under the floor all I do is hose it down and it's still all solid after 12 years with no signs of deterioration
Cheers
Vince
Tony Bev said
01:39 AM Oct 16, 2016
Vince wrote:
Only advice I can offer is - If the underside is galvanised sheeting DO NOT paint it.
Painting anything galvanised unless done to a proper specification can deteriorate the coating and limit its effect to deal with atmospheric conditions.
My Regal has galvanised frame and sheet under the floor all I do is hose it down and it's still all solid after 12 years with no signs of deterioration
Cheers Vince
Thanks for that info Vince, it was something that I was unaware of
macka17 said
11:37 AM Oct 16, 2016
Did you do much water crossings with yours Vince.
Mine lived in creeks and on beach up North.
If you painting Galv.
wipe with acetone first to remove any coatings.
Then spray with cold Galv.
If any deterioration started. grind that back to metal first.
or you just kick starting second explosion of rust
under fresh coatings.
Although the protection the galv has under vans.
the average 8 to 10 yrs doesn't really apply.
Aus-Kiwi said
11:51 AM Oct 16, 2016
It's when water gets under paint . Or any coating Much the same with alloy too . Our farm equipment. We would just spray with used engine oil with a little diesel added to soak in . From farm trucks, harrows, tractors .Even wood on farm sheds . Using pasture spray equipment ..
Vince said
05:37 PM Oct 16, 2016
macka17 wrote:
Did you do much water crossings with yours Vince.
Mine lived in creeks and on beach up North.
If you painting Galv. wipe with acetone first to remove any coatings. Then spray with cold Galv. If any deterioration started. grind that back to metal first. or you just kick starting second explosion of rust under fresh coatings.
Although the protection the galv has under vans. the average 8 to 10 yrs doesn't really apply.
I don't know the history of our van I've only had it 14 months.
Worked in the sheet metal trade for 36 years and learnt a bit about galvanising.
As I stated in my OP use a proper spec to paint gal or it will be a futile effort.
The cold Gal paint you are using is ok as long as you use an etch primer first. Good to see you use a spray on method.
You should also apply a top coat which in gal specs is a two pac application as the etch primer and cold galv paints are porous.
In days of old when paint contained lead, if you painted galvanised anything with it that was the start of the end for the coating.
The lead reacts with the tin and causes the galvanised coating to erode and what happens is water ingresses between the two surfaces
and then oxidation starts. Oh and if using coal tar epoxy use an etch primer first.
Cheers
Vince
vince56 said
08:18 AM Oct 17, 2016
My thoughts would be that if the floor is going to have issues at all with moisture it would be where the floor panels sit on the frame where moisture can get trapped.
Very difficult to prevent unless you sealed around the frame against the floor or removed the floor and completely painted the panels for replacement (which you wouldn't)!
briche said
09:10 AM Oct 17, 2016
Thanks to you all for your comments plenty of things to consider
putting this up as a discussion point after a conversation with a friend who is thinking about doing it.
the caravan is about 9 years old and in fairly good condition. He is a little concerned that the underside of the
floor may be showing signs of wear. He is considering painting the under of the floor with a tar based paint
to seal it from any ingress of water.
therefore I would ask for your comments on this topic as there maybe others who are interested in this topic.
i will also put it up on the tech section as well
thank you
briche
I've done both on several.
To Me. Brush is best. half the money not spent on Aeresol and thinners.
Preferably in hot weather so it runs and soaks in better.
I usually use the stuff they sell in Supercheap etc for under wheel arches and chassis.
I've always done it.
Normally clean off suspension/axle units and spray them with rust proof/galv paint too.
Black plastic sheet. OLD shirt Long sleeved, high collar, and rubber gloves.
It drips everywhere.
Just remember it drips so work Away from job. not under it.
or you'll be trimming your hair.
I can not help re weather proofing existing vans however on my van I have light galvanised sheeting laid firstly on top of the chassis and the floor laid on top of that effectively sealing underside of floor to the elements.
Cheers, Allen
I used some swimming pool membrane paint then four coats of acrylic house paint . Mainly due to being left over from other jobs ., some critical areas I used some thin alloy sheet .. Was a little concerned about wood breathing if or when water got in there ? All good though . I Gould the membrane penetrated the wood giving way better protection . From memory it was called Base cote off eBay ..
-- Edited by Aus-Kiwi on Saturday 15th of October 2016 04:33:44 PM
but they stopped. as the timber was rotting when water got between the two.
I know. I had a Compass in '90's that did that.
Only 5 yrs old too. but did a lot of creek crossings etc.
Most important. No matter what you use.
Is to get penetration with first coat.
What is the forum rule on double posting in two forums? This is also in Techies
Weedpharma
-- Edited by Weedpharma on Saturday 15th of October 2016 08:07:49 PM
Painting anything galvanised unless done to a proper specification can deteriorate the coating and limit its effect to deal with atmospheric conditions.
My Regal has galvanised frame and sheet under the floor all I do is hose it down and it's still all solid after 12 years with no signs of deterioration
Cheers
Vince
Thanks for that info Vince, it was something that I was unaware of
Mine lived in creeks and on beach up North.
If you painting Galv.
wipe with acetone first to remove any coatings.
Then spray with cold Galv.
If any deterioration started. grind that back to metal first.
or you just kick starting second explosion of rust
under fresh coatings.
Although the protection the galv has under vans.
the average 8 to 10 yrs doesn't really apply.
I don't know the history of our van I've only had it 14 months.
Worked in the sheet metal trade for 36 years and learnt a bit about galvanising.
As I stated in my OP use a proper spec to paint gal or it will be a futile effort.
The cold Gal paint you are using is ok as long as you use an etch primer first. Good to see you use a spray on method.
You should also apply a top coat which in gal specs is a two pac application as the etch primer and cold galv paints are porous.
In days of old when paint contained lead, if you painted galvanised anything with it that was the start of the end for the coating.
The lead reacts with the tin and causes the galvanised coating to erode and what happens is water ingresses between the two surfaces
and then oxidation starts. Oh and if using coal tar epoxy use an etch primer first.
Cheers
Vince
Very difficult to prevent unless you sealed around the frame against the floor or removed the floor and completely painted the panels for replacement (which you wouldn't)!
Thanks to you all for your comments plenty of things to consider
briche