This post describes the methods used to prevent steel rusting on the frame of my car port. I used two part epoxy resin paint when I repainted rusty sections after 19 years.
Nineteen years ago I replaced the original car port at my house, made of 2″ round steel tubing and asbestos sheet, with a new construction made of 3″ square steel tubing, covered in UPVC downpipe for protection, for vertical supports, 2″ and 3″ angle iron for horizontal supports, a wooden roof frame and corrugated UPVC roof and a UPVC facia.
Note: The square UPVC downpipe I used was a very good fit over the square steel tubing. It isn’t a tight fit the gap maybe as much as 2mm. The gap is just enough to allow the steel to be painted and for the downpipe to be slid over long lengths of steel with ease.
I intended this to last forever. Well it lasted nineteen years without much attention but eventually the exposed steel needed a little bit of paint and the screw caps holding the corrugated UPVC roof totally disintegrated letting the rainwater through.
The Process I Used To Prevent The Steel Rusting
Originally I was very careful to clean the steel very well, with an electric wire brush, and paint it with black Smoothrite paint (like Hammerite). Some of the steel was then covered with Waxoil to further prevent the steel rusting and the uprights with UPVC downpipe (used for rainwater normally). I wish I had covered all the steel with Waxoil, then none of it would have rusted.
This time I hope I have made a better job of it. Much of the Smoothrite paint was OK. So I rubbed down all the rusty patches with abrasive paper. You would be surprised how good the steel was underneath the rust. I then painted it with a two part epoxy resin paint mix. This consisted of a brown resin and a coloured (in my case black) hardener. The paint sets really hard and is difficult to cut with a wood chisel. (I had to get some paint runs off.) I did most of the painting before the rains at the end of 2012. It was then left exposed over winter. A few areas needed a bit more paint before I could put the roof on but I though it had survived exposure very well. It wasn’t easy to access some parts to either clean or apply paint but once the roof and facia are on no steel is exposed to rain but some is exposed to condensation.
I can certainly recommend two part epoxy resin paint to prevent steel rusting. It is expensive: EPOXY-MASTIC 121 from RUSTBUSTER two litres (1 resin, 1 hardener = 1:1 mix) and a tin of thinners cost £63.48 including VAT and postage. The theory behind its great benefit is: ordinary paint has large pigment which bridges over the top of rust allowing moist air to remain in the rust and continue to oxidise/corrode. Epoxy paint has no large pigment and soaks right into the rust even though it is very viscous. It is recommended on web sites that deal with rust on vintage automobiles.