Suitable roof paint for water collection for domestic consumption
G'Day Folks,
I would appreciate some advice for paint suitable for a small section of roof over my wood shed, which is part of the rain collection used for domestic supply. The roof in question is only small, 2.4M x 4.2M, so a little over 10 sq metres in area. The closest specialist paint supplier to me is part of the Inspirations paint franchise, and I have always found them very good to deal with, but unfortunately on this occasion the only suitable paint that they had was only available in 10 Litre drums worth north of $200. They advised that as far as they knew only Wattyl had a suitable paint in smaller quantities but no one as far as he knew stocked it locally, although a hardware store 18Km away might have it. As it is a long weekend here, I phoned to see if they were open and if they had it and was assured that they had paint suitable for rainwater collection surfaces, so went over and collected it. The paint that they said all the local professional painters use for roofing was Haymes exterior Solar Shield, and again I discussed with the sales assistant the need for safe drinking water from the roof, and she did suggest that I divert the water for the first rain after the roof is painted, but after that it should be good for collection. The instructions on the 2 L paint tin were difficult to read, being small print in black on a darkish gold/brown background, but upon reading it all when I got home and had the tin in good light, I was surprised to learn that Haymes do not recommend this paint at all for roofing or contact surfaces.
I have not mentioned that I am painting this skillion roof because it has rusted severely. This is most likely because water from the main building which has a Colourbond and Zincalume roof runs over the galvanised skillion. I am aware that mixing galv with zincalume leads to rusting issues, but it has lasted 35 years so far, with no paint protection, so I am hoping that with some TLC now it may last another 20 years or so and then it will most likely be someone else's problem.
I have removed the iron at the moment and replaced some woodwork, a rafter and a purlin, the rest of the roofing timbers look pretty sound, although some has been affected by water leaking through over the years, so while the iron is off I plan to paint the wooden rafters and purlins, and I have already water blasted the iron and electric wire brushed the loose rust and applied Ranex rust converter. I want to paint it now on both sides and patch several pinhole rust penetrations with Sika polyurethane, then get it back up and fastened properly with roofing screws, (it was mainly fastened with clouts previously, most of which had come out, allowing water ingress), and then a final topcoat with the suitable roofing paint.
As a matter of interest, this galvanised iron profile resembles that used in domestic roller doors, it is not a profile usually used for roofing. There is a bit of this stuff around the place here, the original builder was a senior staff member at a large local plumbing concern, and the sheets are 1220 X 2400, and I suspect that they may have been some kind of cover sheet around rolls of colour bond iron sent out by Lysaghts to companies forming their own sheet metal profiles.
If you have waded this far, thank you very much, probably way too much waffle, but what I need is:
1.suitable non toxic paint.
2. available in 2L preferably quantities.
3.Colour is fairly flexible, I bought white gloss today, building is presently mostly faded brown Colourbond somewhat lighter than the present Colourbond Jasper, but there has been a small addition which just has a Zincalume roof and we have the galvo section I am discussing here. It is just a wood shed and we are out in the bush in NW Tasmania.
Thanks in advance for any insights,
Rob.
