Tangentially bike related - cleaning a polycarbonate roof

me-109 said:

When you say the sheets are 25mm, do you mean flat dual-wall construction or do you mean corrugated? I think corrugated ones would be a b1tch to paint and the roller would be likely to slide instead of roll (assuming you go across the corrugations or you need something very deep pile - like a mop!).
I'd be careful using boards across them. Even near a roof support it might be difficult to prevent flex and cracking of the polycarbonate if they are in contact.

Hey ME, definitely not the corrugated stuff, it's the dual wall stuff, much more hardy - yes if it was corrugated I would simply replace it - it is something like this:

MattFalle said:

instead of painting, why don't you fix up a Roman blind system like in conservatories?

That way you open and close as you want and you won't make your house look like you live in a scrapyard.

haha, yes a nice idea, and I did consider it, but on the inside I have a ton of big beefy joists, plus items stored up in the roof, so it would be one major undertaking to get everything down to even begin fitting them, plus the cost would likely be half the cost of simply new sheets that are not clear.

joeyhalloran said:

It's offtopic but how are you planning on painting it? Can you reach all parts with a ladder? A cherry picker? I presume it's not strong enough to walk on?

I used boards when I changed some of the washers a few years back, we have hefty joists at 1m intervals, and it was fine.
I plan to use boards to help me clean it, but to paint it my current plan is to use a 3m pole with a roller on the end, paint the top half from the front of the garage on a ladder, and the back half from the back of the garage, again on a ladder.

photonic69 said:

I thought you said the pitch was 1 degree? I'm confused.
That paint looks the business. It'll be pretty stinky and nasty to breathe in as it has Xylene as thinners. A bit like Hammerite paint. Don't bother trying to clean roller/brushes with the Xylene thinners as it will cost you more in thinners than buying a new roller/brush and just chuck them at the end. If it's like Hammerite have a spare roller/brush available as it might go off pretty quickly and become hard to use. They do warn you it won't be pretty from the inside looking up but as long as you get an even coat it will be fine from the outside. Just don't believe it will last as long as they say it will. If you have easy access to it to paint it at regular intervals it won't be an issue but if you need scaffold etc it starts to become expensive.

Our polycarb roof is 25 years old. I still walk on it with scaffold boards. Ours is only about 10-15mm single cell stuff.

Good luck. We want before and after pics and one from the inside looking up too

Ah unclear on my part - the original horrendous corrugated asbestos concrete sheeting had a generous 1 degree pitch, and a joint in the middle.
The previous owner of the house had attempted to stop water coming through by covering the joint, and in the gaps around it with expanding foam, and miraculously this did not make it water tight

These sheets were over a metal framework which is bolted to the sides, front and rear of the garage.
When I changed the roof, with the expect assistance of my now sadly late partners father, we came up with a way of locking the 6 (Or possibly 8) X 2 joists onto the existing metal frame work, and he had the genius idea of stacking two on top of each other, to yield either a 12 or 16" rise at the front, depending on the size of the joists.

So we now have a pretty decent pitch, and more storage space at the front, as the roof slopes down to the original height just as it reaches the rear wall - hope that make sense.

Yes I know they said it won't look that good from the inside, and if it were a part of the house, that may be a consideration, but it's a utilitarian space, so I genuinely couldn't care less, my only aim is to see if I can bring the temperature down to reasonable levels.

That's a really useful tip on the roller etc, thanks for that.
I've independently bought 500ml of Xylene, as that is what they recommend to thin it further, as by my calculations the 5 litres purchased will not quite manage two coats, but factoring in that extra 10% coverage, it should be fine - at the end of the day, even if I can't get two coats on the entire area, it should still be a sizable reduction in temperature.

Oh and as you seem to know about these things, do you think it is worth me buying a 7-10ll pot of some description to tip the paint and xylene into so I can mix it all up really well, I suspect hat is key to a decent finish.

I'll be intrigued to see how long it lasts, and how much dirt it attracts, although the latter is not that much of a concern.

I'm going to change the fixing gaskets before painting, as they lasted 7 years before they needed changing first time, so are 5 years old currently, and then hopefully I have no need to go up there again until 2029.

I'll keep the 3m extender bar thing, and then if I need to re-coat after a few years, hopefully it will not be too much of a hassle.

If it starts to flake off after a few months, then I'll clearly have to look at opal finish sheets, but I could do with those funds for other things now if possible :-)

I'll try and remember the pictures!

Ah interesting, thanks for that - I'll double check with them, though I know that's the specific, and only, thinner they recommend.