Tangentially bike related - cleaning a polycarbonate roof

daniel_b

Morning all,

about 12 years ago I changed the horrid flat concrete asbestos sheets (With a joint in the middle and a 1 degree pitch) on our garage for some lovely 6m long (No joints!) polycarbonate sheeting.

I forget the depth, but probably 25mm, nothing huge.

Anyway, I digress.

At the time I decided to go for clear sheets, as I thought the light would be awesome.
And yes it is, but unsurprisingly in the summer it can easily exceed 45 centigrade..

Both my partner and I turbo at times, and may wish to take part in an evening or daytime event on RGT for example, and unless I am wanting to lose a lot of weight, it's not really viable.

I have found reviews for a reflective paint, and am in fact awaiting it's arrival today, this needs to painted onto the top surface.

As with the vast majority of these tasks, the quality of the finish is all in the prep, so having spoken to the paint man, and looked online, it seems brushes are a no no, and that probably a microfibre cloth and some hot water with a small amount of washing up liquid should probably do the trick.

What occurred to me today, is that in the days when I owned a nice automobile, I have some left over citrus degreaser that was designed to be used to make the snowfoam stuff that is all the rage.
I never bought a suitable gun, but an acceptable solution was to put some in one of those pump spray weed things (To cover the weeds in weedkiller for example) and deploy it that way.

Does anyone think using that on the roof would be a bad idea?

Just thinking it might get the worst of it off, I could apply it on the bottom third of the roof, leave it for a few minutes, and then rinse it off, and then continue along.

Any informed opinions much appreciated - or in fact different methods/approaches.

To apply the paint I gather I need an low pile emulsion roller, and I have bought a Harris 3m extendable pole thing, which the roller should screw onto - I'm thinking that will mean I can paint the entire roof without actually being on it, which would be handy, though to clean in properly I will have to be up there on boards.

masjer

https://calpaclab.com/polycarbonate-chemical-compatibility-chart/

Citric acid is rated as A, so you should be fine.

masjer

Forgot to put detergents were A rated too.

daniel_b

masjer said:

Forgot to put detergents were A rated too.

Thankyou very much, looks like that could be a goer then, I've put time in for the whole thing next week, but I might try a small bit this weekend to see how it goes.

Appreciate your help :-)

photonic69

Seriously? Painting a Polycarbonate roof? How long you planning on keeping it? Can you see it from the house?

Anyway, I digress. I'm about to clean ours on our lean-to conservatory on the side of the house with a similar low-pitched roof. I just get a scaffold board, hose pipe and a bucket of hot soapy water and a soft broom. Give it a good wetting with hose then slop soapy water around and scrub with the brush. Hose clean. I need to do this once a year as ours goes manky over the winter. It's due about now so time to get the boards out if it's a nice weekend.

daniel_b

I'm not sure I get your point, maybe a misunderstanding.

The roof is visible from the house, but this is nothing to do with aesthetics/looks, all about trying to keep the temperature down in the garage.
The finish will be a plain grey colour, nothing pretty looking.

Ours has a pretty decent pitch, and is remarkably clean seeing as it is 12 years old now I think, and I have never washed it at all, the only reason I need to clean it is so I can apply the reflective paint which should then make it more usable in the summer months.

I gather these polycarbonate sheets are said to last 20-30 years, and when I bought them originally just the sheets weighed in at about 1k, pricing up opal finish replacements 12 years on, I think it's more like £1500.
The paint costs £100, so even if I had to repaint it every 5 years, it's quite the saving don't you think?

This is the paint: solarx.co.uk/window-film-services/solar-reflective-paints-coating/

me-109

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.

MattFalle

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.

joeyhalloran

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?

photonic69

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

daniel_b

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!

masjer

I'd be a bit careful with Xylene- D severe effect on the compatibility sheet.
It might be used (in the paint formula) to slightly melt the polycarbonate so the paint bonds.

daniel_b

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

masjer

If it's what they've recommended, it should be fine. It evaporates quickly, so its contact time will be short.

me-109

You've already bought the paint, so my other thoughts might not be much use....
Option 1, overlay of shed roofing felt; would need gluing down since you can't tack the centre parts over the roofing material. Easy lay (ooerr) and consistent finish, heavy but shouldn't be an issue.
Option 2, rubber roofing material, comes in large sheets and my get a garage out of one or two pieces. Glued down anyway, not tacked, so no holes. Nicer finish than felt and 10yr guarantee, usually.

photonic69

I wouldn't thin the whole lot with the Xylene at once. Maybe use 2/3 of the total. This is because once it's open it will start to go off and get gooey if it's anything like Hammerite based paints. Edit: You might need to add some of the last 1/3 later in the process to thin and also to clean the inevitable spills/off fingers etc.
If using a roller it takes a lot to get the roller fully wetted with paint. Keep replenishing roller frequently for the first few minutes.
Only pour out as much as you will use in a few minutes and keep the lid on the tin. Xylene is very volatile so will evaporate quickly and the paint will go sticky (possibly - I've never used that particular paint).
Do it on a cool, dry day with little wind (if at all possible).
It will take longer than you think.
Wear clothes you are likely never to wear again/overalls.
Get some rubberised palm, knitted gloves to keep the stuff off your hands. Get a few pairs from Screwfix. They are cheap.
Good luck