Twin Wall Polycarbonate

[niall Y]

I've spent a whole chunk of this summer, sorting out the outside of the house (that is, when it wasn't raining) - painting and doing running repairs. I'm now approaching the home stretch, which includes doing some work on a lean-to, we use as a utility room.

Having removed the gutter, I spent a couple of hours, painstakingly poking out the very soggy, algae/moss. that has grown up from the bottom of the roof, inside each of the rectangular cavities, which I have to admit was both therapeutic and disgusting , at the same time. In some cases it had grown up to an inch inside the hollows

. It was installed 11 years ago and the ends were carefully taped, and end caps fitted, as per instructions. It has in this time kept out the "fauna",, but certainly not the " flora"

My question to other Forum users is - " Is this to be expected of Twin/Triple Wall Polycarbonate?" In other words - "Is this as good as it gets with this system of roofing?"

 

[flying haggis]

I have twin wall glazing on one of the greenhouses and I get the ingress you mention, but as its a green house it doesnt bother me (yet?) and I had taped the end s as you did

 

[niall Y]

I have twin wall glazing on one of the greenhouses and I get the ingress you mention, but as its a green house it doesnt bother me (yet?) and I had taped the end s as you did

Thanks for the reply. I suspect that this is what one has to expect. After all water is delivered to the end of the roofing every time it rains, and if microscopic spores find their way in , then they have their own mini -greenhouses.

 

[Robbo3]

I have twinwall for a carport (approx 10m x 3m) & as an infill between two buildings. Both have a very shallow slope & suffer from ingress of algae & muck.
My shed/workshop, a concrete sectional garage also has a twinwall roof at a steeper angle, 25° IIRC, & that doesn't suffer with the same problem.
All were originally taped & capped but it only took 3 or 4 years for weathering & deterioration to start becoming noticeable.

 

[niall Y]

My shed/workshop, a concrete sectional garage also has a twinwall roof at a steeper angle, 25° IIRC, & that doesn't suffer with the same problem.

I think you have a point there regarding the angle of slope. There is a polycarbonate roof on our conservatory - not twinwall/triplewall, but a beefier system with enclosed joists. This has had a few insects get inside but no algae/moss.

 

[Lons]

Just for clarification I stocked and sold multiwall polycarbonate from my branch of a national plastics distribution company. This was the earlier days, 1980s when it was starting to take off big time for conservatories and garden centre roofs especially. We distributed industry leading GE Plastics product based on Lexan resin.

The structure of multiwall poly while being extremely strong for it's weight allowing wider span and other benefits over glass also made it subject to the issues being mentioned here. Low pitch angle, weather degradation to tape and thermal movement means it's virtually impossible to stop discolouration, abrasion and algae ingress, also as polycarbonate can be degraded by harsh cleaner and chemicals the issue was difficult to resolve. The recommended (at the time) practice of solid tape at the top which is always covered and breather tape at the bottom covered by F profile to allow ventilation could never keep out moisture and algae, it was there to prevent dust and more importantly reduce heavy moisture which gives a "steaming up" appearance by increasing ventilation. I actually used breather tape top and bottom on mine because it was all I had and it's been ok.

If asked at the time which was rare I'd always suggest that it was prudent to use one of the long, thin round brushes you could get at the time to clean the sections and then renew the tape and silicone the top edge of the F profile but the manufacturers didn't draw attention to that of course. I think 11 years is pretty good btw.

I don't know if the brushes are still around, there were even a few companies at that time who offered cleaning services.

So..............
That's the long answer based on my knowledge and experience of years ago and practices have most probably changed.
The short answer is Yes, it's something that's inevitable IMO.

EDIT

Just as an afterthought, I've regularly used diluted IPA to clean the surface of solid polycarbonate without any obvious issues and it wouldn't be difficult to securely fix a scrap of cloth to a length of dowel soaked in IPA to clean the flutes. Possibly worth a trial also on some scrap poly to see if Wet and Forget liquid removes the algae, it works for me around the house and garden. There are cheaper brands around.

 

[jonw1664]

Just for clarification I stocked and sold multiwall polycarbonate from my branch of a national plastics distribution company. This was the earlier days, 1980s when it was starting to take off big time for conservatories and garden centre roofs especially. We distributed industry leading GE Plastics product based on Lexan resin.

The structure of multiwall poly while being extremely strong for it's weight allowing wider span and other benefits over glass also made it subject to the issues being mentioned here. Low pitch angle, weather degradation to tape and thermal movement means it's virtually impossible to stop discolouration, abrasion and algae ingress, also as polycarbonate can be degraded by harsh cleaner and chemicals the issue was difficult to resolve. The recommended (at the time) practice of solid tape at the top which is always covered and breather tape at the bottom covered by F profile to allow ventilation could never keep out moisture and algae, it was there to prevent dust and more importantly reduce heavy moisture which gives a "steaming up" appearance by increasing ventilation. I actually used breather tape top and bottom on mine because it was all I had and it's been ok.

If asked at the time which was rare I'd always suggest that it was prudent to use one of the long, thin round brushes you could get at the time to clean the sections and then renew the tape and silicone the top edge of the F profile but the manufacturers didn't draw attention to that of course. I think 11 years is pretty good btw.

I don't know if the brushes are still around, there were even a few companies at that time who offered cleaning services.

So..............
That's the long answer based on my knowledge and experience of years ago and practices have most probably changed.
The short answer is Yes, it's something that's inevitable IMO.

EDIT

Just as an afterthought, I've regularly used diluted IPA to clean the surface of solid polycarbonate without any obvious issues and it wouldn't be difficult to securely fix a scrap of cloth to a length of dowel soaked in IPA to clean the flutes. Possibly worth a trial also on some scrap poly to see if Wet and Forget liquid removes the algae, it works for me around the house and garden. There are cheaper brands around.

IPA??? Beer?

 

[Richard_C]

Bottle brush ?

 

[MorrisWoodman12]

IPA - Isopropyl Alcohol - a (mild) solvent fairly readily available online and possibly in store though I've never looked for it or noticed it.

IPA: Also available as beer but that only dissolves your brains.
BRAINS: Another brand of beer brewed in Cardiff. Brains Dark is possibly my favourite beer.
DARK: Where you retreat to after too much of any of the above.

 

[Lons]

I use IPA ( rubbing alcohol ) very regularly, usually diluted. It's reasonably cheap if you buy on line, lasts a long time and excellent for general cleaning and grease removal around the workshop also cleans the 3D printer table rather well. It also dries very quickly.

Haven't tried IPA beer for that but maybe worth a go.