Green Building Forum - Glass or solid polycarb for verandah roof Tue, 19 Dec 2023 06:47:01 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278149#Comment_278149 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278149#Comment_278149 Tue, 21 Jan 2020 11:59:06 +0000 bardo Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278151#Comment_278151 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278151#Comment_278151 Tue, 21 Jan 2020 12:32:52 +0000 djh

Clear polycarbonate is very strong and unlikely to break, but it will get scratch marks. It's possible to get 'abrasion resistant' coatings but I don't know anything about them. The same goes for acrylic sheet but that generally has better weather resistance.

edit: what kind of a slope does the verandah have? It's not clear in the photo.]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278152#Comment_278152 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278152#Comment_278152 Tue, 21 Jan 2020 12:35:22 +0000 bardo Posted By: djhThe house looks good:bigsmile:" alt=":bigsmile:" src="http:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" >

Clear polycarbonate is very strong and unlikely to break, but it will get scratch marks. It's possible to get 'abrasion resistant' coatings but I don't know anything about them. The same goes for acrylic sheet but that generally has better weather resistance.

Thanks DJH.]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278158#Comment_278158 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278158#Comment_278158 Tue, 21 Jan 2020 14:32:25 +0000 ealingbadger
Acrylic cracks very easily. I wouldn't even consider this material personally. it can be surprising what birds will carry aloft and then decide to drop from height. We frequently get bits of detritus that birds have picked up from the nearby garage business turning up on our alleyway roof after they decide that they are too heavy to continue on with.

All plastics scratch VERY easily. Even if you take care to use non-abrasive cleaning materials there is always some kind of grit hanging about so it will be very difficult to avoid it getting scratched up over time.

You mention 6mm thick solid polycarbonate. Be aware that this is likely to sag eventually.

I have personal very good experience of the multilayer polycarbonate product. I have approximately 15 sq. m. of the 1,000mm wide triple layer 'Ariel Clear' product installed in 1m x 1.5m sections with side edge support only and it is stilling showing no sign whatsoever of sagging since installation in 1992.

I got mine from B&Q, although I notice that they do not appear to carry the 1 metre Ariel triple layer product any more (well, it is well over a quarter of a century ago now from when I bought it! :bigsmile:):

https://www.google.com/search?q=polycarbonate+roofing+sheets

I have never attempted to clean it (access restrictions make this impossible anyway, as it in-fills over an alleyway between our house and the next property) but my experience tells me that it is a racing certainty that it would get scratched if I tried.

The only downside to this is that after more than a quarter of a century lichen colonies have slowly established themselves and the lean-to (as we refer to it) is slowly but surely becoming dimmer over time. But then this is simply a utility and access area through to the rear of the property for us so this does not bother us too much. it certainly would if it was a conservatory or a verandah. And of course glass that went uncleaned for that length of time would suffer similarly of course. interestingly, we do not get the dirty streaks that uncleaned glass often suffers from. Just the (very very) slowly growing lichen colonies.

The impact resistance of this material is truly impressive BTW. Mine has survived at least two corner on impacts over the years from concrete roof tiles falling over 10 metres off the adjacent roof with nothing more than a very minor dent mark left at the impact site.

Despite the above eulogy in praise of polycarbonate my recommendation would be to go for glass - mostly purely and simply because of the ease with which polycarbonate scratches when being cleaned, but also because solid material sags and also, finally, because glass will always look just that bit classier.

I would certainly use polycarbonate again in the right context, just not perhaps if I had a feature verandah such as yours.]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278159#Comment_278159 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278159#Comment_278159 Tue, 21 Jan 2020 14:44:30 +0000 bardo Posted By: ealingbadgerI agree with DJH with regard to the strength of polycarbonate .

Acrylic cracks very easily. I wouldn't even consider this material personally. it can be surprising what birds will carry aloft and then decide to drop from height. We frequently get bits of detritus that birds have picked up from the nearby garage business turning up on our alleyway roof after they decide that they are too heavy to continue on with.

All plastics scratch VERY easily. Even if you take care to use non-abrasive cleaning materials there is always some kind of grit hanging about so it will be very difficult to avoid it getting scratched up over time.

You mention 6mm thick solid polycarbonate. Be aware that this is likely to sag eventually.

I have personal very good experience of the multilayer polycarbonate product. I have approximately 15 sq. m. of the 1,000mm wide triple layer 'Ariel Clear' product installed in 1m x 1.5m sections with side edge support only and it is stilling showing no sign whatsoever of sagging since installation in 1992.

I got mine from B&Q, although I notice that they do not appear to carry the 1 metre Ariel triple layer product any more (well, it is well over a quarter of a century ago now from when I bought it!:bigsmile:" alt=":bigsmile:" src="http:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" >):

https://www.google.com/search?q=polycarbonate+roofing+sheets

I have never attempted to clean it (access restrictions make this impossible anyway, as it in-fills over an alleyway between our house and the next property) but my experience tells me that it is a racing certainty that it would get scratched if I tried.

The only downside to this is that after more than a quarter of a century lichen colonies have slowly established themselves and the lean-to (as we refer to it) is slowly but surely becoming dimmer over time. But then this is simply a utility and access area through to the rear of the property for us so this does not bother us too much. it certainly would if it was a conservatory or a verandah. And of course glass that went uncleaned for that length of time would suffer similarly of course. interestingly, we do not get the dirty streaks that uncleaned glass often suffers from. Just the (very very) slowly growing lichen colonies.

The impact resistance of this material is truly impressive BTW. Mine has survived at least two corner on impacts over the years from concrete roof tiles falling over 10 metres off the adjacent roof with nothing more than a very minor dent mark left at the impact site.

Despite the above eulogy in praise of polycarbonate my recommendation would be to go for glass - mostly purely and simply because of the ease with which polycarbonate scratches when being cleaned, but also because solid material sags and also, finally, because glass will always look just that bit classier.

I would certainly use polycarbonate again in the right context, just not perhaps if I had a feature verandah such as yours.

Ealingbadger. You've helped confirm my concerns about polycarb. Glass seems the way to go. Cheers!]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278160#Comment_278160 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278160#Comment_278160 Tue, 21 Jan 2020 14:47:56 +0000 bardo edit: what kind of a slope does the verandah have? It's not clear in the photo.

Approx 12%. The joist centres are 400mm apart and the glazing panels need to be 2675mm long. I was planning to clamp each of the panels to the joists using glazing bars. With glass and bars it all starts to get pretty pricey though the alternatives don't seem to be up to the job.
]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278163#Comment_278163 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278163#Comment_278163 Tue, 21 Jan 2020 17:07:38 +0000 fostertom Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278165#Comment_278165 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278165#Comment_278165 Tue, 21 Jan 2020 17:49:12 +0000 Simon Still Posted By: fostertomYou can get Pilks self cleaning glass, at a price - the coating uses natural UV to catalyse organic deposits breakdown so they wash away.

Needs a decent fall to work well - we were advised our roof glazing didn't have enough.

" It can be installed vertically or at an angle of 10 degrees or more, although most efficient at an angle of 30 degrees." based on a quick google]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278170#Comment_278170 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278170#Comment_278170 Wed, 22 Jan 2020 08:05:05 +0000 GreenPaddy Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278183#Comment_278183 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278183#Comment_278183 Wed, 22 Jan 2020 13:04:37 +0000 revor
I spent ages looking for suitable bars and eventually bought from here.

https://www.patent-glazing.com/index.html

The website has load of information and I had extremely good service from them. Part of my consignment was damaged by the carrier and they sent one of their employees in the MD's car to replace the items. They are only a small company and I was very impressed by how everyone I dealt with would take ownership of the solution to the query.

What size are your rafters, glazing bars are often wider than the nominal 2"]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278199#Comment_278199 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278199#Comment_278199 Thu, 23 Jan 2020 09:45:00 +0000 bardo Posted By: revorI have a veranda and conservatory roof done in glass. It is double glazed. I have used triple layer polycarbonate on a green house roof in the past and it discoloured, also does not let as much light through as glass. If you price up double glazed panels v's single pane there won't be much difference as you will probably end up with 2 x 4mm in DG and 6 mm in single plus the glazing suppliers are all geared up to do DG. The roofing bars are also likely to be designed for DG and if you put in a single pane you will be paying extra for spacer bars to make up the thickness.

I spent ages looking for suitable bars and eventually bought from here.

https://www.patent-glazing.com/index.html" rel="nofollow" >https://www.patent-glazing.com/index.html

The website has load of information and I had extremely good service from them. Part of my consignment was damaged by the carrier and they sent one of their employees in the MD's car to replace the items. They are only a small company and I was very impressed by how everyone I dealt with would take ownership of the solution to the query.

What size are your rafters, glazing bars are often wider than the nominal 2"

Thanks Revor. Really helpful. I shall follow up...]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278717#Comment_278717 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278717#Comment_278717 Fri, 07 Feb 2020 19:51:22 +0000 ealingbadger Posted By: GreenPaddyAFAIK glass will also sag, so fall is just as important to avoid ponding.

Yes, but that is being a little over-pedantic for the purposes of this discussion.

To all intents and purposes glass may be considered no-sag in this context.]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278775#Comment_278775 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278775#Comment_278775 Mon, 10 Feb 2020 01:53:17 +0000 Mike1
It's not just a matter of providing weather protection. As you may well already know, under the CDM Regulations there is a legal obligation to eliminate, reduce, or control foreseeable risks in the design, including providing safe access for maintenance and repair. And from the photo it looks as though the verandah is 'in the way of' maintaining the main roof, so safe access would need to be considered.

See also
https://www.housingtoday.co.uk/cpd/cpd-4-2019-performance-characteristics-of-glazing-in-rooflights-/5099832.article
https://selfbuildportal.org.uk/healthandsafety/]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278815#Comment_278815 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278815#Comment_278815 Wed, 12 Feb 2020 08:15:02 +0000 GreenPaddy Posted By: ealingbadger
Posted By: GreenPaddyAFAIK glass will also sag, so fall is just as important to avoid ponding.


Yes, but that is being a little over-pedantic for the purposes of this discussion.

To all intents and purposes glass may be considered no-sag in this context.

Thanks for that update. I guess I needn't have worried about the 1200m2 of glazed roof we installed a on a previous project, and the suppliers stressing the importance of sag on edge supported glazing. And the chap on a recent thread whose DG panels had a considerable glass centre sag, causing cold bridging mid pane.

Pedantry has it's place, but usually only valued in hindsight, when something's gone tits-up :bigsmile:]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278849#Comment_278849 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278849#Comment_278849 Fri, 14 Feb 2020 20:42:37 +0000 bardo Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278856#Comment_278856 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278856#Comment_278856 Sat, 15 Feb 2020 11:45:09 +0000 revor
Exp tape does not like being in a pool of water and from my painful experience some of what is on the market does not match up to the claims they make for it, particularly it's resistance to driving rain. Before you commit yourself to the method you propose I would build a trial rig and experiment with that.

Have you costed the job the tape is very expensive you would be better routing a groove in the rafters and the timber capping and using a proprietary EPDM gasket both sides of the glazing.

But bottom line is aluminium bars and capping.

Good luck]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278857#Comment_278857 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278857#Comment_278857 Sat, 15 Feb 2020 12:21:07 +0000 djh https://woodforgood.com/news-and-views/2017/06/29/sustainably-procuring-tropical-hardwood/]]> Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278858#Comment_278858 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=278858#Comment_278858 Sat, 15 Feb 2020 12:57:41 +0000 bardo Posted By: revorOak will be problematic long term. It is too open grained and whatever finish you put on it will not last. You will be up and down like a YO YO cleaning and recoating. Vertical surfaces are easily ruined yours in an almost horizontal position will look a mess in no time at all. If you must use timber go for a closer grained timber like Sapele or Iroko. They are also cheaper.They tend to have little or no knots and you will need to buy premium grade oak for it to be knot free. The expansion and contraction of the timber will cause no ends of issues with leaks regardless of using expanding foam tape.

Exp tape does not like being in a pool of water and from my painful experience some of what is on the market does not match up to the claims they make for it, particularly it's resistance to driving rain. Before you commit yourself to the method you propose I would build a trial rig and experiment with that.

Have you costed the job the tape is very expensive you would be better routing a groove in the rafters and the timber capping and using a proprietary EPDM gasket both sides of the glazing.

But bottom line is aluminium bars and capping.

Good luck

Thanks revor. That's really helpful experience shared. It has given me pause to rethink.]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=279080#Comment_279080 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=279080#Comment_279080 Tue, 25 Feb 2020 13:13:08 +0000 ealingbadger Posted By: GreenPaddy
Posted By: ealingbadger
Posted By: GreenPaddyAFAIK glass will also sag, so fall is just as important to avoid ponding.


Yes, but that is being a little over-pedantic for the purposes of this discussion.

To all intents and purposes glass may be considered no-sag in this context.


Thanks for that update. I guess I needn't have worried about the 1200m2 of glazed roof we installed a on a previous project, and the suppliers stressing the importance of sag on edge supported glazing. And the chap on a recent thread whose DG panels had a considerable glass centre sag, causing cold bridging mid pane.

Pedantry has it's place, but usually only valued in hindsight, when something's gone tits-uphttp:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" alt=":bigsmile:" title=":bigsmile:" >

I stand corrected.

Always happy to learn, so thank you.

Though it does feel counter-intuitive based on my own admittedly entirely anecdotal observations.

Nevertheless, I am grateful for the new insight.

And I happen to believe that pedantry is a much undervalued skill that could do with being applied a great deal more widely. :bigsmile:]]>
Glass or solid polycarb for verandah roof http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=279081#Comment_279081 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16409&Focus=279081#Comment_279081 Tue, 25 Feb 2020 13:19:19 +0000 ealingbadger Posted By: bardo
Posted By: revorOak will be problematic long term. It is too open grained and whatever finish you put on it will not last. You will be up and down like a YO YO cleaning and recoating. Vertical surfaces are easily ruined yours in an almost horizontal position will look a mess in no time at all. If you must use timber go for a closer grained timber like Sapele or Iroko. They are also cheaper.They tend to have little or no knots and you will need to buy premium grade oak for it to be knot free. The expansion and contraction of the timber will cause no ends of issues with leaks regardless of using expanding foam tape.

Exp tape does not like being in a pool of water and from my painful experience some of what is on the market does not match up to the claims they make for it, particularly it's resistance to driving rain. Before you commit yourself to the method you propose I would build a trial rig and experiment with that.

Have you costed the job the tape is very expensive you would be better routing a groove in the rafters and the timber capping and using a proprietary EPDM gasket both sides of the glazing.

But bottom line is aluminium bars and capping.

Good luck


Thanks revor. That's really helpful experience shared. It has given me pause to rethink.

+1 for what Revor said I'm afraid.

I love oak, but he is dead right.

In fact, I have an obsessive love affair with all timber, but I simply would not contemplate using it in your context.

Also -with regard to the suggestion that Sapele or Iroko will be better - yes, they will, but still nowhere near better enough to make any sense using them either.]]>