Green Building Forum - Overlaying roofs Sat, 02 May 2026 16:20:08 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123385#Comment_123385 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123385#Comment_123385 Mon, 21 Nov 2011 13:56:12 +0000 tony
They are using nice insulated laminates steel profile sheets

But on top of the existing uninsulated profiled sheeting

This leaves an air gap between the new and existing 80% of the area

This is a winter cooking system making the insulation of very little value -- anyone else seen this going on?]]> Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123440#Comment_123440 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123440#Comment_123440 Mon, 21 Nov 2011 21:27:55 +0000 Jeff B Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123459#Comment_123459 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123459#Comment_123459 Mon, 21 Nov 2011 22:34:18 +0000 CWatters Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123463#Comment_123463 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123463#Comment_123463 Mon, 21 Nov 2011 23:08:26 +0000 Timber
I think you are right Tony, similar to adding a warm flat roof, and not sealing the joist voids, as per the thread on here.]]> Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123464#Comment_123464 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123464#Comment_123464 Mon, 21 Nov 2011 23:26:55 +0000 tony
The undersides of the new sheets are flat and the top of the old are standing seam/ profiled.]]> Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123595#Comment_123595 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123595#Comment_123595 Wed, 23 Nov 2011 09:07:55 +0000 Jonti ]]> Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123603#Comment_123603 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123603#Comment_123603 Wed, 23 Nov 2011 09:50:14 +0000 joe90 Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123615#Comment_123615 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123615#Comment_123615 Wed, 23 Nov 2011 11:02:16 +0000 CWatters Posted By: Timber^ All air voids will allow some convection of air, and this is likely to move air from warm to cold areas.

If the ends were sealed properly an extra air gap could only improve insulation over one without. eg An air gap never has a negative thermal resistance.


Posted By: tonyThere are full length gaps eaves to ridge with no sealing anywhere between the old and new The undersides of the new sheets are flat and the top of the old are standing seam/ profiled.


Perhaps they plan to seal the edges later? Otherwise I agree it doesn't make much sense.]]> Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123643#Comment_123643 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123643#Comment_123643 Wed, 23 Nov 2011 13:25:03 +0000 tony Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123730#Comment_123730 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123730#Comment_123730 Thu, 24 Nov 2011 09:23:20 +0000 Timber
If it were me, I would lay dense mineral wool batts between the profiled lower roof, before the upper roof is installed and still seal the edges of the voids.]]> Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123746#Comment_123746 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123746#Comment_123746 Thu, 24 Nov 2011 09:59:24 +0000 Ben1974 Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123829#Comment_123829 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123829#Comment_123829 Thu, 24 Nov 2011 16:31:30 +0000 Peter_in_Hungary
Is it for insulation or as a soft filler to prevent the old and new sheets interfering with each other and cracking as they are screwed together?]]> Overlaying roofs https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123850#Comment_123850 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8144&Focus=123850#Comment_123850 Thu, 24 Nov 2011 17:53:53 +0000 Ben1974
Some of the old roof is pink from all the coloured sugar dust that is blown out of the top. If you wanted to live near a factory you couldn't choose a better one than a sweet factory. The smell isn't overpowering apart from along the canal tow path near some of the extractors. The air there is hot and sickly sweet. I go running sometimes, if that's the last bit of a route and you're hanging out it makes you want to throw up.]]>