Tue, 19 May 2026 16:46:12 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304924#Comment_304924 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304924#Comment_304924 Mon, 15 Jan 2024 14:36:02 +0000 Rex
Just asking because I am interested.

When a neighbour built their SIP house, they installed a treated timer patio decking at the back. Of course, all the decking is screwed to the under structure and looked good. But over the years, as with most externally used UK construction 'rubbish' timber, the unseen structure has rotted and as I write, they are having it all replaced.

My rhetorical question is, if installing timber decking, what is the best way to ensure that it lasts longer than 10-15 years? Or is it something that one has to bit the bullet and replace every X years?

Thanks and toodle pip]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304929#Comment_304929 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304929#Comment_304929 Mon, 15 Jan 2024 16:42:43 +0000 djh

In general use treated timber outdoors and keep it off the ground. So maybe use metal for the underpinnings?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304938#Comment_304938 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304938#Comment_304938 Mon, 15 Jan 2024 22:05:10 +0000 Jonti https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304946#Comment_304946 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304946#Comment_304946 Tue, 16 Jan 2024 10:57:36 +0000 Simon Still Posted By: RexWhat ho one and all,
Of course, all the decking is screwed to the under structure and looked good. But over the years, as with most externally used UK construction 'rubbish' timber, the unseen structure has rotted and as I write, they are having it all replaced.


What did the sub structure sit on? The one on our flat roof (composite decking on top) sits on plastic feet that hold it a good distance above the roof surface. When we were installing I was still concerned that the understructure wouldn't last as long as the decking itself.

I didn't come across it when we built ours but this place now sells composite joists and tape you can put on the top surface of wooden joists
https://www.edecks.co.uk/]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304950#Comment_304950 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304950#Comment_304950 Tue, 16 Jan 2024 12:51:47 +0000 philedge https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304952#Comment_304952 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304952#Comment_304952 Tue, 16 Jan 2024 13:22:33 +0000 Rex
I find the 4x4 posts that support our wisteria, rot and need replacing after about 10-12 years.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304972#Comment_304972 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304972#Comment_304972 Wed, 17 Jan 2024 12:00:09 +0000 LF
About to put some stone down after 25 years of decking which lasted well.
Rat/s have been a slight issue recently, a lot of neighbours feed birds and they get into sheds where the feed is stored. It is also quite slippy for winter months. Would build in bait stations if doing again.

My decking is at end life now after 25 years probably more luck than judgement - simple redwood 20mm x 100 mm thick pressure treated but not stained. It was refurbed and treated once about 6 years ago.
Frames of 3x3 softwood treated posts sitting on breeze blocks and a bit of dampproof - have never rotted. Treat any cut ends with preserver. Rot on planks mainly around nails that were not treated.
Coated screws were used mainly and did not have same effect - so perhaps stopped water pooling under the wood as it held them tighter to frame ?

I am about to take out some 3x3 posts that were put in 25 years ago and are still rot free.
They were a swing an shelter at various times. Not special timber just treated soft from wickes.
Treat any cut ends with preserver.
I coated the timbers in bitumen underground, I am pretty sure they were wrapped in plastic too- advice from my Dad! Make sure any concrete slopes away from interface point on the post too.
Quite high water table - clay about 18 inches down.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304979#Comment_304979 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=304979#Comment_304979 Wed, 17 Jan 2024 17:12:04 +0000 Rex https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=305283#Comment_305283 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18067&Focus=305283#Comment_305283 Tue, 13 Feb 2024 17:51:40 +0000 fostertom
Design all timber to drain/ventilate/re-dry, not sit in a puddle, and use douglas fir, larch or other semi-durable-grade species. No 'treatment'. Should last forever then.]]>