Treated timber

Discussion in 'Carpenters' Talk' started by John Bunyan, Aug 3, 2022.

  1. John Bunyan

    John Bunyan Active Member

    @Rosso I'll check the price of tanalised shiplap and will definitely consider it.
    So if I battened on top of membrane with say 38x18 tan vertically, is the best way at external corner to maybe double up with some timber vertically, so to speak, so I can run the shiplap into it on both sides? Basically what's the best way to finish shiplap on the external corner?
     
  2. John Bunyan

    John Bunyan Active Member

    A mate told me he knew I guy who had a lock up and put a tv and couch in there. Apparently he sometimes went there when his wife thought he was working.
    I guess sheds can cause relationship problems. ;)
     
    Abbadon2001 likes this.
  3. John Bunyan

    John Bunyan Active Member

    The concrete slab stands up 5 inch so I'm wondering how to finish the detail at bottom. Maybe do stud flush and drop the membrane, OSB, battens and cladding down maybe only 2 inch to avoid rain splash from flags.
     
  4. ramseyman

    ramseyman Screwfix Select

    Yes, drop the membrane below the ffl of the slab and extend the bottom row of shiplap half a board beyond/below it too. Then of course need to avoid future soil build-up. At the corners add an additional batted so the shiplap runs up to it and hence no end grain is visible. Keep us posted on the Pilgrim's progress.....
     
    John Bunyan likes this.
  5. NJ Rider

    NJ Rider Member

    Bit late to the topic but wanted to say I used untreated cls for a deck platform on top of treated sleepers and ended up having to replace most of it after 5 years. That's after I used wood preserver on it. So I wouldn't use anything but pressure treated outside these days. Far cheaper than the time and double cost of replacing it after a few years.
     
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  6. John Bunyan

    John Bunyan Active Member

    @Rosso
    What's the purpose of battening out?
    I'm thinking it's not essential?
    I'm thinking studs, OSB, roof membrane, then feather edge?
     
  7. Rosso

    Rosso Screwfix Select

    Vertical battens allow air to circulate behind the cladding preventing mould and damp. Also any rainwater blown through the cladding can run down rather than rotting out the cladding from the back. Battens are nailed through the tyvek, so where the membrane is punctured, it is covered/sealed by a batten preventing moisture penetration.
    However, you are building a lean-to shed- you don't have to comply with building regs. You can do whatever you like
     
    John Bunyan likes this.
  8. John Bunyan

    John Bunyan Active Member

    @Rosso
    That makes sense to me.
    So, to recap, stud wall, then OSB, then, tyvek or similar, then battens, then final cladding?
     
  9. Rosso

    Rosso Screwfix Select

    Spot on. Mind you, you could put the osb on the inside of your stud walls...structurally it would be the same and it might seem less shed-like inside. The Tyvek (or roof breather membrane) would keep the weather out of the stud walls. The membrane will be protected by the batten and cladding. Are you going to insulate?
     
    Last edited: Aug 11, 2022
    John Bunyan likes this.
  10. John Bunyan

    John Bunyan Active Member

    @Rosso
    Which side the OSB goes is something I'll think about.
    No insulation at this time, possibly in the future.
    If I put OSB on the inside I could just membrane, batten, and feather edge now and board the inside at a later date to keep cost down so that may need what I'll do. I'm using all tanalised 3x2.
    So what's the purpose of the OSB in general and particularly on the outside?
    Just wondering why premanufactered sheds don't have a membrane integrated into the stud walls. Surely it would be much more weather proof.
     
  11. John Bunyan

    John Bunyan Active Member

    @Rosso
    I know you'd probably use tyvek but I'm trying to keep cost down so cromar vent 3 should be ok surely?
    I'll still batten out between membrane and feather edge.
    I've already bought a rubber roof kit so don't need any membrane there.
     
  12. Rosso

    Rosso Screwfix Select

    The osb is there to strengthen the structure and keep it square- stops it buckling. We used to use diagonal bracing.
    Re. Tyvek- the building inspector won't allow roof membrane in walls, and in house walls you really don't want an air-permeable membrane as it makes the insulation less effective, or so I am told.
    Most commercial sheds are pretty rubbish, made with the cheapest materials and methods, so the manufacturer isn't going to add additionals until they have to. Also as the shed walls are usually single panels there would be no way to seal the join, so why bother at all?
     
  13. John Bunyan

    John Bunyan Active Member

    @Rosso
    Fortunately for me, two walls of this shed is brick so I don't need to OSB to keep it square.
    OSB could help stop the walls from twisting though.
    From what I can see, the tyvek is breathable?
    One other question, I thought the membrane goes on horizontally starting at the bottom first and overlapping each row.
    It's just i saw a guy on YouTube putting the membrane on vertically with good overlaps. He didn't batten out but said you could batten out on top of the overlaps. What's your opinion?
     
  14. jimoz

    jimoz Screwfix Select

    Hi Rosso just read this. Not trying to start a row but regularised timber which is often interchanged for cls can be graded. I've got C24 cross battened in my ceiling.
     
  15. Rosso

    Rosso Screwfix Select

    Not rowing, but: They aren't interchangeable, CLS cannot be substituted for C16 or C24 and still comply with spec. CLS is almost always untreated, and either 38x63mm or 38x89mm neither of which are UK standard(HAHA) sizes for regularised timber 45x70mm or 45x95mm being normal. Nor can you mix CLS and std. reg. timber within a structural element without causing yourself difficulties.
    Don't get me wrong, there's nothing wrong with CLS, but using graded timber instead of CLS is a significant upgrade.
     
  16. Cris 11

    Cris 11 Active Member

    Personally I would use granite and limestone for the walls like the great pyramids of Giza they have stood for about 4500 years, plus a reinforced concrete roof with titanium roof trusses.
    Then I would lead line it so after the coming nuclear war when all life on earth has been extinguished at least your paint will be safe from the radiation.

    Then in a few million years time when a new species has evolved your shed will probably be the only sign left of human existence, a future archaeologist may discover it and come to the conclusion.
    Humans where stupid enough to destroy themselves, but they sure knew how to build a shed.
     

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