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lean-to advice

Discussion in 'In the Garden' started by Hagus72, 6 Jul 2021.

  1. Hagus72

    Hagus72

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    hi all,

    I am new on here so hopefully this is posted in the correct forum.

    I am thinking of building a lean-to (that might turn into a shed at some point). It would come off the side of the house and would be 11' long and 9' wide. I am thinking that i need to bolt a 4x2 to the house to carry the roof.

    The opposite corners would be 3x3 posts. And the joists......rafters would be 3x2.

    Would a 4x2 bolted to the wall be adequate?
    If so how far apart should the retaining bolts be over an 11' stretch?

    I am open to any advice no matter how harsh :D

    (y)
     
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  3. JohnD

    JohnD

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    is this like a car-port?

    I found design info online when "designing" mine

    the polycarbonate supplier had info on timber sizes

    I think I used a 7" joist as a wall ledger, because it was handy at the timberyard

    And mine has 4 3" (fence)posts in steel sockets raised off the ground, bolted down to concrete feet
    there are gallows-like diagonals spreading the load from the long open end, mostly because I think they make it look better. There is an extra post about 6' from one end because I enclosed it as a small store shed from the start. The height matches the curtain-sides of garden gazebos and I fitted screw-eyes as it was a cheap and easy way to provide weather protection. At the time I was hard up and people were always offering gazebo sides cheap or free.

    There were height and size rules I no longer remember

    It needs a gutter and downpipe
     
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  4. sxturbo

    sxturbo

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    4x2 with big 14mm coach screws or wall anchors every 500mm will be fine on the wall.

    I've recently built a 7meter by 3.5 lean-to with polycarbonate flat roof sheet and glazing bars.

    I've got 6" joists running the 3.5meter depth notched into the wall plate.

    This method has been used on 6 builds for friends and family that I've helped with and has still been standing 20+ years later
     
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  5. Mr Chibs

    Mr Chibs

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    I’m just going through this at the moment.

    But I’m preferring glass instead of twin wall... although might consider 6mm polycarbonate but haven’t decided yet.

    I have around 5m length and around 3m span. Glass panels are weighing in at around 31kg each, 3m x 700mm... polycarbonate is half that.

    I had intended to use 6 x 2, or even 4 or 5x2. At around 210kg for the glazing I don’t think the weight is a problem.

    As turbo said, I will use a notched wall plate. Presume you guys Secure the rafter to wall plate with a long screw... I don’t want to use joist hangers.

    (y)
     
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  6. sxturbo

    sxturbo

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    Yes just use a long screw or 2 to hold the joist in the wall plate
     
  7. Hagus72

    Hagus72

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    bloody hell never expected this much response (y) awesome.......i have lean-to envy now

    so.... ok the joists need to be notched into the wall ledger/plate? Are the ledger and plate the same thing? As in the bit i need to bolt to the wall?

    I am going to put a wooden roof on it, would 1/2 inch ply be ok?
     
  8. sxturbo

    sxturbo

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    Yes wall / ledger plate referred to here is same.

    I put 2" notch in the wall plate and 2" notch on the 6" joist then long screw up from the bottom.

    For the other end to the wall plate, 3" notch on the 6" joist, but the beams you will probably want 8x2 and a 3" notch in again so they slot into each other.

    As for the posts, I used 4" posts, notched 8"X2 into the post so the beams sit on the post flush, and used coach screws to hold them in.

    Recommendation is to use deck screws to hold it all together, but use galvanised turbogold (self drilling & cutting) coach screws, no need for pilot holes this way and the screws and bolts should last a minimum of 25 years supposedly.

    For roof 18mm marine ply should be ok, but depends on the spacing of the joists.
     
  9. Hagus72

    Hagus72

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    Brilliant info cheers.

    The spacing of the joists was going to be my next question :)

    So it is 11 foot in length and 9 foot deep..........could i get away with 4x2 joists? If spaced correctly?
     
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  11. sxturbo

    sxturbo

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    Sorry yeah forgot you were only going out 9 feet, 4x2.

    Spacing I'm not sure, but 450 prob be ok
     
  12. Hagus72

    Hagus72

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    OK cheers, been very helpful

    I think i know where to start now. I will draw out a rough sketch and post it, see if it is somewhere near ..........it will not be pretty :eek:
     
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  13. Hagus72

    Hagus72

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    sorry to be a pain.......

    is there anyway i can use 3x2's? for the joists?

    9 foot span/depth. Just find them a bit easier to handle working on my own. Can i put a brace down to centre maybe?
     
  14. Mr Chibs

    Mr Chibs

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    How heavy are the sheets you will be covering the rafters with?

    I think 3x2 will look a bit small, what about 4x2 or 5x2, these won’t be heavy.
     
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  15. scbk

    scbk

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    I'm not an engineer, but you need to think of potential bad weather, heavy winds (tie it together well) or 2ft of snow sat on top of it.
     
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  16. Hagus72

    Hagus72

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    yeah fair do's i was just being lazy. 4x2's with a max of 450mm centres it is then :)

    Whats this OSB board all about? OSB vs PLY? For the roof.
     
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