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Thread: Boat Shed Loft

  1. #1
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    Default Boat Shed Loft

    I have a some basic construction questions and am fishing for ideas to add a loft in a boat shed. One of the reasons we bought this old place was that it had a 40x16 boat shed, that it is in Blue Hill was key. I have a B-in-law who loves construction projects, and unlike me, is quite good at it, having designed and built one of the best B&B's in MO. He also likes visiting us and wants a project, so we decided on adding a loft. He's not much with emails so I need to get the materials ready before his visit in August.




    Thinking the loft should be about 22' long and 10' above the floor, that would give enough room to loft in the loft a 20' boat and then have light storage. I don't need a lot of head room in the loft as I'm vertically challenged, now down to 5'8".

    A question about mounting the joists. The span table says 2x10x16 on 16' centers should work. Does it make a difference if they are hung on hangers or set on a ledger?

    Also would sistering(?) the uprights be advised?

    Lots more to think about before August.

    Thanks,
    Steve B
    TraditionalSmallCraft.com
    Rivus 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  2. #2
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    Default Re: Boat Shed Loft

    Hangers or a ledge make no odds structurally, use whatever suits the existing structure. Can't advise on doubling the uprights.
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: Boat Shed Loft

    How tall is the existing ceiling? My initial take was to suggest adding joists and popping the roof up to keep the full height of your existing space, but that is not a project you can sneak past the neighbors or local build inspector very easily.

    Looks to me like you will have to lose a number of the existing joists, replacing them with collar ties so the walls don't bow out, though the new floor/ceiling of the loft space should help with that too. You will want to make sure the rafters are well secured to the top of the wall, there are brackets for this if the rafters are the usual 1.5" thick.
    Steve

    Boats, like whiskey, are all good.
    R.D Culler

  4. #4
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    Default Re: Boat Shed Loft

    I have about 18' vertically to play with. The existing joists will go, replaced with some number of collar ties.

    Neither neighbors or building inspectors would be an issue here, but I should have plenty of existing space to work with as is. I just need enough of a plan and materials to keep him busy.
    Steve B
    TraditionalSmallCraft.com
    Rivus 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  5. #5
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    Default Re: Boat Shed Loft

    Wonderful boat shed! A loft will make it perfect.

    I would attach ledger 2 x 10 ledger boards to each side with (2) 3-5/8" Ledgerlok bolts (at Home Depot, runs in with an impact driver so no drilling or socket wrenches) and install the joists with joist hangers. Like Steve said, you can remove the rafter ties at the base of the rafters and replace them with collar ties located 1/3 of the way down from the ridge board. Hurricane ties / twist straps/ rafter ties along with the toe-nailing the joist hangers require will take care of all the outward forces. Last thing, for the loft floor I'd recommend Advantech subfloor. It has a 50 year warranty against swelling from moisture.

    Mike

  6. #6
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    Default Re: Boat Shed Loft

    Quote Originally Posted by SBrookman View Post
    I have about 18' vertically to play with. The existing joists will go, replaced with some number of collar ties.

    Neither neighbors or building inspectors would be an issue here, but I should have plenty of existing space to work with as is. I just need enough of a plan and materials to keep him busy.
    Steve, are you saying that it is 18 feet to the top plate of the walls?
    Meaning you will have an 8 foot knee-wall to the roof rafters if you put the loft floor at 10 feet?
    Or is there 18 feet to the ridge?

  7. #7
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    Default Re: Boat Shed Loft

    Quote Originally Posted by jackster View Post
    Steve, are you saying that it is 18 feet to the top plate of the walls?
    Meaning you will have an 8 foot knee-wall to the roof rafters if you put the loft floor at 10 feet?
    Or is there 18 feet to the ridge?
    18' to the ridge.
    Steve B
    TraditionalSmallCraft.com
    Rivus 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  8. #8
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    Default Re: Boat Shed Loft

    Quote Originally Posted by Mike J View Post
    Wonderful boat shed! A loft will make it perfect.

    I would attach ledger 2 x 10 ledger boards to each side with (2) 3-5/8" Ledgerlok bolts (at Home Depot, runs in with an impact driver so no drilling or socket wrenches) and install the joists with joist hangers. Like Steve said, you can remove the rafter ties at the base of the rafters and replace them with collar ties located 1/3 of the way down from the ridge board. Hurricane ties / twist straps/ rafter ties along with the toe-nailing the joist hangers require will take care of all the outward forces. Last thing, for the loft floor I'd recommend Advantech subfloor. It has a 50 year warranty against swelling from moisture.

    Mike
    Mike, thanks, I discovered those Ledgerlock bolts last week when I was building a lean-to for boat lumber. Neat and save time.

    My wife's family is scattered all around the STL area. Have you ever been to Hermann? That's where the B&B is. Neat little German village.
    Steve B
    TraditionalSmallCraft.com
    Rivus 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  9. #9
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    Default Re: Boat Shed Loft

    Steve,
    Looks like you probably have a 10/12 roof pitch which would mean 6'8" or so above the top plate. If you have 18' to the ridge, that would mean 11'4" wall height? Those are tall walls!
    What Mike J suggest seems good.
    One note, if my back-of-an-envelope math is close, then collar ties 1/3rd the way down the rafters (3'3") would give you around 6' of headroom in the loft.
    Another note, collar ties hold the top of the rafters together and are a bit redundant in common construction.
    Good luck with your build.

  10. #10
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    Default Re: Boat Shed Loft

    Collar ties are only redundant when there are ceiling joists to take the thrust load at the bottom end of the rafters. The rafters will want to push the walls outwards when there is a snow load on the roof, so the loft floor joists will have to hold the walls together.

    It looks like a 12' ceiling, maybe a little more. a 10 foot ceiling puts the floor joists 2' below the point where the rafters hit the top plates on the wall. That will put a bit of a bending load on the upper ends of the studs, but that shouldn't bother a 2x6. It may bother a building inspector, but everything unconventional bothers them.

    As I read the question, and interpret the picture, you asked if the joists should sit on top of the ledger or should be attached to the face of the ledger with joist hangars.
    Setting on top of the ledger board will make it a lot easier to build. If the joists sit on top, all the ledger board does is hold the joists up until you attach them to the studs, and all of the vertical load is taken by the ledgerlock bolts, a 2x4 is plenty, not to mention easier to lift. It looks like you have 2x6 studs, so I can't see any need to double.

    The joists need to be tied laterally to the studs to take the thrust load from the roof. It would be convenient if the joists lapped far enough over the studs to nail or screw them together as in this picture from here. If the inside width is 16', you will need to tie the joists to the walls with tie plates because cutting 18' boards down to 16' 10" so you can face nail them to the studs is a pain in the NSFW. AFAIK the joist hangers support vertical loads, but are not intended for lateral loads, so the tie plates and the ledgers will do a better job. Similar construction questions.
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  11. #11
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    Default Re: Boat Shed Loft

    Could you lap the new joists past the existing studs with a jack stud added underneath the joist?
    That would double up the "column", support the joists directly from the foundation, and function as a collar tie.

  12. #12
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    Default Re: Boat Shed Loft

    I think there is a bit of "term differential" here between "rafter tie" and "collar tie (beam)".

    https://www.nachi.org/collar-rafter-ties.htm
    And, I would drill for the Ledgerlok screws. Both the ledger and the studs.
    Last edited by jackster; 06-24-2017 at 04:52 AM.

  13. #13
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    Default Re: Boat Shed Loft

    Thanks guys, here's the image with the measurements of what I'm planning.
    '
    It is 16' wide wall to wall so I should be able to lag a 16' 2x10 to the existing studs.
    Steve B
    TraditionalSmallCraft.com
    Rivus 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  14. #14
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    Default Re: Boat Shed Loft

    I wish I knew how to do that with my computer! guess I should ask my daughter.

    That 3' knee wall that results is max, in my opinion. Not standard practice.
    The collar tie does not provide spread resistance at the plate.
    However, since the loft only comes out half way (20'?) and you have the gable end tied in, I think it will work for that (8/12?) pitched roof.
    You don't indicate in the drawing, but I think you need the ledger, even with the lags.
    My (free) 2 cents anyway.
    BTW, how are you getting up 10 feet in the air? Stairs take up a LOT of floor space.
    Last edited by jackster; 06-24-2017 at 06:34 AM.

  15. #15
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    Default Re: Boat Shed Loft

    Quote Originally Posted by jackster View Post
    I wish I knew how to do that with my computer! guess I should ask my daughter.

    That 3' knee wall that results is max, in my opinion. Not standard practice.
    The collar tie does not provide spread resistance at the plate.
    However, since the loft only comes out half way (20'?) and you have the gable end tied in, I think it will work for that (8/12?) pitched roof.
    You don't indicate in the drawing, but I think you need the ledger, even with the lags.
    My (free) 2 cents anyway.
    BTW, how are you getting up 10 feet in the air? Stairs take up a LOT of floor space.
    That was a quick draw, yes, planning on a ledger, but of what dimension?
    Still haven't decided on exact size of the loft, but probably 22', just over half.
    If I double a couple of the joists would that be suitable for anchoring hoists? I don't ever anticipate having boats much larger than 20' (2500#)
    How am I getting up 10'? Eventually there will be stairs in the back. For construction, that will be an issue, as maneuvering a 2x10x16 on ladders will be a challenge.

    Since you're just down the peninsula, drop by and have a look whenever you're heading this way.
    Steve B
    TraditionalSmallCraft.com
    Rivus 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  16. #16
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    Default Re: Boat Shed Loft

    For construction you can rent a section or two of pipe staging very inexpensively. You might want to beef up the end joist - what will be the edge of the loft. Maybe a pair of microlams or parralams. Your lumber yard should be able to size that for you. Frame the stairwell/ladder well when you frame the loft floor, it's a pain to do it later. Maybe more of a ship's ladder than an actual staircase.

  17. #17
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    Default Re: Boat Shed Loft

    Here's one I built for a client:




    The 1x treads are let into dados routed into 5/4 x 12 stringers and there is a cap/handhold on the left side.

  18. #18
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    Default Re: Boat Shed Loft


    I can see the loft looking like that. I haven't got to the stair design yet, but I like the simplicity of your steps.

    It looks like you used 2x6 for the ledger and mounted the joists above. That seems the the way to go.

    Renting scaffolding makes sense, especially considering the combined age of the 2 old farts building this will be 136, which is much younger that when Susan's dad helped with the deck, 158 yrs. But that was ground level.
    Steve B
    TraditionalSmallCraft.com
    Rivus 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

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