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How do you flash wood joists against concrete?

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  • #630478

    What is the best way to flash a concrete porch against the wood floor trusses and blocking as shown in the attached pic (area circled in red)? How close to the concrete should the 1/2″ exterior sheathing be on top?

    This is a new home construction. The details for this house must conform to the IRC 2012 standards.

    #630485
    kurt@welkerhomes.com
    Moderator
    Owatonna, MN - Minnesota

    we would use Ice and water shield then cover that with a bent galvanized flashing. Kind of a belt and suspenders approach.

    #630487

    Does the bent metal fold under the concrete or under the sill plate? How far up the wall should the flashing be run? Would an expansion joint be needed between the flashing and the concrete or does the ice and water shield work as an expansion joint (not familiar with that product)? To clarify… The ice and water shield will go on the wood side of the flashing?

    A diagram would be most helpful if anybody could provide one.

    Thank you for the help!!!

    #630491
    ChadM
    Moderator
    Rogers, Ohio

    Here is a quick sketch…The pink line is Ice & Water against the wood, the yellow line is galvanized flashing, and the green is a galvanized z flashing that the OSB would sit on. I would extend the ice & water about 10″ up the wall (above the concrete), and extend the galvanized flashing 6″ up the wall.

    Chad

    A Working Pro since 1993

    Member since 12/07/2013

    #630529
    kurt@welkerhomes.com
    Moderator
    Owatonna, MN - Minnesota

    the IRC requires the flashing to be 6″ above the concrete just like chad says. @chadm good job on the detail. that is exactly how I would do it.

    #630705

    That makes sense to me now. Thank you both very much for the replies!

    #630707
    utopia78
    Pro
    Toronto, ON

    the IRC requires the flashing to be 6″ above the concrete just like chad says. @chadm good job on the detail. that is exactly how I would do it.

    As I move from my limited High Rise restoration work and get more experience on residential systems there is tons for me to learn. Awesome question, replies and diagrams! Gave this a long hard look. thanks

    A Working Pro since 2004

    #631916

    Here is a quick sketch…The pink line is Ice & Water against the wood, the yellow line is galvanized flashing, and the green is a galvanized z flashing that the OSB would sit on. I would extend the ice & water about 10″ up the wall (above the concrete), and extend the galvanized flashing 6″ up the wall.

    Definitely the way to go
    @ChadM what do you think about putting weep web or some way for the water to get out from between the concrete and flashing?

    #640476

    I wonder would it be better to run the sheathing down to the sill plate and run the water shield and metal flashing on the outside of the sheathing but under the house wrap? Would you see any problems doing it that way? I just like the idea of the sheathing tying into the sill plate.

    #640477

    Is this porch covered with a roof of any kind ? .

    Always willing to learn .

    #640483

    yes the trusses extend over and past the porch by 2′

    #640485

    yes the trusses extend over and past the porch by 2′

    Okay so it won’t get direct water hitting it . As Chad posted that’s the way to go . Done thousands of times with no problems . Plus that’s slab will be pitched away from that wall for my protection of the wood behind it

    Always willing to learn .

    #640498

    My reply was a concern of structural nature. I plan on using the ice and water shield. I just think it would be better to put it on the outside of the sheathing so the sheathing can tie into the 2×8 sill plate rather the 2×6 wall plate. The porch is 35′ wide (the house is 55′ wide). Is there anything in the IRC that would prohibit putting the shield and flashing on the outside of the sheathing? Will it cause any other problems with the siding (vinyl)?

    #640499
    utopia78
    Pro
    Toronto, ON

    If I ever had wood in contact with concrete I would think of Henry Blueskin TWF. I dunno probably off topic but thought it it might help someone searching and looking at this thread.

    A Working Pro since 2004

    #640637

    The concrete would still not be in contact with the wood (see new attached pic). I thought the IRC required the sheathing to tie into the sill plate. Is that not the case?

    #640640

    If I ever had wood in contact with concrete I would think of Henry Blueskin TWF. I dunno probably off topic but thought it it might help someone searching and looking at this thread.

    Yeah that blueskin product is awesome for use along Masonary for proper protect between the two surfaces .

    My reply was a concern of structural nature. I plan on using the ice and water shield. I just think it would be better to put it on the outside of the sheathing so the sheathing can tie into the 2×8 sill plate rather the 2×6 wall plate. The porch is 35′ wide (the house is 55′ wide). Is there anything in the IRC that would prohibit putting the shield and flashing on the outside of the sheathing? Will it cause any other problems with the siding (vinyl)?

    Oh okay sorry . I would install the siding over the porch slab not under it another layer of protection .

    Always willing to learn .

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