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  1. #1
    Join Date
    Sep 2007
    Posts
    177

    Default Protecting top of beams and joist

    Does anyone have an opinion on what is the proper way to seal and protect the tops of the beams and joists on a deck? I have read that the tops should be painted with something called bitumen and then a shield called Proteckadek on top of that. I assumed the bitumen is some kind of rubber sealant. I searched for Proteckadek and it looks like a rubber sheet with glue on one side?? Sort of looks like what roofers use to seal up the lower portions of a roof. A while back someone told me to put a metal guard on top of the beam...but I don't know how that would work with brackets for holding joists to the beams.

    Thanks in advance for any help given.

    -Walt

  2. #2
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,609

    Default Re: Protecting top of beams and joist

    First, I wouldn't consider building a deck with anything but pressure treated lumber as structural members. The rim joist and posts can be clad with the more decorative wood types if desired.

    I like the rubber membrane products. You're right, they are similar to roofing membrane. Nails driven through it will be sealed, much like simple nail punctures in auto tires.

    Aside from helping against rotting, it also helps to keep the stain or paint from peeling. A joist that is not sealed passes moisture up into the decking lumber fastened to it. If possible, seal/stain the bottom of the decking lumber before fastening it down to the joists.

  3. #3
    Join Date
    Mar 2008
    Location
    nova scotia, canada
    Posts
    1,522

    Default Re: Protecting top of beams and joist

    the protectadeck your talking about is simply grace vycor that comes in 2 1/2" wide rolls so to install on teh top of the joists and beams. 4" or 6" blueskin or vycor will do the same thing you just have to cut the strips down the middle
    fire up the saw and make some dust

  4. #4
    Join Date
    Sep 2007
    Posts
    177

    Default Re: Protecting top of beams and joist

    Is the proteckadek from around the top of the beam....or does is have angled side that deflect the water away from the beam. If it does from around the beam does it use adhesive to stick?

    Regarding the materials for the deck....the beams we are using are replacements for 4x12" beams (20 feet long) that have rotted. These beams are going to be in plain view as we walk under them. I am not crazy about using PT for this application due to splits, etc that one often sees in that material. Would a glulam made of cedar be appropriate for this application? I think the material that is currently there is fir. I am not sure how I can tell what that material is.

    -Walt

  5. #5
    Join Date
    Mar 2008
    Location
    nova scotia, canada
    Posts
    1,522

    Default Re: Protecting top of beams and joist

    if its what i think it is , its simply a heavy duty tape you can cut it with a knife to make it the width you need

    as for deck material, most regions wont accept a 2 ply beam, it has to be 3ply 2x10 or 12. as for the material, pt is stronger than cedar. cedar is a weaker species and very soft.. if you worried about the look of splits. most decks i do get completely clad with azek which is a vinyl composite trim, i clad beams, the deck ribbon along with the stair strigner and risers, it really makes the deck stand out
    fire up the saw and make some dust

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