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  1. #1
    Join Date
    Jun 2004
    Location
    St Louis, Mo for the past 25 years
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    7,490

    Default aluminum and pressure treated lumber

    I know that aluminum and pressure treated lumber are not supposed to be mixed. But I do not know if that means raw aluminum or if painted coil stock can be used with pressure treated lumber. I am asking because I just looked at a couple of doors that a customer wants trimmed out in white coil stock and the trim pieces are pressure treated where it sits on top of the concrete. They were told that wood in contact with concrete needed to be pressure treated.

    My first thought was to apply a flashing tape over the PT wood to help isolate it from the metal. But then I do not know if I have ever heard if the painted metal can contact PT or if they are talking about unpainted metal.

    Seems to me that this is one of those areas that one product that is recommended for use almost contradicts the next step in construction.

    I looked briefly at the past threads on the topic but did not see raw aluminum and PT mentioned specifically as what you needed to watch out for or if it is all aluminum products.

  2. #2
    Join Date
    Feb 2008
    Location
    Northwest Indiana
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    5,576

    Default Re: aluminum and pressure treated lumber

    I looked at the boxes of col I have here, 3 different brands, all painted/coated. One is vinyl/pvc coated. All are labeled not to use in contact with treated lumber.

    Tom
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  3. #3
    Join Date
    Jul 2004
    Location
    Western suburbs of Chicago
    Posts
    5,554

    Default Re: aluminum and pressure treated lumber

    Mark, how about using vinyl coil stock for the capping? Aluminum in direct contact with PT is definitely a no-no.
    Greg

  4. #4
    Join Date
    Jan 2007
    Location
    Essex, MA
    Posts
    789

    Default Re: aluminum and pressure treated lumber

    Vinyl coil or isolate it. PT and Alum is bad.....even painted. Remember not to use aluminum nails too.

    MANY years ago I used painted coil as ledger flashing at my own house. Years later when I had to replace a deck board I noticed the flashing was disintregrating. I replaced it with Vycor and plastic ledger flashing.

    These days all my ledgers get Vycor'd and either plastic or copper ledger flashing.
    http://www.putfile.com/jeffaah/images/107329

  5. #5
    Join Date
    Sep 2005
    Location
    west milford n.j.
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    892

    Default Re: aluminum and pressure treated lumber

    ive only seen a few cases of excessive corosion of aluminum over pt on homes,most commonly on the bottom edges of post that rest on concrete,not saying it not a no-no just saying it probably isn't much of an issue on trim that stays dry
    Tom

  6. #6
    Join Date
    Feb 2008
    Location
    Northwest Indiana
    Posts
    5,576

    Default Re: aluminum and pressure treated lumber

    This is what I use. Make sure you use copper nails. Very easy to hand form.

    http://www.milldirectcopper.com/inde...&products_id=8

    As Jeff indicated, vinyl may be your best bet. Not sure if I would trust a barrier.

    Tom
    Last edited by tjbnwi; 09-08-2010 at 10:33 PM. Reason: spelling
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  7. #7
    Join Date
    Jan 2009
    Location
    Danbury area of western CT
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    4,441

    Default Re: aluminum and pressure treated lumber

    Thanks for that link Tom ;-)

    phil
    It's better to try and fail, than fail to try.

  8. #8
    Join Date
    Feb 2008
    Location
    Northwest Indiana
    Posts
    5,576

    Default Re: aluminum and pressure treated lumber

    You're welcome. Looking forward to more pics of your "rooflet" project.

    Tom
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  9. #9
    Join Date
    Jun 2004
    Location
    Des Moines, Iowa
    Posts
    3,829

    Default Re: aluminum and pressure treated lumber

    Beez

    Here you go

    Aluminum coil painted both sides and 6 years
    Attached Images Attached Images
    Mark Parlee
    BESI(building envelope science institute) Envelope Inspector
    EDI Certified EIFS Inspector/Moisture Analyst/Quality Control/Building Envelope II
    Level one thermagrapher (Snell Training)
    www.thebuildingconsultant.com
    www.parleebuilders.com
    You build to code, code is the minimum to pass this test. Congratulations your grade is a D-

  10. #10
    Join Date
    Jun 2004
    Location
    St Louis, Mo for the past 25 years
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    Default Re: aluminum and pressure treated lumber

    Quote Originally Posted by Mark Parlee View Post
    Beez

    Here you go

    Aluminum coil painted both sides and 6 years
    That is a perfect example of what I am talking about. PT wood used around the concrete/brick is required. Then the folks think you can cover it with metal. Looks what happens. However it is a place where one requirement means something else cannot be used or if it is used trouble will show up later.

    I do find it a bit odd that only the bottom area is bad. Any thoughts on that? Maybe the wood keeps soaking up moisture from being in close contact with the ground?

  11. #11
    Join Date
    Jun 2004
    Location
    Des Moines, Iowa
    Posts
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    Default Re: aluminum and pressure treated lumber

    I believe you my be right that it is a moisture cause

    The one withe overhang has no damage and the one at the gable wall has the deterioration
    Attached Images Attached Images
    Mark Parlee
    BESI(building envelope science institute) Envelope Inspector
    EDI Certified EIFS Inspector/Moisture Analyst/Quality Control/Building Envelope II
    Level one thermagrapher (Snell Training)
    www.thebuildingconsultant.com
    www.parleebuilders.com
    You build to code, code is the minimum to pass this test. Congratulations your grade is a D-

  12. #12
    Join Date
    Sep 2005
    Location
    west milford n.j.
    Posts
    892

    Default Re: aluminum and pressure treated lumber

    thats what i was tryin to tell you guys
    Tom

  13. #13
    Join Date
    Jun 2004
    Location
    Des Moines, Iowa
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    Default Re: aluminum and pressure treated lumber

    Tom

    The biggest problem is that you can't say for sure what trim will stay dry and what won't so it really can be a crap shoot.
    The instructions say not to use aluminum over treated but if you choose to go against the instructions that would be called a construction defect.
    In Iowa you are liable for 15 years on construction defects; 15 years is a long time.
    Currently I am consulting on 108 units of town homes at 100k to 130k ea
    30 units 120k ea
    16 at 400k ea
    4 homes at 1M ea
    damages to the 4 homes alone are around 150k ea
    A lot of different problems all of which could have been avoided by following the manufactures directions for installation.
    I still build homes but I have come to the realization I am only as good as my worst sub and responsible for their work; the contract in my state as the GC is with me and my customer, not my customer an my sub so believe me I do watch my subs. I have to know more about most of their job than they do.
    Mark Parlee
    BESI(building envelope science institute) Envelope Inspector
    EDI Certified EIFS Inspector/Moisture Analyst/Quality Control/Building Envelope II
    Level one thermagrapher (Snell Training)
    www.thebuildingconsultant.com
    www.parleebuilders.com
    You build to code, code is the minimum to pass this test. Congratulations your grade is a D-

  14. #14
    Join Date
    Sep 2005
    Location
    west milford n.j.
    Posts
    892

    Default Re: aluminum and pressure treated lumber

    easy Mark,i agree i don't wrap any pt,i have seen alot of installations too and the point i was trying to get across was the presence of concrete and moisture being the catalyst for corrosion on the aluminum,i can pretty much figure out what trim will be a problem and what won't on any given siding job
    Last edited by tom struble; 09-10-2010 at 06:21 AM.
    Tom

  15. #15
    Join Date
    Jun 2004
    Location
    Des Moines, Iowa
    Posts
    3,829

    Default Re: aluminum and pressure treated lumber

    Tom
    Sorry not trying to come off strong on you but in rereading this morning it could seem that way.
    The problem with this method of communication is you don't get to see my bright smiley face nor I yours.

    We need to integrate skype videos on this board
    Mark Parlee
    BESI(building envelope science institute) Envelope Inspector
    EDI Certified EIFS Inspector/Moisture Analyst/Quality Control/Building Envelope II
    Level one thermagrapher (Snell Training)
    www.thebuildingconsultant.com
    www.parleebuilders.com
    You build to code, code is the minimum to pass this test. Congratulations your grade is a D-

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