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Discussion in 'Residential Building Codes' started by Keystone, Mar 6, 2018.

  1. Keystone

    Keystone Sawhorse

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    Over the past year we've had a handful of submittals for decks using engineered beams showing "dry use/service", so the plans rejected and resubmitted identifying "wet use/service" and life carried on. Fast forward to this week, we are seeing numerous roofs over decks also indicating dry use/service. So what is the collective thoughts on a roof structure having engineered beams listed as dry use/service?

    We allow dry use/service so long as its protected from the weather, ceiling or wrapped beams.
     
  2. JCraver

    JCraver Sawhorse

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    I think you answered your own question?.?.?.

    If it's under roof (protected from weather), isn't dry use/service fine?

    Maybe I misunderstood the question?
     
  3. Ty J.

    Ty J. Sawhorse

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    We've taken the approach that all exterior exposed beams are required to be wrapped in siding or painted with an exterior grade paint unless it is an exterior grade beam and calculations were for wet use/service.

    Seems folks take less issue with us requiring paint then the wet use/service beam capacities.
     
    JBI likes this.
  4. Keystone

    Keystone Sawhorse

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    I did answer my own question, looking for input from other how they handle it.
     
  5. Keystone

    Keystone Sawhorse

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    Paint, haven't given that consideration. I'll avoid that if we are able to do so.
     
  6. north star

    north star Sawhorse

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    @ ~ @

    Would rain blowing sideways, or condensation \ high humidity conditions
    be enough factors to require "wet use conditions" for the framing over
    the decks ?.......In some locales that have high humidity, some AHJ's
    require everything outdoors to be pressure treated wood.

    IMO, ...just because there is a roof over the framing does not guarantee
    that high humidity \ blowing rains will not effect the framing.

    Just sayin'...

    @ ~ @
     
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  7. Keystone

    Keystone Sawhorse

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    Well understood and agree. Consensus ruled desicion so I respect it.
     
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  8. steveray

    steveray Sawhorse

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    Does the manufacturers paperwork get any more specific? ICC-ES paperwork?
     
  9. Pcinspector1

    Pcinspector1 Platinum Member

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    Plans for a deck are stamped "wet service" or "dry service"? Are all your decks required to be engineered? or does the plans have engineering from a beam supplier like TJI that say "wet or dry" stamped on them?

    This is posted under residential and most plans I get for decks are on notebook paper and submitted by guys with teeth or a finger missing.:eek:

    Wonder what the cost difference is between "wet or dry" service beams? And then you have to add the cost to cover.

    [QUOTE="Keystone, post: 178550, member: 425"We allow dry use/service so long as its protected from the weather, ceiling or wrapped beams.[/QUOTE]
    I agree with your thinking, paint no so much.
     
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  10. Ty J.

    Ty J. Sawhorse

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    I agree with your thinking, paint no so much.[/QUOTE]

    We, here in Southeast Washington, are a low humidity and mostly dry climate (avg. 225 clear days). How one protects the beams is going to vary on a regional basis dependent upon what the weathering potential is. Go over to the West-side of the state (Portland/Seattle areas) and I would predict that all exterior beams are wet service.
     
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  11. JCraver

    JCraver Sawhorse

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    Ok. Well, here, if it's under a roof and protected from the weather, then I permit the use of non-treated beams/framing members. If it can't get wet (i.e., under an overhang and wrapped with aluminum coil stock, which is ~99% of these around here), then I'm not comfortable requiring "wet service" lumber.
     
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  12. Keystone

    Keystone Sawhorse

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    Not that I've seen but it appears time to dig in and do a better job researching....
     
  13. Keystone

    Keystone Sawhorse

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    No ICC ES report. It's a lumber yard cut sheet with load calculations determining PASS or FAIL.
     
  14. Keystone

    Keystone Sawhorse

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    I agree with your thinking, paint no so much.[/QUOTE]

    No the deck plans are not engineered, limiting circumstances would require a Licensed Design Professional. The beam wet or dry service is from the lumber yard cut sheet determining load calculations. Costs associated of upgrading from dry to wet service are unknown but every single beam that has been changed in service has also increased in dimensions.
     
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  15. Francis Vineyard

    Francis Vineyard Sawhorse

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    Possible!
    See 2015 NDS specifics below for engineered wood.

    Sawn Lumber
    The reference design values for lumber specified herein are applicable to lumber that will be used under dry service conditions such as in most covered structure, where the moisture content in use will be a maximum of 19%, regardless of the moisture content at the time of manufacture. For lumber used under conditions where the moisture content of the wood in service will exceed 19% for an extended period of time, the design values shall be multiplied by the wet service factors,

    Structural Glued Laminated Timber
    Reference design values for dry service conditions shall apply when the moisture content in service is less than 16% as in most covered structures.
    Reference design values for glued laminated timber shall be multiplied by the wet service factors, when the moisture content in service is 16% or greater, as may occur in exterior or submerged construction, or humid environments.

    Structural Composite Lumber
    Reference design values reflect dry service conditions, where the moisture content in service is less than 16%, as in most covered structure. Structural composite lumber shall not be used in higher moisture service conditions unless specifically permitted by the structural composite lumber manufacturer.

    Southern Forest Products Association
    Members that are protected from the weather by roofs or other means but are occasionally subjected to windblown moisture, such as for covered porches, are generally considered dry applications.
     
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  16. steveray

    steveray Sawhorse

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    Most of the engineered lumber has some sort of ICC-ES approval from what I have seen, but like FV said manufacturer specific...
     
  17. Ty J.

    Ty J. Sawhorse

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    So if means and methods will protect the beam from moisture absorption above 16%, then the use of wet service factors is not required. Wrapped or sealed beams (paint or lacquered) would be able to accomplish this in most climates.

    By using a wet service factor, the beams capacity/span is diminished by both the moisture (C sub M value) and the incising factor (if pressure treated).
     
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  18. Phil

    Phil Sawhorse

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  19. fatboy

    fatboy Administrator

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    We require that all members exposed to weather be painted/treated with an appropriate coating at the time of inspection. Snapshot in time, maintenance issue after that.Walk away............. SMH.
     
  20. Mark K

    Mark K Platinum Member

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    What is the code provision requiring painting of wood members?

    For composite members there is a concern that the glue/adhesive will loose strength unless they used a glue that is moisture resistant. Once the right glue is used the concern goes away.

    All wood products have a lower allowable load when the moisture content of the wood is high. In order to know if you have a concern you need to know the design loads. Over time the moisture content of the wood will tend to be the same as the atmosphere. It is not clear how ordinary paint will change this.
     
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