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I need to replace a header in a 3' rough opening. This is in a load-bearing wall that runs down the middle of the house. There is one floor above the wall. House is 28' wide. Is a 3.5" x 3.5" 1.8E parallam PSL sufficient?

This Weyerhaeuser tech note appears to indicate that this is sufficient but I don't understand what the difference is between the white and green rows. Minimum and recommended? The relevant table is the 2nd to last one, "FLOOR ONE STORY – 100% (SIMPLE SPAN ONLY)." What was in there before is a pair of 2x4s laid flat on top of each other so I'm guessing the 4x4 is stronger.

I am certain that the wall is load-bearing. The ends of all the 2nd floor joists rest on it. The house is old and under-built by today's standards but all the lumber is old-growth douglas fir.

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  • Are you sure it's load-bearing? Two flat 2x4s is a classic non-bearing header.
    – isherwood
    Commented Nov 22 at 19:22
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    @isherwood Reasonably certain. All the joist of the second floor rest on this wall. The house is 70 years old. It's under-built by today's standards but it's made of old-growth douglas fir.
    – aquaticapetheory
    Commented Nov 22 at 19:30
  • We have very good precedent for asking about that, among other recurring themes, on this site.
    – isherwood
    Commented Nov 22 at 21:44

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No. The bare minimum bearing header is a double 2x6 (the 5¼" size for this product). That's even questionable for this span. I'd want to see a double 2x8 or 2x10. It doesn't matter that you have laminated lumber.

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  • so is this article just wrong or is that because it's an outside wall? The 2x8 or 2x10 seems extreme.
    – aquaticapetheory
    Commented Nov 22 at 19:56
  • It may well meet nominal requirements, but in practice you'll never see 2x4 in an exterior wall. This has been true since the 80s, at least.
    – isherwood
    Commented Nov 22 at 19:57
  • I think the use of 2x6s in exterior walls was more for extra insulation than strength.
    – crip659
    Commented Nov 22 at 21:12
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    We're talking about headers, with structural members in an upright orientation. Wall thickness isn't a factor. Load-bearing 2x4 walls had at least double 2x6 headers as far back as my experience goes.
    – isherwood
    Commented Nov 22 at 21:14
  • @isherwood Can you tell what the difference is between the white and green rows in the tables in Weyerhaeuser's TB-611?
    – aquaticapetheory
    Commented Nov 23 at 18:57

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