Replies

1. Expert Member
   MALCOLM TAYLOR | Jun 24, 2026 11:52am | #1

   big_o,

   As a rule of thumb, LVLs can be used outside in any conditions where exposed OSB would be fine. So no direct exposure to rain, and limiting moisture rising from the ground below is important.

   They do sell Pt LVLs.

1. 
   big__o | Jun 24, 2026 12:11pm | #3

   Thank you. Malcolm.

   I currently have exposed I joists(like osb) under the main house with no issues observed so it looks like the lvl should be fine too as long as no rain water gets on it. It's 2 feet above grade and extremely well ventilated since it's fully open so not too worried about ground moisture

2. Expert Member
   Michael Maines | Jun 24, 2026 11:55am | #2

   Standard LVLs are generally intended for dry-use conditions and should not be used where they will be exposed to rain, splashback, snow accumulation, trapped moisture or prolonged high humidity unless the manufacturer specifically allows it.

   For an open pier-and-beam foundation, I would look for a pressure-treated LVL or another engineered wood product specifically rated for protected exterior or exterior exposure. Even then, it should be detailed carefully: keep it well above grade, protect the top of the beam from standing water, avoid water-trapping connections and allow it to dry freely.

   Outside air by itself is not usually the problem. Bulk water, poor drying and sustained high moisture content are the problem.

1. 
   big__o | Jun 24, 2026 12:13pm | #4

   Thanks Michael.
   It will be under the house so bulk water or standing water should never be a concern. The bottom of the lvl would be one foot above grade if I do a drop beam or two feet above grade if I do a flush beam.

1. Expert Member
   Michael Maines | Jun 24, 2026 01:52pm | #5

   The IRC model code allows untreated beams to be as little as 12" to grade: https://codes.iccsafe.org/content/IRC2021P1/chapter-3-building-planning#IRC2021P1_Pt03_Ch03_SecR317.1. Keep in mind that's the bare minimum allowed. It depends on your local conditions; if there is likely to be standing water, high humidity and/or little ventilation, I'd spring for treated lumber. Or go with the flush beam.

1. 
   big__o | Jun 25, 2026 12:26am | #7

   Thanks Michael. It looks like I can also use a 4-ply pressure treated 2x12 instead of 2-ply lvl. maybe I'll explore that route instead.

3. Expert Member
   BILL WICHERS | Jun 24, 2026 01:59pm | #6

   To add to what Michael said, I would also pay particular attention to whatever surface those LVLs will be bearing on. You want, at minimum, a good capillary break in those areas to protect the beam.

   Bill

1. 
   big__o | Jun 25, 2026 12:26am | #8

   Thanks bill. that's important. thank you for the suggestion