How to reduce header height? LVLs, sizing?

17 years ago

We are rebuilding an exterior wall that is currently 2x4 construction. We're widening the wall to 2 x 6 so we can insulate it better.

We're re-using the Anderson casement windows when we rebuild (with extension jambs). Longest span is aprox 9'6". We'd like to raise the windows up as high as possible without re-building the roof. Current header is (2) 2x10s.

It looks like two 1.75 x 7.25 LVLs would be plenty, but we'd still need to build that out to 5.5 inches, so I wondered if we could use three (3) pieces of 2x lumber and get the same strength. Like (3) 2x8s perhaps?

Does anyone have tables to see if (3) 2x8 would carry the same load as (2) 2x10?

Or have any other suggestions? (Other than, "hire a structural engineer" which I would clearly do if I won the lottery.) We can be safe and put the (2) 2x10s back, but I would REALLY like to raise those windows a bit!

Thanks!!

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Comments (2)

mightyanvil
17 years ago
I checked more carefully and assuming the existing header is not over-designed (a big assumption) three 2x8's will carry the same design load but the deflection will be right on the allowable limit of L/360 instead of at L/500 for the 2x10's. Two 7.25 LVL's will be very similar to the 2x8's if you use an E value of 1.8. If you use an E value of 2.0 the double LVL's will have a deflection limit of L/400.

No one can say if the existing header was sized correctly without knowing the loading. You should check the bottom of the existing header to see if it has sagged.

A way to get the header even smaller is to use a Better Header steel flitch plate.

Here is a link that might be useful: Better Header
Stacey Collins
Original Author
17 years ago
Oh, thank you so much for your time, mightyanvil. I really appreciate it.

We'll check the 2x10s and see if they've sagged. Do we just use a level to do so? I'm removing all the interior wall paneling today so we'll be able to see all.

I've sent an iquiry to Better Header as well, thanks for the tip.

Stacey
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