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How to mount a deck ledger on a Larsen truss wall?

We need to mount a 2x8 pressure-treated deck ledger to a conventionally framed wall that has a 8" larsen truss attached to it.

The frame is as such: 2x10 rim joist bearing upon 2x6 mudsill, 5/8" T&G OSB, 8" Larsen truss, 1x4 cross-strap, Tyvek. The deck ledger will be mounted at the same elevation as the rim joist.

The supported length of the deck is not too great, between 5-8'. I would like to attach the ledger on the same plane as th 1x4 strapping and not directly against the OSB.

Does anyone know of a detail for this? i been trying to come up with a detail where the ledger is bolted to the rim joist with long carriage bolts with squash blocks preventing the trusses from getting crushed, but I would need an elegant way of keeping the ledger spaced off the Tyvek to allow for drainage, etc.

We plan on using 1/4"-3/8" cedar lathe for the rainscreen.

Thanks again, gba.

Asked by erik olofsson
Posted Tue, 11/27/2012 - 12:53
Edited Tue, 11/27/2012 - 13:12

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3 Answers

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1.
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Erik,
I have never been a fan of deck ledgers. (To see the type of rot that can happen when a deck ledger is poorly flashed, check out All About Wall Rot).

The GBA Encyclopedia recommends against deck ledgers: "The best decks have no ledgers. Ledgers are the most vulnerable part of a deck, and they should be avoided entirely if possible. A free-standing deck with an independent foundation will last longer and cause fewer problems than a deck that is attached to the house with a ledger."

So why not just install a few more piers, so that your deck has an independent foundation?

Answered by Martin Holladay, GBA Advisor
Posted Tue, 11/27/2012 - 13:07

2.
Helpful? 0

i considered having the deck self-supporting but decided against it as i didn't want the footings nearest the house to be both bearing on the perimeter drain and rainwater leaders and above the frost line. i reasoned i could flash it properly as the ledger is quite simple: one staright 16'er. alas, it is -10c outside now...!
thanks again for your help, martin

Answered by erik olofsson
Posted Wed, 11/28/2012 - 22:59

3.
Helpful? 0

Erik,
If you install a beam parallel to your house, and then cantilever the deck joists over the beam, then the piers closest to the house don't need to bear on the footing drain.

Answered by Martin Holladay, GBA Advisor
Posted Thu, 11/29/2012 - 06:00

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