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Discussion Starter #1 (Edited)
Hi,

I have an existing second story deck over a concrete patio, which we want to waterproof and therefore need to add a grade to the deck surface for water run-off. The deck is approx 40x10.

The current thinking is that I can use screwjacks to support the deck while I cut approx 2" out of the support posts and then lower and reattach the support beam to the posts. I am worried about the effect this will have on the ledger board where the joists are attached, i.e. will the residual stresses have an effect?

Also, it doesn't look like the ledger board is attached using lag bolts or the like. How else would they have attached this back in 1998? Was it code then to use lag bolts or similar?

Thanks
Chris
 

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Picture did not come out.
And your right to be worryed.
 

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Discussion Starter #4
Wierd about the picture. It shows up in Chrome, but not IE. If you click on it in IE though it displays OK...
 

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Discussion Starter #5 (Edited)
Joe,

I looked at the undersurface drainage systems, but we get a lot of tree debris around here and I think it would be a maintenance nightmare. Plus we want to install potlights etc underneath the deck. Also there is a lot of blocking (for the non-square corners etc), sistered joists etc that makes the underdeck systems very difficult to install.

Thanks
Chris
 

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Hi,

I have an existing second story deck over a concrete patio, which we want to waterproof and therefore need to add a grade to the deck surface for water run-off. The deck is approx 40x10.

The current thinking is that I can use screwjacks to support the deck while I cut approx 2" out of the support posts and then lower and reattach the support beam to the posts. I am worried about the effect this will have on the ledger board where the joists are attached, i.e. will the residual stresses have an effect?

Also, it doesn't look like the ledger board is attached using lag bolts or the like. How else would they have attached this back in 1998? Was it code then to use lag bolts or similar?

Thanks
Chris
Ayuh,.... 2 inches in 10 feet is too much,.... It'll be noticeable walkin' it...

An Inch is plenty...
 

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Discussion Starter #7
Thanks Guys,

I think I will aim for about 3/16 per foot grade. Minimum for the material is 1/8, but they recommend 3/16 to 1/4.

A question regarding attaching the ledger board to the house:

Currently the deck is prevented from pulling away from the house, or shearing vertically, using the nails that are driven through the joist hangers into the ledger board / rim joist. The ledger board is then attached very securely to the house structure (rim joist) using lag bolts. However this just prevents the ledger board from going anywhere; the joists are still only attached by the nails holding the joist hangers. A chain always fails at its weakest link, so why are the lag bolts necessary (assuming of course that the joist hanger nails penetrate through both the ledger board and the rim joist) ?

I know code is based on sound analysis and experience, so I must be missing something. What am I missing? And fell free to berate me if I am missing something blatantly obvious! :laughing:

Cheers
Chris
 
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