Decks, Patios, Porches and Docks - Deck Ledger - space away from T1-11?

I'm building a 21' x 10' deck, with the 21' length being attached to the house. 2x10 framing, with the beam (2 2x10's) being set back a foot.

The issue I have is the siding. The old deck was a ~10' x 10' deck, flush against T1-11 siding, no flashing, no air gap. The siding behind the ledger rotted away. I replaced the small section of siding with pressure treated plywood, as it will be invisible when the deck is installed.

My question relates to both how the ledger is attached to the house, and if I should space it 1/2" from the siding or not.

I'm using 3/8 - 4" lag bolts, going through the siding right into the rim joist.

If I space the ledger away from the siding 1/2" with washers, do I need to have a second beam (ie, a beam 2' from the house, and a beam 9' from the house)?

If I end up spacing it 1/2", should I replace the 10" x 10' strip of treated plywood with T1-11?

Instead of using screws, should I use a threaded ledger bolt - I have access to the rim joist inside the house basement. Or, should I only use ledger bolts in a few places?

Thanks!

John

John -


This should take care of some of your questions:

1. Use 1/2" lag screws or bolts. Make sure they are hot dipped galvanized (compliant with ACQ lumber). Bolts are stronger than screws and if you have easy/good access..I recommend it. Its not necessary..its just better. You'll have lots of decisions like this to make during the project. Force yourself to do the 'best' option on the most important parts - ledger board being one of them. At least put a few bolts in.

2. For 2x10 joists - you can have up to 14 feet of span so you will be fine with 1 beam. I don't think the 1/2" washer space changes that at all.

3. I'm guessing you want to use the 1/2" washer space to allow for proper drainage??? Please write back on why you want to do this.....

First - tell us what kind of siding it is. T1-11 is a pattern - it could be plywood, cement board or vinyl. Is it vinyl siding?

I don't think you need to replace the pressure treated plywood you have installed. What you do need to do it properly flash the ledger with vinyl or copper flashing. I'm a fan of the easy to use vinyl flashing sold in 50' rolls (16 or 24 inches wide). I put one behind the ledger tucked high up (4-6") under the siding above the ledger. Then I used a second flashing (J-channel) that also tucks up under the siding, and sits on top of the ledger board.

I'd prefer to have the ledger flush against the house (when properly flashed and caulked) and not use the spacers, but I"ll let the pros comment on that.

1. Use 1/2" lag screws or bolts. Make sure they are hot dipped galvanized (compliant with ACQ lumber). Bolts are stronger than screws and if you have easy/good access..I recommend it. Its not necessary..its just better. You'll have lots of decisions like this to make during the project. Force yourself to do the 'best' option on the most important parts - ledger board being one of them. At least put a few bolts in.

I just ordered 3 - 1/2"-8" bolts with the rest of the framing (to be delivered this week). I already have 3/8"-4" long lag screws (proper for the newly treated lumber). I have 20 of those. It's a bit overkill... but I had to make the ledger board out of 3 boards (8', 8', and 58").


2. For 2x10 joists - you can have up to 14 feet of span so you will be fine with 1 beam. I don't think the 1/2" washer space changes that at all.
OK!

3. I'm guessing you want to use the 1/2" washer space to allow for proper drainage??? Please write back on why you want to do this.....
The reason for the drainage...

The siding is T1-11 wood. Painted (actually a base layer of stain (when built, about 20 years old) that has been painted over about 5 or 6 years ago).

I am not cutting into the siding, so I want the space between the ledger and the siding to stay dry, and if it gets wet, then I want to let it have airspace to dry. The siding rotted away from the house where the old ledger was (then again, it was never flashed either).

I can only (properly) flash above the ledger where the windows are. It's like this:

4" side trim|17" siding|6' of windows|6' window/door unit|4" siding|6'window/door unit|5.5" siding

The ledger starts at the 17" inches of siding, and runs under the windows and door units. Below each unit is a 3" piece of cedar trim. I would have to remove the caulking from the bottom of the trim piece, slip the flashing underneath, and re-caulk (both behind and on top of the flashing).

I'll post a picture before the weekend.

The *problem* is that above the ledger in a few spots - 17", 4", 5.5" - there is no break in the siding to put flashing into. I can lay the flashing alongside the ledger board if that would help, even if it's not tucked behind any siding.


First - tell us what kind of siding it is. T1-11 is a pattern - it could be plywood, cement board or vinyl. Is it vinyl siding?
Plywood (I didn't realize they made T1-11 in different materials!).



I'd prefer to have the ledger flush against the house (when properly flashed and caulked) and not use the spacers, but I"ll let the pros comment on that.
I've heard mixed things. Some say to caulk the ledger to the house, others say not to. Some say to space the ledger, etc...

Thanks!

John