Drainage at ledger board of deck?

[Innovate1]

Looking at doing some updates of deck and have always wondered how drainage at the ledger board is properly done. Seems like it would always trap water where decking is parallel to house. In my case the deck has house walls on both ends so it can't drain out the ends either. I did this quick drawing. The ledger is standard 2 x material with actual of 1.5". The siding is hardy board and has a 1" piece above the deck. To have any drainage the decking would need to be slightly more than 1.5" from the house sheathing and over 1/2" from the hardy board. Never seen a big gap there. I ripped a bottom bevel on the board and added a line on the drawing to show that but haven't seen anything like that detailed anywhere. And it would need to be angled more to not have a big gap at the top and be big enough to not plug up with crud. How is this handled or is it just ignored?

 

[Rusted Nut]

There should be a piece of flashing going from under the siding, down over the ledger.

 

[Innovate1]

There should be a piece of flashing going from under the siding, down over the ledger.

Sure. Everywhere mentions flashing. But there is still a pocket above the flashing that doesn't have a way to drain.

 

[Youngandfree]

Flashing should have an angled middle section of the Z, not flat horizontal.

 

[Innovate1]

Yes, the flashing should slope. I have seen installations where it didn't. But you completely missed my point. The decking closest to the building pinches the flashing and leaves no place for water to go regardless of the slope of flashing. If both ends are blocked it can't run out ends. I suppose if flashing were taped at the joints the trapped water would eventually evaporate but that is a poor way to go. Maybe this drawing with flashing in red will help - and the decking board is normally closer to building for more overlap.

 

[OldDoItAll]

Ledger spacers, and don't **** the deck boards against the siding.

https://www.homedepot.com/p/Deck2Wall-Spacer-Reinforced-Plastic-Deck-Ledger-Spacer-D2W58/203586765

 

[carlaisle]

Sure. Everywhere mentions flashing. But there is still a pocket above the flashing that doesn't have a way to drain.

It will have somewhere to drain if you don't **** the decking up against the ledger. If the aesthetics of leaving a vertical gap are unacceptable, undercut the board at an angle. Benefit of the vertical space is you can easily tell at a glance if it has become stopped up with debris.

 

[Innovate1]

I had forgotten about spacers behind the ledger. Another method I ran across is to put the top of the joists above the top of ledger by enough to have an open gap that isn't easily plugged by small debris. I found one place that stated 1" but it seems 1/2" should be plenty. Undercutting helps but I doubt that gets done very often. Just spacing the deck planks away from the wall to clear the ledger could result in up to a 1" gap to the siding depending on the siding thickness - doesn't seem like a good solution or look.

Having the ledger slightly below the joists would work well where the planking was parallel to the building and perpendicular to the joists but on the ends where the planking is perpendicular to the wall the ledger supports the ends of the planks so needs to be same height as the joists. In that location the gaps between the planks would allow drainage.

 

[jar944]

The decking to flashing or ledger isn't water tight..

 

[Innovate1]

The decking to flashing or ledger isn't water tight..

If you are saying where the decking clamps the flashing against the ledger isn't water tight that may be technically true as a little may leak through but practically speaking it is water tight. The original deck installer here didn't space the deck boards and in short order little bits of crud plugged the gaps and we would have puddles of water on the deck long after rain had stopped. You need a significant gap to keep it from plugging with small debris.

 

[OccupantRJ]

If you are saying where the decking clamps the flashing against the ledger isn't water tight that may be technically true as a little may leak through but practically speaking it is water tight. The original deck installer here didn't space the deck boards and in short order little bits of crud plugged the gaps and we would have puddles of water on the deck long after rain had stopped. You need a significant gap to keep it from plugging with small debris.

I have a hell of a time with pine needles here plugging anything they can get to. They also work their way down into the cowl section of a car and cause issues. If there is a gap or a hole they will find it.

 

[cgrutt]

Route some channels across underside of the decking against house to act as weep holes would in a block wall.

And/Or

Leave a gap at ends of ledger board.

Or

Fill the gap with self-leveling sealant to prevent water from accumulating in the space you're concerned about and have it drain on top of the decking.

 

[BobnCO]

Ledger spacers, and don't **** the deck boards against the siding.

https://www.homedepot.com/p/Deck2Wall-Spacer-Reinforced-Plastic-Deck-Ledger-Spacer-D2W58/203586765

Well I’ll be F’ed.. I claim to be an old master carpenter and didn’t know those existed.. because the probably didn’t . Getting ready to do a deck this summer already cut back siding!
THANKS (I knew this sometimes grouchy forum was good for something!),

 

[Rusted Nut]

Yes, the flashing should slope. I have seen installations where it didn't. But you completely missed my point. The decking closest to the building pinches the flashing and leaves no place for water to go regardless of the slope of flashing. If both ends are blocked it can't run out ends. I suppose if flashing were taped at the joints the trapped water would eventually evaporate but that is a poor way to go. Maybe this drawing with flashing in red will help - and the decking board is normally closer to building for more overlap.

Cut a small kerf on the underside of the deck board.

 

[OldDoItAll]

Well I’ll be F’ed.. I claim to be an old master carpenter and didn’t know those existed.. because the probably didn’t . Getting ready to do a deck this summer already cut back siding!
THANKS (I knew this sometimes grouchy forum was good for something!),

I usually make my own from a cheap HDPE cutting board and a hole saw. You can quickly make quite a few out of a $20.00 cutting board. Don't really need the holes to attach, just the hole in the center.

 

[gahrajmahal]

Reading your post made me wonder what I did way back in 2013 when my deck boards rotted prematurely. The deck was installed by someone else, homeowners insurance didn’t cover it even though it was just eight years old. But, the lumber yard that supplied warrantied all the lumber and supplied new gratis! I was a poor working stiff back then and I rebuilt the deck with helpful advise from GJ members in this thread.

Pressure Treated Deck Repair, Opinions Please

Hi All, I have started to rely on the helpful opinions I have recieved from you, the members of the GJ. Back in 2005 I paid for somone to remove the original 30+ year old deck and replace it with this slightly updated design I provided. It was build from pressure treated #1 Pine with a permit...

www.garagejournal.com

Here are some select photos, marred by photobucket watermarks from that thread. I had to replace the band joist because the water seeped in between the ledger and the joist. The builder I hired didn’t flash behind the siding and over the ledger.











Here is the top view. There is about 1/2” of space between the deck board and the siding

 

[jkuro]

I always caulk the hole before I lag or bolt the ledger on.

 

[CraigStu]

Cut the deck board back so you have water flow over the top of the ledger. If the gap is too ugly find a piece of trim similar to quarter round or inside corner trim. Glue it to the siding leaving a vertical gap to the decking.

 

[Kaizen]

Lately they are coming out with large spacers that almost look like pieces of an i beam. They are coming into vogue with the addition of exterior insulated zip panels and the thicker 6" rockwool exterior insulation use. They attach to the sill with structural fasterners and make it almost like the deck ledger is floating so you can make an air gap. NS builders used them on a Rhode Island house on youtube.
Last deck I did years ago used rubber type zip tape up under the siding down over the sill and liquid zip an inch down to the foundation. Then cut pieces of decking (plastic stuff) and spaced the ledger out 5/8 from sill. Then put flashing as usual but longer so it was over the ledger. I did cut it and bend between the joists down so a majority of rain ran out. A million approved ways to do it now.

 

[andyvh1959]

When the contractor built my house back in 1973 they simply bolted the deck ledger directly to the 24' length of the deck, right through the cedar siding and into the sill joist (dumb asses). That west side of the house is always directly exposed to wind, rain, snow, sun, etc, only 6" overhangs leaves little weather protection. Here in Wisconsin that means lots of wet/snow being trapped against the ledger and siding, wet/freeze/expand/thaw/ repeat, no drainage planned, no flashing planned (dumb *** again). Back in 2012 (I bought the house in 2002) I noticed the cedar sidind was rotted, and as I explored it more found the cedar siding was rotted through, same for some sections of the sill joist.

So I suported the raised deck from below, cut the deck joists free from the ledger joist and ripped the ledger joist off the house. Cut off the rotted cedar siding, repaced almost 30' of sill joist with new pressure treated lumber, sealed and flashing, replaced the rotted section of cedar siding with an area of concrete siding, then used four preussre treated sections of 2x6 8" long spacers construction glued to the siding, then the new deck joist is lag bolted through the spacer and siding into the new sill joist. End result is a 1.5" wide gap for the 24' length of the deck attached to the house to provide draining.

I may yet install a length of gutter under the deck structure for the drainage from the deck gap to direct the water down to the sounth oed of the deck and away from the house.

 

[tarmy]

I had an old deck that was never attached correctly no flashed at all. I used a set of metal drip edges, bitchathane and bolted a 2x12 PT fully recessed and then attached a 2x8 with those 3” or so plastic spacers made to stand off the rim joist for the deck…about 1/2 off. Worked spectacula.

 

[firebirdparts]

Looking at doing some updates of deck and have always wondered how drainage at the ledger board is properly done. Seems like it would always trap water where decking is parallel to house. In my case the deck has house walls on both ends so it can't drain out the ends either. I did this quick drawing. The ledger is standard 2 x material with actual of 1.5". The siding is hardy board and has a 1" piece above the deck. To have any drainage the decking would need to be slightly more than 1.5" from the house sheathing and over 1/2" from the hardy board. Never seen a big gap there. I ripped a bottom bevel on the board and added a line on the drawing to show that but haven't seen anything like that detailed anywhere. And it would need to be angled more to not have a big gap at the top and be big enough to not plug up with crud. How is this handled or is it just ignored?

I like your thinking. You could bevel the top of the ledger instead, but yes, I like it.

 

[gba2331]

i like the idea of beveling the underside of the deck board (or routing an inset lip). You might add a thin strip of decking into the gap under the siding just to keep out larger material.

 

[Jackfre]

LAst summer I had to remount the deck on our place the PO had directly attacked the deck flush to the siding with predictable results. I removed 4 courses of the deck, short cut the joist and installed a proper ledger board after replacing the rot all the way into the rim joint. I went to a sheet metal shop for fabrication of my custom flashing. It was worth it as it was made out of 26ga metal and was long enough to cover the face of the ledger and inserted about 1.5” up under the siding

 

[jar944]

Or just flash from the sheathing to the flush beam.

 

[bluedog225]

Well I’ll be F’ed.. I claim to be an old master carpenter and didn’t know those existed.. because the probably didn’t . Getting ready to do a deck this summer already cut back siding!
THANKS (I knew this sometimes grouchy forum was good for something!),

They are grouchy as heck. But a lot of smart and experienced old men. Worth it.

 

[Burt Shaver]

If you are saying where the decking clamps the flashing against the ledger isn't water tight that may be technically true as a little may leak through but practically speaking it is water tight. The original deck installer here didn't space the deck boards and in short order little bits of crud plugged the gaps and we would have puddles of water on the deck long after rain had stopped. You need a significant gap to keep it from plugging with small debris.

Wouldn’t the space between the deck boards be enough for the water to drain away? That is, as long as the deck boards are inning perpendicular to the ledger board

 

[Burt Shaver]

Besides flashing the ledger board, I’ve also added a piece of flashing with a safety bend that extends under the siding and over the deck boards about 2 inches. Also put a slight bend in the 2” section that’s showing for ridgity. Stops most if not all water and any debris from entering at all. I also wrap the top of all my beams, and joists with synthetic underlayment for roofs.

 

[MongoTA]

@Kaizen "Lately they are coming out with large spacers that almost look like pieces of an i beam."

I've used something similar, even DIY fabricated them way back in the day. But the commercially available ones I know of are called Main Deck Brackets. They've been around for quite some time but for sure, new versions seem to pop up now and again.

 

[Innovate1]

Wouldn’t the space between the deck boards be enough for the water to drain away? That is, as long as the deck boards are inning perpendicular to the ledger board

Yes if perpendicular, but I am talking about where they are parallel to the ledger and have walls at both ends.

 

[Burt Shaver]

Yes if perpendicular, but I am talking about where they are parallel to the ledger and have walls at both ends.

I mentioned it my other post here, but after you put the deck boards on, I put a piece of flashing under the siding, out over the deck board about 2 inches. Put a safety bend in the edge that’s showing and also put a very slight bend in the 2 inches that’s showing. Keeps the water and debris from entering that area

 

[andyvh1959]

Wouldn’t the space between the deck boards be enough for the water to drain away? That is, as long as the deck boards are inning perpendicular to the ledger board

You'd thinl so, but no, for snow and ice that is. For rain alone its less of an issue. But here in the upper midwest the snow can easily adhere and fill all the board gaps. Then it melts a bit, and freezes. And soon there are no gaps and you get constant wetness against the siding for the depth of the snow abd the length of the deck. Even the 1.5" gap I now have between the ledger sill and the siding is sometimes filled by the snow. But it melts out faster and maintains a gap fro drainage better than just the deck board gaps.