Avoid Disasters: How To Properly Flash A Deck || Dr Decks

I've seen so many examples of deck rot because some carpenters don't flash their decks. It's relatively simple and inexpensive to do and will save you tons of money in repairs in the future. In this tutorial I'll go over the best ways to do it to keep your deck, and your home, waterproof.
-----------------------------------------------------------------
Connect with us:
/ drdecks
www.drdecks.com
-----------------------------------------------------------------
Recorded & Edited By: linktr.ee/calv...
#drdecks #deckbuilding #diy #homeimprovement #howto #tutorial #howtoflashadeck #waterproofdeck #howtoflashahouse

[@pennybergmen8933]

You’re very generous to share what you know to so many people!

[@drdecks]

Thanks!

[@brentdreamer2025]

The perfect video for my deck project. I am building a log cabin and the deck is mostly covered by the extended roof but I learned quite a bit about styles of flashing in addition to the tape I am already using. Thanks again and keep the videos coming Jason.

[@drdecks]

You’re welcome!

[@jeremysawesome]

Much appreciated! I'm working on a deck project right now and just finished flashing the ledger, this just uber boosted my confidence that I'm doing it right. I'm very curious about that next video you mentioned in which you re-trim/side over the waterproof membrane, that's likely going to be something I have to do soon.

[@pcatful]

Thanks! Great variety of approaches shown! Alternately I prefer to leave the deck ledger spaced off the wall and let the wall be the weather barrier instead of interrupting the weather barrier. I like how you use of flexible flashing bemeath the metal flashing. The metal protects the flexible flashing from UV and secures it better. The flexible flashing at the top is good as well for remodel to make sure the weather barrier is continuous. There's always differences, whether this is new construction or deck addition, and what the siding is. Your decking board will be going parallel to the wall. I"d notch the first board at intervals on the bottom so the water isn't trapped at the flashing.

[@Sparisland]

Don't forget to flash the top of the siding below the ledger because water will run down the front, along the bottom, and back under the siding if you don't. Even if you think the flashing above the ledger extends far enough, the wind will blow drops of water back against the ledger board.

[@CMCraftsman]

Yeah I put a kick out flashing with a hem bend under the ledger. It’s important to keep it 1/4-1/2” down so you don’t hold water in tension between that kick out and the ledger. It comes down the wall, bends 90° out 1 1/2” then down on like a 20° angle or so another 1 1/2” with a hem bend to drip off of.

[@SLickev92]

@@CMCraftsmanwhat would you do if the existing flashing is either failing or wasn’t installed correctly and water is leaking below ledger , behind siding and the osb sheathing is soaking it up .

[@ilovebooms1221]

@@CMCraftsmanhey what do you do to get over the trim around the siding?

[@jbthefirst960]

About to do this for my own deck. Thanks for the video!

[@deeparker6109]

Just the video I needed, in the UK we usually have brick exterior walls, but just replacing a deck on a timber building and the person who built it in 2010 didn't flash it so the OSB sheathing and about an inch into the joist behind it had rotted, can't really find any profiles like you have but I'm going to rip a square section of UPVC downpipe along its length to create the profile. Great tips, thanks.

[@alamedajon1453]

Informative good video, I'm subscribed. I am about to pull a deck away from the wall because of rot. bracing first, the deck is at a height of 7 ' no bracing under the deck. It was attached to the house. I'm hopefull the wall above will not crumble as i need to reclace a 4x6 x 12' header.

[@cleanearthhaulingjunkremoval]

This is great to see. I want to ask how you would flash a stucco wall? Remove stucco where the ledger is to be installed and flash or leave the stucco and caulk the lag screw holes? Your input is greatly appreciated.

[@jason8795]

Dr. Can you use membrane tape over tyvek or should the membrane go directly on the wood?

[@davidkroner3677]

Recently we began resurfacing an old deck. The joist had been run through the brick veneer and attached to the house. Thankfully the joist were in great shape but after adding the EPDM bays I am struggling with the best way to flash against the brick to keep water from later ending up in the finished ceiling. How do you flash the brick? Do you use a termination bar, cut into the grout and add flashing like a chimney or something else?

[@EtoTheKay]

I'm finishing my deck now and wondering the same thing. What did you end up doing to seal the ledger flashing against the brick? Please let me know!

[@frankcampos1251]

I’m planning on building a pergola with an attached ledger board to the side of my house that has a bay window with vinyl siding. Do you have any suggestions or videos on how to seal and waterproof around the ledger / vinyl siding?

[@knoxson6clips453]

Absolutely love your stuff, watched hours of them for advice on composite and PVC installs, but at least 1 3/4" on the flashing to provide a capillary break. That way the water will not drip down the ledger

[@LuisLarreaJr]

Does this only apply to wooden homes or also brick?

[@LuisLarreaJr]

Feel kind of stupid asking because the consequences you mention is water getting into the home. With any surfaces other than wood, this won't happen. I guess I was worried about the back of the board not drying out and rotting.

[@joeltrotter4795]

Don’t the chemicals in the pt eat through the aluminum flashing? Same thing with galvanized. I always use thin rolled copper.

[@huejanus5505]

I know the old pressure treating chemicals were rough on anything metallic, i’m not sure about the new stuff though.

[@mikegander305]

In my area the pt lumber is treated with copper chromium and arsenic. Yes, the copper reacts with aluminum. Butyl tape, or as he stated, gtape would be a better solution.

[@CMCraftsman]

You can use the butyl tape as a capillary break between the aluminum and the pt so there’s no worry of the materials touching each other

[@didster2000]

Sorry if it's already been asked but how do I flash a new ledger board going against an existing stucco wall?

[@robertmontgomery3892]

I'm rebuilding a 10x40 foot deck that is around 30 years old. In my case the deck is freestanding and supported by concrete piers. So there is no Ledger Board in my situation so most of this video doesn't apply in my case. But... I intend to install 2x6 facia boards around the perimeter of the deck and I intend to use Z -bar between the facia board and the T1-11 skirting. I thing this is appropriate but are there other places where I should consider using flashing?

[@silverlakegirl9078]

Your videos are my go-to! Much respect!

[@marcellinasfigaro9364]

I watched a couple of other flashing videos and they installed ANOTHER piece of Z flashing besides the one that covered the ledger board, that was L shaped and also went behind the siding and sat ON TOP of the decking itself probably a couple of inches. Seemed like overkill to me. What do you think?

[@amandaharvey2885]

The guy who owned my house before didn't install flashing before laying down the deck AND he built it too close to the house...I'm hoping this is something me and my partner can fix. Great video!

[@awood186]

Does your surface decking have to go all the way back on the flashing or can you leave a gap? and if so how much gap?

[@anthonycarroll6546]

I appreciate your videos. I have to ask though, I've been reading the c9de for deck building and aluminum should not be used against pressure treaded lumber. What is your take on that?

[@nettle99]

When the deck board closest to the house, especially if it runs parallel, gets screwed down it doesn't leave an exit for the water to trickle down in between the flashing. I find this odd to be common practice and up to code, especially if the siding comes right down to meet the deck boards. "Deck2wall spacers" seem like the best option out there to leave breathing room for drainage and debris buildup.

[@candiceeckelberry7524]

Do you put a spacer like a washer between the ledger and house wall?

[@daver7867]

i do, probably an old school thing but it makes sense.... water doesnt get trapped...

[@MattFerguson26]

Deck2Wall spacer? It seems like that’s point load the ledger, thinking if there’s something bigger but give that drainage gap, like thin/wide strips.

[@howtodoitdude1662]

@@MattFerguson26definitely strips would work better than washers. Washers would sink into the wood when tightened the ledger board.

[@CMCraftsman]

You can. They actually make one, can’t remember the name of it

[@TakeNoneForTheTeam]

Could you do vid on how to install the liner when you're blocking for top mounting railing that uses 4 bolts? When I go from the house out to gutter, where does that water go? Do I just block it all (house to gutter) making it flat and then it just is what it is (no trough)?

[@bdubs8620]

The box of coil stock I just bought a few months ago (sometime in 2024 ) says right on the box in bold text : DO NOT USE OVER TREATED LUMBER Everyone oughta know by now (it’s been 20 years since they changed) the new age treated lumber is more corrosive to metal .. even the galvanized fasteners we used to be able to use had to be replaced with “zmax” and coated deck screws.

[@rosewoodsteel6656]

Correct! My opinion is, if you use aluminum flashing, it must be isolated and shouldn't directly touch the pressure treated lumber. I have isolated aluminum flashing with 30lb roofing felt, but the (expensive) tape shown in the video would work fine. Note that no surface of the aluminum, top or bottom, should be in contact with the MCA treated lumber.

[@timbrown9305]

Extra deep flashing keeping the drip line away from the ledger is a fantastic practice. Outside scope but treat your cuts/joist ends. I am applying sticky butyl tape as well with heat gun. Built decks and remods for 45 years. I take offense to the "some old guy" comment, it's the new guy's that don't know crap... I've made every mistake possible, that's how I know what NOT to do.

[@jjtrades7186]

I never use aluminum, the chemicals in the pressure treated lumber will eat the aluminum. I use nervous-straw (not sure they even make that anymore) but it's a vinyl sheet flashing like rubber and comes in 1ft out 2ft rolls and I use the whole width. I go 6" up the wall and a foot and a half out onto the joists so the ends of the floor joists also don't rot

[@BrentLagerman]

would love to see more vids on how you connect the bladder to the house

[@johnnynewburgh9745]

Why don’t they add a couple of more 4x4 posts and keep ledger independent of house and leave 1/2 gap

[@erichula6230]

What about flashing on T1-11? How do you handle all those groves?

[@kevincasey2947]

Do you have any issue with asphaltic paper behind a deck ledger?

[@BenElliott33]

What about aluminum to PT lumber chemical effects. I assume gtape it to address this issue or plastic flashing between the two.

[@tomanderson9064]

Do you need to do flashing if the siding is existing T111 siding??

[@stevensauerbry8037]

I am redoing my deck and the ledger board and joist are in. I am picture framing it and the old flashing is nailed through with no membrane. What’s the best way to cure this. I can’t take it all apart.

[@dcole7092]

I've used weather tape, flashing and put roofing paper across and down the ledger for even extra protection for the house and ledger.

[@Icehso140]

After I sided my house, we had leftover 24" flashing 180" long. Replacing my 12 foot deck behind the garage, I used the 24" flashing all across the sheathing in one flat sheet over the Tyvek. Then we figured to height of the floor boards and mounted a 1x8 PVC board all the way across as a snow barrier and framed the siding above it. I then had 1x3 pvc boards left over and used them to space the ledger off the flashing vertically and used longer screws to mount the ledger to the garage framing. I did this to keep water from being trapped between the ledger and the flashing. I know...overkill. But I didn't need siding material hanging around and I'm retired and have all the time in the week to go the extra mile.

[@frederickdriesbachjr2110]

What if the ledger board is attached to a brick wall? How do you do flashing with that situation?

[@GH-qi1wv]

So if you have concrete wall you dony need it ??

[@mil-specgarage55]

What about brick?

[@Aelanna]

An 'old contractor' put three decks on my mom's house 20 years ago. None of them were flashed. I am now having to tear all three down, repair the damage to the house where sill plates and rim joists have rotted away, and rebuild all three decks.

[@cgchase571]

Very helpful - thank you

[@Toprankedpdx]

Also any pro should address flashing down the end grain (sides) of the ledger. Also rabbeting the out the back of the bottom of ledger is a good idea to lap the siding which prevents surface tension and water running behind siding.

[@jackfarrell4727]

Worthy effort dude. Why did you not actually put the stuff on to the wall and ledger? And be redundant, keep the pressure treated lumber from the flashing. Use galvanized fasteners etc.

[@802brundogsaint]

Thanks!

[@Christopherjamesmurphy21]

I do the second opinion. I bend the metal at the hardware store on a break. That way, there isn't a return down to get in the way of my joist.

[@lancerman]

These jack wagons in Nevada don’t waterproof decks. I guess they don’t think it rains enough here.

[@HappyMick-j5o]

What's the story with using galvanized flashing with ACQ treated ledgers? Maybe I should put a layer of peel & stick on top of the ledger before installing the flashing? Ideas/comments appreciated.

[@stevensauerbry8037]

Best way to cut around post during picture framing and 45s

[@CMCraftsman]

Don’t. Use a flush mount structural post that mounts to the deck after decking is installed. Unless you’re doing a wood deck like ipe or cedar but if everything you see and touch is composite and pvc, I’d never use wood posts again.

[@nrodgers4882]

Can I z flash and tape directly to osb?

[@CMCraftsman]

Assuming you’re wanting to cut your WRB and fold it up, flash the ledger, then fold it down over the flashing, I’d recommend using Siga Fentrim for taping to the osb and over your flashing.

[@pennybergmen8933]

I was very disappointed you weren’t wearing a long raincoat…….😂

[@Toprankedpdx]

C'mon doc.. why is there no self sealing membrane behind the ledger and and why are you telling people to screw through flashing. Always add a secondary ledger with joist spacers to screw the boards down. Or just glue the boards down on the ledger. Screwing holes in the metal completely negates the flashing..

[@jeffgarner3178]

Sorry but this video is Old school because chemicals in the treated wood deteriorate the flashing. New school is to use a plastic tape type flashing.

[@CMCraftsman]

The flashing we can get near me is a painted heavy gauge aluminum. I just put tape over the ledger as a capillary break between the PT and aluminum. It’s important to use a tape that’s ok to use with pt like joist tape and not ice and water or something

[@kevinshafer4296]

New treated isn't like the old ACQ. As long as it's not bare aluminum it'll be fine. Get galvanized flashing then no issues. Butyl based membranes work great or acrylic tapes.

[@vikingnorm6935]

@@CMCraftsmanOh boy!! I just tore down a 20 ft long concrete porch that was put on my house in the early 80’s, no PT or paint even let alone flashing, had to replace the rim joist & sill plate it was almost non existent, so I got a bunch of pieces of Ice & Water from my buddy for free he saves the longer stuff left over from work, put it on the rest of the sill plate & joist & the new, thought it would help, then flashed & used the membrane tape on the ledger board, oh well, live & learn I guess

[@bdubs8620]

@@CMCraftsman There would be no capillary movement into aluminum Metals don’t absorb water

[@angetodac]

I dont attach it to the house

[@angetodac]

Yes, 3 by 3 for me

[@yvonnelinyear172]

what about brick

[@JeraldHuffman]

TREX LEDGER TAPE

[@Maccongroup]

Waterproof membrane tape like that isn’t self sealing…

[@jonathanhonerbrink9886]

Definitely missing multiple steps .

[@teamdada2194]

idk about this advice.

[@Ptrrtp]

What about flashing on brick? Block? Concrete?

[@EtoTheKay]

Exactly. You get an answer?

[@milimora5398]

😂