How to Install a Deck Ledger Board and Attach Flashing | Trex Academy

A ledger board is a critical structural element of a deck that attaches your outdoor oasis to your home. Water and the elements can damage your ledger board, compromising both your deck and your home. Learn more about proper deck ledger installation and attaching flashing with Trex® Academy's step-by-step video instructions.
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Key moments in this video:
00:00 Intro
0:45 Back Flashing
1:38 Ledger Board Location
3:22 Ledger Board Length
4:51 Breaker Board Layout
8:09 Guardrail Post Layout
11:30 Joist Layout
14:19 Ledger Fastener Layout
21:35 Flashing Ledger Layout
24:19 Ledger Board Attachment

[@albelanger6126]

Wow. This is by far the best deck building video series. Extremely well done. Thank you, thank you, thank you❤

[@TheTrexCo]

We're so happy you've found this helpful!

[@spelunkerd]

As much as I complain about the Google algorithm, it suggested this outstanding video. Thank you!

[@dufreebell]

Great video with ton of information. Attaching a ledger board on a siding looks like a simple job, but you made it so clear that it’s not as simple as it appears. Thanks for sharing!

[@bartbug1]

Nice touch covering those Flashing joints, an important part that many skip.

[@kevinzep01]

I'm glad to hear you continually refer to the local building officials! Thank you!

[@bobrebera494]

good job

[@patty109109]

Saw some other vids in the series. Very high presentation quality and instruction 👍 dang you guys put a lot of posts in, though 😉

[@kevinzep01]

Good comment. The number of posts and max spacing between them will be dictated by the size of the beam and the loads placed on the deck. Not an arbitrary number.

[@peterbedford2610]

The last 4 minutes were actually about ledger flashing.

[@guruwazeer2926]

nice job

[@TheTrexCo]

Thank you, we appreciate you taking the time to watch our videos. - Trex Customer Care Team

[@hospitaladministrator3359]

This guy is super freaking smart

[@ahole5407]

Not really, it's just that the majority of people are dumb. 😂

[@cameronloeb8046]

for the bottom flashing, shouldn't you leave a pencil width gap below the ledger board? so that there isn't water resting in contact with the bottom of it

[@neeho2]

but how did you know your ledger lock screws were biting into anything? this video was very informative and i'm going to be using this information without a doubt! The only thing i need to know now is how to tell where i can screw into the house (my ledger is for a patio roof and needs to be somewhere in the middle of the house) the only meat i can tell to screw into will be the 2x6 outside wall construction of the house...? how can i tell where to screw my ledger in?

[@TheTrexCo]

On this project we had access to the unfinished basement, which allowed us to inspect the rim joist the previous deck was attached to. From the basement we found the rim joist was solid lumber, continuous and in good condition from that perspective anyway. We also inspected the rim joist from the outside of the house as we removed and replaced the rotted sheathing due to lack of proper flashing. Additionally, we had an approved building permit allowing us to attach the ledger to a solid lumber rim joist, which is what we found to be the case. This floor system and rim joist are pretty common for a home built in the 70’s. If you don’t know exactly what’s behind the area in which you’re attempting to secure your ledger to, STOP. You need a structural engineer to help you determine the best course of action. Your local building department will ask you for an engineer’s report anyway when you file for a permit since, from what you’re describing, is not typical. Always consult with your local building department as to what type of [house floor system] rim joist is approved for attaching your deck ledger specific to your project. Good luck with your project- Trex Customer Care Team

[@kevinzep01]

Great job. As a designer though. I have not used a bottom flashing as you do. Will water get trapped under the ledger?

[@patrickbinder4708]

Best thing to do is gap the ledger off the building using a spacer (Deck2Wall is one brand)

[@cameronloeb8046]

what type of fasteners do you use to fasten the flashing to the house?

[@cameronloeb8046]

why can the joists not conflict the rail post locations?

[@k_mitch]

I must be missing something. It looks like the 3 inch difference on the ledger board was taken all from one end with the ledger and rim flush on the other end. Since it's 1 1/2 inches from each end, doesn't that make the markings on the ledger board off by 1 1/2 inches?

[@redneek24]

You put up the beams before the ledger board?

[@christopherleblanc1461]

Can the butyl membrane go over tyvek house wrap?

[@krisallen9194]

I was under the impression that you need a barrier between the steel flashing and your pressure treated ledger. Did I miss you mention tar paper or some type of barrier to prevent corrosion ?

[@ksiverd]

Very helpful, however, at 7:33 when you're showing a small gap to catch the boards as they reach the breaker board... how do you properly attach joists to the ledger so close together? Is there a special bracket?

[@TheTrexCo]

Hello Ksiverd, I hope this message finds you well today. With those joists and blocking joists so close together, it is an interesting time getting all the necessary hardware that close. We started from the inside out and installed a joist hanger on the joist and attached it to the ledger. Then the next joist we cut just slightly shorter (about an 1/8”). Then we installed a Simpson Strong Tie L-70z onto the joist and had it face away from the adjacent joist. We then installed the nails through the L-70z into the ledger as it was outside the edges of the nearest joist hanger. Then the process was repeated on the opposite side. Please let us know if you have any additional questions or if I may be of further assistance. Kindly, Jaclyn Goodrich Trex Customer Care

[@scotta9114]

Was there a reason you didn't raise the entire deck so there isn't a step-down of 6 inches? Our has has no rim board, 1989 so I guess I need to screw into the wall studs to secure the Ledger.

[@stuckster]

For the ledger board instead of the steel flashing directing the water over the board, could you simply install plastic spacers between the house and the board allowing the water to run freely down behind the ledger?

[@TheTrexCo]

Hello, You can check with your local code official or building inspector to see what your local code is in your area. - Trex customer care

[@markvandam2378]

If repairing rotten lower run of siding touching deck due to improperly installed flashing, should the new flashing be installed over the existing housewrap as in this video, or should an incision be made in housewrap, so flashing can be installed under housewrap? Then incision taped over?

[@TheTrexCo]

Hello, thank you for reaching out. Feel free to give us a call at 1-800-289-8739 to discuss this further. - Trex Customer Care

[@jaredcrawford2829]

What “butyl membrane” do you recommend? I can’t seem to find anything except asphalt based stuff for roofing, and no one at lowes or Home Depot knows what this stuff is?

[@TheTrexCo]

Hi Jared. Thank you for reaching out and your interest in Trex products. We do not have specific brands to recommend, but the following are examples of waterproof membranes, VaproShield - Benjamnin Obdyke Roof & Wall Products - Dorken. Please feel free to reach back out with any further questions or concerns. Someone from our Customer Care Team will be more than happy to assist. Kind Regards. -Trex Customer Care 1.800.289.8739 | [e-mail]

[@jaredcrawford2829]

Thank you! I did find a product from GCP called “vycor” do you know if this product is suitable?

[@TheTrexCo]

Hi Jared. Thank you so much for reaching out with your follow up question. I apologize. We do not have specific brands that we recommend. However, as long as the product is approved per local code, waterproof and exterior grade, those would be the characteristics with in the water proof membrane we would like the product to have. Please feel free to reach back out with any further questions or concerns. Someone from our Customer Care Team will be more than happy to assist. Thank you for choosing Trex. 1.800.289.8739 | [e-mail]

[@michaelpiecuch7313]

How would you install the ledger board if you have foam board insulation on your walls

[@TheTrexCo]

Hello Michael, to go more in depth with installation questions, please give us a call at 1.800.289.8739.- Thank you, Trex Customer Care

[@edwardfernandez7516]

What's that tape on the flashing?

[@stevebabiak6997]

Two types of stick on products are possible. One would be a fortified joist guard product, such as G-tape. Something like this is most likely used on the seam of the metal flashing. The other would be a roofing ice and water shield, such as Grace Roof Membrane. Something like this was used on the sheething before the ledger board was attached.

[@jackmcgee1079]

Is there a link of installing the 6x6 post ?

[@TheTrexCo]

Hi! I believe this video will help you look into the installation process for installing the 6x6 post for the substructure. kzbin.info/www/bejne/nZ21fXyFhMqVY9E Please feel free to reach out if you have any additional questions. ~ Trex Customer Care Team

[@bobbg9041]

Ledger flashing. They make a round spacer to space the ledger out off the wall when installing this leave an airgap so water cant get traped behing the ledger and flashing. Becuse if the flashing gets dammaged and it can it will let water into interior untreated wood giving pests like ants a way in the distroy your home. This also gives water down the wall a path to drain and dry up. You can flash and seal these joints better then just some stick on material that can come unglued from heat. Metal flashings always better copper and lead are the best I dont think you can use lead anymore but you can use copper just use copper nails also not galvanized.

[@MeMe-ng7lp]

That’s usually only used on brick

[@patrickbinder4708]

Strange way of doing a breaker board (spine). I create a ladder (blocking) between joists picking up the long boards. Uses scrap, goes fast, breaths well.

[@knoxflyer101]

I only have 12.5 inches from ground to bottom of my sliding door. Can I just install joists and not drop beam?

[@TheTrexCo]

Thank you for reaching out! We would request to reach out to your local code official to be sure this would be an approved installation method. Thank you. ~ Trex Customer Care Team

[@jsharick7]

Sorry if I missed it, what does 16 inches on center mean?

[@TheTrexCo]

Hi there! Thank you for reaching out. 16 inches on center typically refers to the maximum joist spacing we allow for our decking boards as long as the joists are running perpendicular to the decking boards, and it is a residential not a commercial application. If you have any other questions, please let us know. We are able to be reached at 1-800-289-8739. Thank you! ~ Trex Customer Care Team

[@deeeeeeps]

That bottom drip cap needs to be lower if you want to do that...in the video you can see it's just a water trap.

[@openhand7502]

Can anyone explain why the bottom flashing is better than just leaving the bottom of the ledger board unflashed so it can air dry? Seems to me capillary action would keep water against the bottom of the ledger.I guess I'm saying what Deeeps is saying, just in another way.

[@TheTrexCo]

Hello, thank you for reaching out! The bottom flashing is to prevent water from flowing under the ledger board and behind the siding below. This will prevent water from seeping into the wall below the ledger board and degrading the structural integrity in the wall of the house. Please let us know if you have any questions. 1-800-289-8739. Thank you, Trex Customer Care Team

[@RedRupert64]

@@TheTrexCo Rather than the bottom flashing, perhaps it would be better to cut the bottom edge of the ledger board to 30°+/- so as to form a drip so that any water cannot flow towards the house?

[@TheTrexCo]

Hello, and thank you for reaching out with your question! For your question, this may be something you would want to ask your local code or building official, as they should be able to advise if this would suffice. The most important thing is to make sure the house has back-flashing and to keep water from getting behind the ledger. There are numerous installation methods for flashing, such as the one shown here. If you have any further questions, please call us at 1-800-289-8739 as we are happy to assist. Thanks - Paul, Trex Customer Care

[@dacedruss]

dO THIS

[@angetodac]

My deck won't be attached to the house!

[@bobbg9041]

The breaker board in the center of a 22' deck looks like crap. It is not appealing at all. What i would do is make up the lenth by adding a outside rim of boards as a picture frame around the feild you can miter the conners for a lot better over all aperance Yes it will require a few extra joits to hold the floor on the ends or even other methods for something to screw down to but the exter framing members will make the deck even stronger. Then if youve got a 44' long deck you can add a picture frame side by side and its not going to look out of place like 1 2x6 down the center. That just looks stupid and cheap.

[@christophergallagher531]

Why not title this one, lay out? Then make one actually about flashing and fastening a ledger.

[@chopshop523]

Why did you have holes in your protective flashing? Smfh!! All that work and you managed to put holes in the flashing. What if that little piece leaks? That’s not the proper way to cove the flashing by sticking a small piece on. Come on pro!!

[@TheTrexCo]

Thanks for the feedback. We can definitely understand the concern but the holes were not made purposely. During the building products, small nicks or cuts can be unintentionally made in the back flashing. We just wanted to exemplify covering up these areas to prevent any moisture from penetrating the house framing. Please let us know if you have any questions. Thank you! - Trex Customer Care Team