Deck ledger connection without a rim joist.

[BN4537]

So, I was doing a framing inspection for a house with a basement. There will be a deck attached to the backside of the house that you can step out onto from the first floor. The floor is built with trusses on 24" centers, as shown, and there is no rim board whatsoever, just OSB sheathing on the outside of the walls. The contractor intends to lag the ledger board into the ends of the trusses to bear the weight of the deck. The deck will be 5'-6' above finished grade.

There is no provision in the IRC for attaching the ledger board to anything other than a rim joist, so technically this would not be code compliant without an engineer's input.

How would you handle this? We are in the 115mph wind zone.

 

[SCBO1]

The contractor intends to lag the ledger board into the ends of the trusses to bear the weight of the deck.

Not sure I've seen a deck ledger lagged into the ends of the trusses and it looks like the deck can not be cantilevered due to the duct work.

Option 1: Look for the SBCA’s research report Attachment of Residential Deck Ledger to Metal Plate Connected Wood Truss Floor System

Option 2: Free standing deck?

 

[Mark K]

Fastener values into end grain are different from fasteners installed in side of member.

This is a case that calls for an engineer.

This is another example of an attempt to apply the IRC to conditions not considered when it was written.

 

[steveray]

And let us know what you come up with...

 

[e hilton]

Fastener values into end grain are different from fasteners installed in side of member.

It’s not end grain, the vertical end member of the truss presents side grain for the fastener.

I would say no, and let them come up with a solution. PCinsp option 1 may solve it, but i would mention the document to the builder and again let him research. He could also contact the truss manufacturer.

 

[Joe.B]

I agree I think this calls for an engineer. I would think that the engineer would probably want to confirm with the truss manufacturer/engineer that the connection would be allowed without compromising the truss design. Free standing deck sounds good to me, but as has been discussed here frequently, that may also require an engineer.

 

[fatboy]

Joe B has my answer.

 

[BN4537]

Thanks for the help. That is basically what I thought... Although I am intrigued with the SBCA’s research report Attachment of Residential Deck Ledger to Metal Plate Connected Wood Truss Floor System. I will look definitely look that one up.

 

[BN4537]

I'm kind of surprised that there isn't a detail for this in the IRC - lots of houses are built with floor trusses... Hardly ever see solid lumber joists anymore. I frequently see I-joists, but they have a rim board to ledger into.

 

[tbz]

So, I was doing a framing inspection for a house with a basement. There will be a deck attached to the backside of the house that you can step out onto from the first floor. The floor is built with trusses on 24" centers, as shown, and there is no rim board whatsoever, just OSB sheathing on the outside of the walls. The contractor intends to lag the ledger board into the ends of the trusses to bear the weight of the deck. The deck will be 5'-6' above finished grade.

There is no provision in the IRC for attaching the ledger board to anything other than a rim joist, so technically this would not be code compliant without an engineer's input.

How would you handle this? We are in the 115mph wind zone.

View attachment 8271

I would have the contractor supply the documentation from the truss manufacture that the deck ledger can be fastened to their product the way the contractor plans to, most of the truss manufactures will tell you that their product is not designed for that type of attachment and I doubt the sealed docs from them for the floor system have anything on them about that type of attachment.

Thus kicks it back to require drawings for the deck IMO reviewed and sealed by a lic. engineer.

The floor system manufactures really don't like things attached to their product, the contractor might be able to add single width powerlams between the trusses as blocking and attach to them, but not the end grain of the trusses without manufacture approval in their documentation.

IMO

 

[Joe.B]

Can't wait to see what Glenn has to say on this.

 

[Joe.B]

@Glenn

 

[patrickjames]

Engineer report.

 

[patrickjames]

2018 IRC R502.8.2 Engineered Wood Products

Cuts, notches and holes bored in trusses, structural composite lumber, structural glue-laminated members, cross-laminated timber members or I-joists are prohibited except where permitted by the manufacturer's recommendations or where the effects of such alterations are specifically considered in the design of the member by a registered design professional.

 

[Glenn]

Not sure I've seen a deck ledger lagged into the ends of the trusses and it looks like the deck can not be cantilevered due to the duct work.

Option 1: Look for the SBCA’s research report Attachment of Residential Deck Ledger to Metal Plate Connected Wood Truss Floor System

Option 2: Free standing deck?

The first reply is good for me. Option 1 is exactly what I teach and encourage. Option 2 (freestanding) opens up a much bigger can of worms and I don't encourage it for anything other than ground level decks.

Follow the link. Provide it to your contractor. Carry on. Sorry I can't be more useful.

https://sbcindustry.com/deck-ledger-attachment

 

[Glenn]

I'm kind of surprised that there isn't a detail for this in the IRC - lots of houses are built with floor trusses... Hardly ever see solid lumber joists anymore. I frequently see I-joists, but they have a rim board to ledger into.

I know a guy with over 20 IRC deck proposal drafts already written for the January deadline for IRC 2024. He represents the deck and railing industry in code development. He loves to hear input from the industry about what could make the IRC better for decks. Good thing he's always watching everything I post online, so now he knows your suggestion.

I'll put it on my list. Ha, ha!

However, I'd start my research with the document and organization I just posted.

 

[e hilton]

I don't encourage it for anything other than ground level decks.

In this case the deck is less than 6 ft so freestanding should be a viable option.

 

[Glenn]

In this case the deck is less than 6 ft so freestanding should be a viable option.

With an engineer for lateral bracing. Prescriptive method requires braced wall panels. Decks don't have walls. I'm teaching a 90-minute webinar this Thursday called "Deck Codes and Lateral Loads" where I discuss so much of what is missing in the code and makes freestanding very problematic.

www.BuildingCodeCollege.com/webinars/lateralloads

 

[e hilton]

I’m certainly not going to argue with you, but page 10 of the awc deck guide talks about required bracing.

 

[Glenn]

I’m certainly not going to argue with you, but page 10 of the awc deck guide talks about required bracing

I'm very aware of the AWC guide and it is also an illusion in regard to lateral loads. I am very aware of the assumptions they had to make and the limitations they had to create. I work directly with the AWC staff in charge of the DCA-6 for IRC development.

Tell me... what is the minimum design lateral live load? I'll wait... It's not even in the latest ASCE-7 It doesn't exist.

Testing nearly a decade ago proved that lateral live loads were a greater magnitude on decks than wind and seismic... yet we have no load to target.

How do you design a structure to resist a load that is undefined? How do you design a braced wall panel if you don't determine the width and height of the wall? How would you do that for a deck shape? I really suggest you attend my webinar. It might surprise you to how much everyone has been guessing about something that no one has an answer for.

 

[steveray]

There is a line there somewhere Glenn and we currently all draw it for ourselves....I am not going to make my customers get an engineer for an above ground pool deck, and the deck at the house should not be much different....Could I get to that point, yes, but not starting there...

 

[SDS]

it's a shame they didn't design those floor trusses with a shorter outer end-vertical and change that 2x4 lateral brace to an engineered rim board that the deck ledger could be attached to...I bet the mfg can provide a repair sheet to do it. Just need an engineer to size the rim board.

- Captain Obvious

 

[e hilton]

They could have, if they had been asked. The builder wanted the least expensive solution for the house framing, didn’t consider the future deck. Or ... we always do it that way.

 

[Glenn]

There is a line there somewhere Glenn and we currently all draw it for ourselves....I am not going to make my customers get an engineer for an above ground pool deck, and the deck at the house should not be much different....Could I get to that point, yes, but not starting there...

I'm definitely not advocating for engineers on every deck. It's why I work so hard to create standardized deck codes in the IRC. However, after over 20 years in the deck industry, from building to inspecting to making code to teaching, I can tell you a lot of building authorities, contractors and designers are drawing that line blindly and without any understanding. Thus... my webinar tomorrow... Understanding. Understanding that decks aren't as simple as we've been treating them for all time.

In this thread, many are advocating for engineering just to attach to the floor trusses. I on the other hand advocate for using the information from the industry association.