Re-use or replace existing joist hangers

[gte447f]

See attached detail. This is a work in progress. I am designing a repair plan for an existing, residential, exterior deck. The columns are rotted at the base and the edge beams are under sized, among other problems. This is a large, wrap around, 2-story deck, that will be very expensive to replace, so the owner would like to repair instead if possible. The joists and most of the deck boards are in good shape. The plan is to shore the joists and replace the columns and edge beams. My question is about the joist hangers at the edge beams. Is it feasible to disconnect the existing hangers from the edge beams and re-attach the same hangers to new edge beams with new fasteners, or is it necessary to replace the hangers with new? I'm sure it is probably better to replace the hangers, but is it possible to re-use the existing?

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1724003660/tips/working_edge_beam_section_yv7qjf.pdf[/url]

 

[lexpatrie]

I doubt the hangers are all that significant in terms of cost, and health, safety, and welfare don't include cost anyway.

Are the hangers of the correct type for exterior exposure, even? I'd expect these will be damaged if ordinary care is used in removing them.

Not that I've looked at the picture.

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[gte447f]

Lex, the hangers are standard galvanized hangers used inside and/or outside. I don't think exposure is an issue. They appear to be in ok condition, no corrosion. The nail heads do show some corrosion. There will probably be about 150-200 of these hangers, but I am not that concerned about the cost, although since you mentioned it, I did a quick Google search, and I was shocked that basic hangers appear to be only about $1/each. I can't believe they are actually that cheap. Mainly I was just trying to limit the scope where ever possible, because as the scope creeps up, at some point it begs the question of why not just tear down and rebuild the whole thing, which we are trying to avoid. I guess joists and deck boards are the majority of the cost, so if those can be preserved, then everything else is fair game for replacement, including these joist hangers. I think I am talking myself into specifying replacement of the hangers with new.

P.s. When I use the "Image" button in the ribbon, it uploads the the file to the cloud and inserts the link in my post. I don't know how to insert an image inline. Can you explain it to me like I'm in kindergarten?

 

[EdStainless]

Aren't there double galvanized (actually just double weight of Zn) hardware intended for outdoor use?
The same goes for any nails or screws used.

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P.E. Metallurgy, consulting work welcomed

 

[phamENG]

gte - I'd be concerned both for the hangers themselves and the joists. Most of the basic ones do depend on toe nailing the joist through the guide holes in the hangers. By the time you rip all those out, how much 'meat' will be left to refasten?

If they are still in good condition with no apparent corrosion, then I'd be inclined to tell the contractor to take extreme care in disassembling that portion of the structure, and inspect what's left when they feel they've done enough. You may need to replace some hangers, and maybe even a few joists.

 

[Tomfh]

Replace them. Reset their lifespan.

 

[gte447f]

I have decided to specify replacement of the hangers at the edge beams. Now I just hope the hangers can be removed without doing too much damage to the ends of the joists.

 

[LittleInch]

The fun will be how those existing hangers are fixed tot he existing edge beams.

Are you then sistering two edge beams as new ones?

YOu probably need to have some sort of plan B for when the end of the joists which you can't see inside the hangers turns out to be missing / rotten?

You can load pdfs into the image, but they don't load as images. Use jpg files instead.

Like this.

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[RPGs]

Maybe you can add another new ply to the inside face of the perimeter beam if deteriorated joist ends need to be cut back after hangers are removed.

 

[phamENG]

I'd be tempted to keep the face the same, but have them cut 1.5" off of the joist and just deal with the problem up front. Then you don't need to worry about torn up joist ends or water damaged joist ends that the contractor ignores and covers up before you an see them.

 

[gte447f]

LittleInch, thanks for the heads up on posting image files instead of pdf's. I'll try to remember that next time I need to post a sketch.

The existing hangers are just face nailed to the side of the edge beam. The ends of the joists are in generally good condition. I have confirmed this by inspection. I am not sistering the edge beams, I am removing and replacing them. Since I have decided to remove and replace the hangers with new, the repair sequence will go something like this: the joists will be shored in place; the joists will be disconnected from the edge beams by by removing existing hangers; new edge beams will be installed; and the joists will be reconnected to the new edge beams with new hangers.

I just looked back at some site photos and it looks like most of the existing hangers only have nails into the edge beams. All/most of the nails into the joists are missing/were not installed. That should make removal a lot easier, and it means no reason to consider keeping the hangers, since when you remove the nails from the edge beam the hangers will basically fall off the joists anyway without any nails into the joists.

 

[gte447f]

Well, I was going to add the new ply to the outside of the edge beams, specifically so I didn't have to mess with the joists, but if the hangers are going to be removed anyway, and the ends of the joists are going to be accessible, then maybe it is better to cut the joist ends back 1.5" and add the new ply to the inside of the edge beam. I think outside is better, because it's less work, if there is reasonable certainty that the joist ends will be in good shape.

 

[LittleInch]

My point was how are you joining the now two ( was one) edge beams together?? The hanger only acts on the inside beam unless you really work at tying the two together no?

My worry is still rot or damage to the end of the joists you can't see until you remove the edge beams. Hopefully the joists weren't toe nailed or screwed in from the outside of the edge beam?

Are your hangers only going to be attached to the side of the edge beam as you show or actually hanging from the top edge? Most look like they are just attached to the edge alright. Nails? screws? Bolts?



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[gte447f]

LittleInch, I appreciate your questions.

The 2 plies of the new 2-2x12 edge beams will be fastened together with 2 staggered rows of 10d threaded nails spaced @ 16". This is pretty standard procedure for residential decks. I don't know if it checks out according to a rigorous calculation for load distribution between plies, but I know it will be fine based on empirical experience. As I said its pretty standard. Also, these joists are only 8 feet long, so 4 feet of tributary load going to these beams is not much.

The new hangers will be face mount hangers fastened to the inside face of the new edge beams with face nails. I don't like joist hangers with "double shear" toenails, and I don't like using screws when nails will get the job done.

The only real "issue", as several including you have commented, is the condition of the joist ends. I am confident they are not rotted. I can tell that much. Whether they will be damaged during the disassembly of the edge connection between joists and edge beams, I don't know. At this point, I am of the opinion that most will be fine and if some are damaged then it is what it is and it will have to be delt with. We can't always work miracles.

 

[lexpatrie]

If you are cutting pressure preservative treated wood you're supposed to field treat the ends. Greenheck or similar. If it's Western (DFL) I'm unsure if this will actually accomplish anything as DFL resists "wetting".