Securing existing deck against house 1

[miz0133]

During a home inspection, we have realized that the deck (attached) may not be properly secured to the house.

The joists are attached to a piece of wood (spacer board) with a hanger before it gets attached to the ledger. The ledger is attached against the wall with cement/mortar from what I can see in the photo - I have not seen such a joint before between a ledger and a wall. I wouldn't want to take the whole thing apart, but I am trying to find an easy way to properly secure it, which would then allow me to remove the 4th column next to the house.

http://files.engineering.com/getfil...65-91d4-995135cd7df9&file=20130820_183159.jpg

http://files.engineering.com/getfil...32-8ca2-5af752526a3f&file=20130820_183045.jpg

http://files.engineering.com/getfil...cb-88b2-536cd94afff8&file=20131001_080525.jpg

http://files.engineering.com/getfil...6b0-368720149ed7&file=IMG-20130930-WA0000.jpg

http://files.engineering.com/getfil...ed5-3ecc8913b941&file=IMG-20130930-WA0001.jpg

http://files.engineering.com/getfil...311-8295c26d2681&file=IMG-20130930-WA0002.jpg

 

[JAE]

Are you the homeowner or the engineer hired by the homeowner?

 

[ztengguy]

you could shore it, cut and attach a ledger board to the house, or you could place a header below it. Seems like an easy fix...why the questions?

 

[SteelPE]

Don't forget that the IRC now requires an attachment to the house to develop a lateral load 1500# at two locations (this is from my memory and may not be 100% correct). From what I remember, this is very difficult to do with a ledger making the option of adding a new header below and columns at each end more appealing.

 

[a2mfk]

I have the same question as JAE. If you are a homeowner, hire a structural engineer. Looks like you have a few things going on here.

My main concern is the spacer board between the hanger and ledger. Not sure why you would need those unless they really goofed and cut all the beams at the same time a 1/2" short. I would be worried about the cantilever action this creates in bending the nails. I also don't like the gap between the ledger and wall that is filled with foam. This also creates a cantilever condition in the bolts or lag screws that attach the ledger to the wall.

What is the wall construction, wood frame or CMU?

There is also a decently sized vertical/irregular crack in the stucco adjacent to the post, which may be the reason someone installed that post.

 

[miz0133]

I am the owner and the structural engineer.

I am not sure about the spacer board or the shims either, but the problem remains to make sure there is a connection between the joists and the ledger which is not clear to me, there could be a concealed type hanger (i.e. LUCZ simpson tie catalogues page 69) but I can not really tell.

Another solution could be to trim the shims around the joists and to add another face mount hanger (LU26 or similar), and then to achieve a positive connection by drilling lag screws through the ledger all the way to the rim of the house.

I just wish there is a way to tell whether those hanger are concealed LUCZ flange hangers.

 

[msquared48]

Do you have a metal detector?

Mike McCann
MMC Engineering

 

[miz0133]

No, have not used one of those before for this purpose - any recommendation?
Are those accurate?

 

[msquared48]

If you know how to use them, yes, they can be very accurate.

I have a rebar detector, and that could work just as well. You will have to distinguish between nails and the hangers, but the hangers, if present, should give you a larger area of a positive reading than the nails.

Mike McCann
MMC Engineering

 

[dhengr]

Miz0133:
I realize we are dealing with semantics here..., maybe to avoid the truth, you know, we don’t. You may be the owner, and you may be pretending to play structural engineer on this deck project, but the real question was, are you a Structural Engineer by formal education, and are you a Registered Professional Engineer, so you have a vague idea what you are doing? If you were a real engineer, you wouldn’t be asking the questions you are asking, in the way you are asking them. So, the question still stands, JAE was right on the money. You need more than a Simpson catalog to do this right. Anyone can slap a deck together, but a lot of them don’t even start to comply with the intent of the building codes, let alone the letter of the code verbiage.

That deck looks like a cobbled mess. And, you will have to do a little investigative work to understand what’s going on, if you weren’t the builder.
1.) Why is the ledger built in 4' lengths? What is it attached to and how? Why don’t we see any through bolts in the ledger? Do we see stucco over a brick veneer in the photos? Does the code allow a deck ledger to be attached to brick veneer?
2.) You have to dig deep enough so you can draw a detailed section through that bldg. wall; the window head jamb, the window header, the rim joist and floor framing, etc. It’s a fairly short deck span, but it does load the window header. Wishing won’t do the trick here, and concealed hangers don’t count unless you can prove they are there. But then, what are they attached to?
3.) Why are there different sized deck joists, and why aren’t they well seated in their hangers? The hangers will not carry their rated joist loads when they are nailed into the ledger through the .75" end shim boards (your spacer boards). Those nails aren’t acting in shear btwn. the ledger and the hanger, they are acting as .75"+ cantilevers btwn. the hanger and the ledger. What is their penetration into the ledger and their size (dia.)? What the heck was the original intent of those spacer boards, they just don’t make much sense?
4.) Is the ledger and deck properly flashed? What prevents water from getting behind the stucco below the ledger? Why remove that corner column, you’ll just be left with stucco to patch in an awkward location?
5.) The ledger should be mounted tight to solid wall sheathing and/or the rim joist. There should not be several layers of other building materials or void space btwn. them.

 

[miz0133]

Thank you Mike, that is a good idea, but I am not really sure how the metal detector or the rebar detector can tell that there is a concealed piece of metal behind a joist. If anything, it will probably detect the metal of the hangers on the sides.

 

[msquared48]

You know, if you cannot accurately determine how it is attached, I would temporarily add at least two additional columns under the ledger. I know you do not want to hear that, but a lousy look is better than a failed deck, and the personal liability that goes with it.

Mike McCann
MMC Engineering

 

[StrucPatholgst]

If I were to run across a similar situation in the field, I would recommend to my client (after assessing the structure visually, and speaking to the local construction code official) something to the effect that the ad-hoc hanger arrangement be replaced with proper hardware, including a new ledger board, if needed. Leave it to the contractor to perform the work. You don't want to accept liability for his work by spelling out how to shore it and perform the work, unless you get paid to do so.

If my client happened to be the contractor, I would (after careful review and field assessment) recommend something to the effect that the deck be shored and braced from below using Safway hardware in the manner I calculate and prescribe, that the deck boards above the ledger be temporarily removed, the joists trimmed to the correct length, the old hangers and spacers removed, and a new ledger laid over the existing, with through-bolt fasteners and hangers sized and installed as recommended by the PRDCG (with whatever ever local addenda that the local jurisdiction has added). In simple terms, get rid of the whacky ad-hoc shenanigans, and do it over properly. You'd only need to replace the existing ledger if it was rotten or not PT. Also, you can't use lag bolts on LU26's. I've been down that road. It's either nails from Simpson's published fastener schedules, or you defeat the product warranty. Or, if this is part of a real estate transaction and the other party and local jurisdiction accept it, you can sign and seal a modification drawing that supercedes the schedules, and take ownership of the liability. But that's typically not worth it, because the fees for such a thing rarely exceed $1000.

If my client happened to be the buyer, insurer, or bank, I would have no problem quickly finding and calling out this kind of improper fastener and hanger arrangement. It's always better to do it correctly instead of cheaply, because engineers like me will always call out the ad-hoc shenanigans, and recommend that it be done over.

 

[miz0133]

Dhengr:

Not sure why I would play to be a licensed professional engineer if I am not. In case you do not wish to provide your opinion, no one is forcing you to do so on this forum.
but here are some answers to your points below:

1- Are you suggesting I go back 20 years and ask the builder?
2- Ledger is on the back of the rim of the house. Wishing to know if concealed hangers were there is to avoid additional work, if I can't prove it, of course will not rely on it.
3- Again, this is the situation, next time I will investigate back by finding the builder who put it up 20 years ago. WHO KNOWS! again this is how the house was build, and I am trying to find a feasible solution.
4- There is a flashing on top under the deck - check the pictures again.
5- Stating the obvious.

 

[hokie66]

Based on the photographs, I agree with dhengr's analysis. But rather than digging into the wall, probably resulting in more disappointment, I would provide another line of post and beam support adjacent to the house.

 

[a2mfk]

Maybe I am misunderstanding something, but there are clearly hangers in the photos? They just appear to be nailed through a 1/2" or so piece of plywood (shims), which as I discussed above is a problem.

If you are a structural engineer and you go goofing around with repairs and they are not done right, and there is a failure- it will not work out well for you once someone hears about your qualifications. You have too many unknowns here. I would redirect my energy into sizing a new girder-beam and a new far post to go under there (from your pics there is a small space for a 4x4 between the slider and the window). And then I would focus on how to make it pretty for my wife to not complain too much.

If you figure out that very last part please share. That is much more of a challenge then some basic engineering and carpentry.

 

[TXStructural]

I don't see anything that would make me feel safe using the deck as it is. If it were mine, I'd shore it up and remove the deck board closest to the wall. From there I'd investigate the rim joist and the wall behind. I am not entirely sure that the wall behind doesn't already have water damage, as this is very common. I'd remove the cobbled rim joist and then, either a) if the wall is fine and the waterproofing looks good, install a double rim joist which fills the gap and supports the deck on the building frame, or b) if the wall and/or waterproofing is not good, clean and fix the wall, fix the waterproofing, patch the stucco, and make the deck freestanding.

 

[LittleInch]

To add my observations on this, I find there are a few vital missing pieces of information.

1) What is the wall made of? If it is brick you have to me a fairly simple solution to just drill trhough the ledger board and insert some large brass bolts at regualr intervals between each of the joists. My gues sis tha tthe ledger board fixings are hidden under the strange pieces of wood infront of the hangers.

If it's wood framed it gets a bit harder as you really need to find the main joints to attach the ledger board to.

2) Can you lift off the main boards or are they due to be replaced - 20 years in the open would do for most timbers and then you can remove the joints, rip off the ledger board and replace it with a thicker one ( to get rid of thos odd bits of wood at the hangers) anchored to the wall by things you know and make it one piece rather than the odd 4' bits of wood this one is made from and remove the post you seem to want to get rid of for some reason. I think you know this is the proper way to do it...

3) If it's lasted 20 years, the ledger board is clearly attached to the frame of the house somehow - the key issue being you don't know size, condition etc neither do you know what the hangers are attached to the board with. Galvanised screws / nails might last 20 more years, but steel nails / screws....

4) Try the "Fat Guy Test" - Invite some substantial sized people around for a few drinks and encourage two or three of them to stand in one place on the deck whist someone watches below to see if the planks move.... If they don't you've proof load tested your deck and then just make it an annual event. Catastrophic collapse would seem unlikely and given the ledger board is actually in several pieces they shouldn't fail all a tthe same time.

Just my thoughts...

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[XR250]

@Littleinch - Fat guy test - really? What if it does not pass?

 

[LittleInch]

No more Fat guys.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way