Damaged Roof Decking

[SteelPE]

I have a project that is currently under construction where the roofer decided to use some sort of cart to haul around his roofing material. In the process of moving his roof material around he ended up damaging the roof deck. The ribs of the decking are all dented and dimpled where the wheels came in contact with the deck. I has warned the GC about this issue prior to construction and told them that if it happened on this project repairs would be needed.

The project team has been in contact with the deck manufacturer and owner and we have come to agreement that 60 sheets of roof decking need to be repaired. Now come the method of replacement which I need to agree to. Currently, to expedite the installation process, the erector utilized Hilti power actuated fasteners (PAF's) to "shoot" the deck to the roof joist system. Removal of the decking will involve grinding of the PAF heads.

Now comes the contentious part, the GC would like to nest the new deck sheets into the existing and not fully remove the existing damaged decking. On the surface this seems like a good idea.... however I do have some concerns

1) Will the decking profiles actually nest together. Currently the roofer has this decking in stock but we are not sure of the manufacturer..... and therefore, it's highly likely the decking will not properly nest
2) The damaged ribs may prevent the new decking from nesting properly
3) When it comes to fastening this decking to the existing roof joist system, there is a potential for the fasteners to have to go through upwards of 4 sheets of deck (at the location where the deck sheets overlap (This could be mitigated though by staggering the new sheets such that we only end up going through three layers of deck with new fasteners. My current plan has them attaching the new deck to the existing roof system using 5/8" dia puddle welds.

The GC said that they can handle items 1 and 2 in the field (that is, reject the deck if it has to be forced into place) however, they are looking for new fastening requirements from me. Is my concern about puddle welding through 3 sheets of deck unwarranted? Should I be allowing them to use PAF's.... or should I be forcing them to completely remove the existing sheets to install new sheets of deck? I'm torn between all the options here.

 

[XR250]

You could use Tek5 screws. They should go thru 4 layers. How would PAF's work? Trying to hit the joists at this point would be tough and I don't see how they would work in just decking.

 

[phamENG]

How high is the shear demand? If we're in an area of high shear where we need every little bit of capacity out of the connections, I might lean toward tearing it out. But if you're in a low-ish shear zone and demand on the connections isn't that much, I'd look more at PAFs. Maybe go with some that are slightly longer if needed to ensure it fully engages the base material. Are you going into bar joists or beam flanges? If bar joists, I'd be shocked if you couldn't go through all of them. I'd look for a test report with a secondary thickness equal to all 4 plies of deck, though, and make sure the fastener can perform with that much of a gap between the head and the base material.

 

[jerseyshore]

I don't mind the idea of new deck sheets over the existing. I've done that before. You're right about them needed to sit nicely though.

Attachment should be doable with the welds or longer screws that XR250 mentioned. It would be like attaching really heavy deck (assuming the two sheets are sitting nicely together). I also agree that the Hilti PAFs are a longshot to work this time around.

 

[SteelPE]

I asked the question about the location and the GC said that it's random locations, so we would have to assume that it's at location of highest demand for the type of decking damaged (we had 18ga and 22ga decking and only the 22ga was damaged). Based upon my calculations done over a year ago, maximum demand for the 22ga decking is 427plf.... but the fastening pattern was selected for efficiency.... so yes, shear demand could be high.

 

[phamENG]

(For what it's worth, I don't think I've ever spec'd pins for deck. Everyone around here prefers welds. I have done screws a couple times, though, for special projects.)

 

[jerseyshore]

I usually spec welds but tons of people these days want to swap out for the Hilti fasteners. Fine by me. The Profis DF software is great for that. See if they have anchors long enough that meet your capacity.

 

[SteelPE]

I don't specify PAF's either..... My drawings show welds and the erector always comes back and asked for PAF's. After being onsite while they were fastening I can understand why. It sounds like they are nailing down a wood floor in term of quickness.

I suppose I could tell them to remove and replace certain areas of decking where shear demand is high and then tell them they can nest the deck towards the middle of the building where shear demand is low.

 

[Once20036]

Every time I`ve encountered this situation in the past, I`ve insisted that the GC work with the deck manufacturer to develop a signed and sealed solution, and submit their proposed work plan to me for review and acceptance. Let them go on the record stating that the proposed repair has no impact on the gravity or lateral capacity of the system.

If it's not suitable to the manufacturer (an upstanding member of SDI, I assume), its not suitable to me.
Why accept the risk that's inherent in your uncertainty?

 

[jerseyshore]

Because even though that sounds good the reality is Vulcraft is going to turn around and say we don't detail repairs that's for the EOR and the owner is going to say we need an answer right away because the contractor is being held up by this.

These situations usually come down to figuring out a solution to move things along or just can't do anything about it you'll have to redo it.

 

[Once20036]

I understand the concern, but I have gotten support from the major manufacturers in the past.
If you haven't reached out to them yet, give it a try.

 

[Brad805]

If the pin heads are not ground off they will not nest well at all if you have anything more than a 36/4 fastening arrangement. If the pin heads are removed they will nest if the same mill rolls the new sheets. We have seen cases where engineers have used multiple sheets to deal with snow drift loads.

 

[Aesur]

I'm with Once20036 here - make it the contractor problem to either find a sealed solution from an engineer or pay you to come up with one. I would look at screws personally and not even go down the rabbit hole of PAF's with the unknowns here. If they want PAF's then have them submit a substitution request to your designed solution.

 

[SteelPE]

In the end, I decided to have them fully remove and replace sheets where the shear loadings was high (perimeter of building). In the areas with lower shear (middle of building) I allowed them to nest the new decking into the existing.

 

[jerseyshore]

And the fastening for the overlapped deck?