Screw or weld steel deck

[vmirat]

I was in a meeting the other day and mentioned that I would prefer to have the steel roof deck screwed instead of puddle welded. The EOR stated that he had poor experience with screwed decks and prefered welding.

Attached is an article which argues for screw attachment. What is the consensus out there?

 

[SlideRuleEra]

The experiences of the article's author match mine, word for word. Designed a roof for an open-air rail car repair facility to be constructed by the user's. Although the welders were expert at the heavy welds need to repair rail cars, they had a difficult time mastering the puddle welds for the roof decking... and, that decking was relatively "thick" to withstand wind uplift, etc. Since this was an inhouse job we had the means to make it come out right, but IMHO, screws are the way to go in a typical specification.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[mmillerpe]

I typically use, and appears to be the most common locally, deck welded to supports. with screwed sidelap fasteners. Where the deck is going to be exposed I have been specifying Hilti X-EDN or X-ENP products depending on the application.

 

[JedClampett]

Each has their problems. It seems counterintuitive, but the contractors say welding is cheaper.
You have to be careful with the self tapping, self drilling screws with regard to the support thickness. An average flange (say 1/2 inch thick) might exceed the thickness that the screw can penetrate.
On the other hand, spot or puddle welds might not fuse to thicker flanges either without preheating.

 

[WillisV]

I have moved away from welding entirely due to many of the issues pointed out in the article and use Hilti pins and sidelap screws. This is even more practical on highly pitched roofs where puddle welding is very difficult.

 

[ToadJones]

Our field guys seem to prefer screws. We have been using the type that requires pre-drilling, and they still prefer them to puddle welds. We also have been using epoxy paint on our latest job and it seems to offer another small obstacle to puddle welding.

 

[paddingtongreen]

This is one of those areas where I like to let the erector use the method he prefers, I found that they picked the method they did best. Others are for shop connections to be bolted or welded, and which bracing members other than angles need "draw".

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[Gumpmaster]

We almost always use shotpins with crimped sidelaps (ASC Deltagrip or Verco Punchlok). They just seem to me to be very reliable, easy to inspect connections. For us in seismic country, they're also ductile & Strong.

Does anyone else use crimped sidelaps. Much faster than welding, no consumeables. It seems like a win-win to me.

 

[rustyjames]

Our company hasn't welded deck in years, it's all shot down with a pneumatic system. The pins are quite expensive.

 

[Ron]

I prefer pneumatic or powder actuated fasteners over welding.

If you inspect those welds in accordance with AWS requirements, many of them fail. I've personally inspected hundreds of thousands of square feet of decking, both welded and mechanically fastened with a variety of methods. If you hold the subcontractor to the requirements of AWS D1.3-Structural Welding Code-Sheet Steel, he will likely fail. First, most structural welders who have certification, are certified to AWS D1.1-Structural Welding Code-Steel. For welding sheet steel (e.g. decking), you must be qualified to AWS D1.3. That's not so bad if they only qualify to one thickness, but keep in mind that when installing decking, you can have up to four thicknesses to weld at once...ends of two sheet, lapped at sides in same location...happens all the time. That qualification condition is not easy, but most inspectors fail to ask for it...it is a code requirement in the US.

Pneumatic and powder actuated fasteners are a bit simpler. The inspection is also straightforward.

 

[hokie66]

In the old days (1960's), we only had welding. It wasn't a very good solution then, and wouldn't be now. Either screws or shot fasteners will do the job. Shooting requires more attention to safety, as the nails will go straight through if they don't hit the joist.

 

[rustyjames]

The PAT will shoot it through the deck if the joist is missed, but the pneumatic will not; another good reason why it's the preferred method with most contractors.