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Community and Q&A

Steel Deck Framing

joenorm | Posted in General Questions on

With the price of lumber and the fact that I never enjoy working with PT lumber I was wondering if it makes sense to build a second story deck frame out of steel.

Is anyone doing this? My local lumber yard has very little knowledge of the parts but can get a certain brand. They say nobody is doing it around here. Maybe it’s too expensive? Maybe nobody wants to learn a new product? Hard to know.

Does it make more sense from a green building perspective? Avoid the chemicals and the future landfill? I don’t know prices yet so that of course will be telling.

Any thoughts? Thanks

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  1. jadziedzic | | #1

    When I built my last deck a few years back the Trex folks were offering free design service for their metal deck framing system, although I don't see any traces of that on their Web site. In retrospect, had I known how much time I would spend planing down pressure-treated wood joists so the decking wouldn't look wavy, I would have gone with that system. There was an article in Fine Homebuilding a few years back that showed how you could "design" your own system using off-the-shelf metal framing components for drywall; here's a link:

    Back when I considered it steel was more expensive but did require fewer beams, had longer joist spans, etc., so the cost differential wasn't all that bad. Now with the crazy prices for building materials I have no idea what the cost would be.

  2. Expert Member
    Akos | | #2

    I have a 3rd story deck framed with CFS. There are a lot of things about working with steel that is much easier and some things that are pretty annoying.

    If you do the design up front, you can get all the material made to your exact length from the supplier at no charge. This means there is almost no cutting on the job site and very little scrap. After a 800sqft addition out of steel, the entire scraps was a couple of off cuts of track and bridging straps.

    Since everything is pre-cut, you have to do a bit of sorting but than it goes up very quick. The only tool you really need is a cordless impact driver and a chop saw. Not as quick as framing nailer but not too bad.

    It is very easy to build up larger cross sections out of combinations of studs and tracks. Since all these pieces are very light, you can build up a very beefy beam without needing any heavy lifting. They also come in a number of gauges and flange widths, so you can get away with much smaller cross sections. Generally an 18gauge studs is about the equivalent to the same size 2x lumber.

    The annoying part is all the specialty screws you need. You can built most things with a handful of self tappers. Attaching any wood to the steel requires special screws or pre-drilling the wood. You have to make sure that you know what fasteners you need and get them ordered as most are not stock item at a box store.

    Since the steel comes galvanized it holds up to weather pretty well but you still have to protect it. It also doesn't look the best left bare so the deck needs to be wrapped on the bottom side as well.

  3. joenorm | | #3

    Thanks. I also need a beam to span pretty far between posts. Could be between 16'-18', I haven't worked it out yet. I wonder if I could built that beam up of if it would require a specialty I-beam.

    1. Expert Member
      Akos | | #6

      18' can be clear spanned with standard joists, off the top of my head it is a 16 gauge 12" joist.

      If you do need a beam, it is very easy to build one up from pieces. No need for a steel I beam. Look at some options on P34 here:

      1. joenorm | | #7

        Yes, I found a span table for Fortress products and it looks like spanning up to 20' is pretty easy. I'd be tempted to use the steel beam to get the span and then use PT wood as joists to save money.

  4. jadziedzic | | #4

    Keep in mind all cut edges of the galvanized steel pieces need to be coated with a cold galvanizing "paint" otherwise they'll rust.

  5. charlie_sullivan | | #5

    We did it with the Trex steel components. The lead carpenter learned pretty quickly how to work with it; his helpers were slower to catch on. We have white cedar posts and decking and a steel frame, so no pressure treated lumber at all. The only thing I don't like about it is that when apples fall on it from our apple tree, the steel resonates and we hear a bonging noise.

  6. graham78 | | #8

    Ive used Fortress framing on a a few decks and the framing itself becomes one of the shining stars of the deck. It looks awesome. And Trex Steel as well, but I believe the Trex steel framing is no longer.
    Yes it cost ALOT more than PT. And getting a few m0re pieces that you screwed up on was a big hassle. The Fortress rep told me a few years ago that it added 10$ per sqaure foot on the framing portion. The Fortress Ledger is system is really cool.
    I don't think steel gets alot of green points over wood?

    Ive chosen to use PWT treated LVL as a middle ground between the cost of steel and PT. It is fun to work with, straight, and you can usually downsize the lumber which makes it lighter (huge). Might add about 4$ per square foot.

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