Contractor Talk - Professional Construction and Remodeling Forum

Contractor Talk - Professional Construction and Remodeling Forum (
-   Construction (
-   -   Steel Deck Beam (

Steeling4Bucks 12-23-2017 03:39 PM

Steel Deck Beam
I've been reading old posts and I think there is a wealth of knowledge here. I have a question that maybe someone can answer? I have 16AWG, 2.5" flange x 16.5' long joists on-hand. I would like to build a deck that has a 20ft span and is 16.5' deep. I can use 3 posts (10ft span per). Here is the question, do I need to make a double beam or is a single okay? Am planning on setting the beam at 12ft. Also, could I somehow bury the beam in the decking? Notch the steel post and bolt through? The view is great, but the added depth from the beam will block a large portion of it at 16.5 feet. Can anyone share their thoughts on this? I've never done a deck with steel before, but have framed plenty of walls with it. Thank you, and Happy Holidays!

Steeling4Bucks 12-23-2017 03:50 PM

I should probably clarify something. The building itself is steel. The width of the deck (20ft) and depth (16.5ft) will be approx. 10' off the ground. A patio will be poured later. Using 6" diameter round pipe (1/4" wall) for posts, which will end up about 17' tall. I want to attach shade sails to the building later if needed to make the deck comfortable in our weather. The long posts will also make attaching wrought iron railing simple and strong.

Fouthgeneration 12-23-2017 07:03 PM

2.5" width X "what depth in inches":whistling x 16.5' length 16 AWG what shape, and simple corners or ribbed????

what type of tension connection is to made from the ledger 'board' to the existing house, is the house floor & wall strong enough for the added wind and live loads?

What kind of lateral (x or K bracing...or whatever) between the posts parallel and perpendicular to the house wall???

You could push the cross beam out in to the edge of the deck so it forms a ledger beam and the bottom of the rail system.

Your wind sail will double the size at least, of all the structural components, including the weight of the poured footings.....unless it has some reliable tear away if it isn't rolled up for storms.

Steeling4Bucks 12-23-2017 07:31 PM

I'm sorry, I completely forgot about the web depth, which is 8". The joists are simple, no ribs. I would use a 2.5"X8" track to make the beam. I have 8" wide 26AWG matching trim for the outside already. As for the sails, they will break away if I tie them with nylon rope, but that's not a concern, really. I can live without them. Thank you for responding!

Steeling4Bucks 12-23-2017 07:36 PM

Since the interior walls are open, I was going to add 4"X4" 1/4" wall tubing to support the ledger, though there are 5 4X4 16AWG tubular members in that wall already. I will bolt through the existing interior ledger after removal of the siding. I can add whatever else you think should be done. Does that sound a bit more complete?

Fouthgeneration 12-23-2017 10:58 PM

Checking the Dietrich brand joist tables for 2.5" x 8.00" 16 gauge/54mil regular 50 Kpsi steel, you are fine to 19.2" spacing if I 'm reading the correct line, there is no 19.2"spacing chart, but 16" spacing gave ~22' span for 10 dead 40 lbs live load at L /360 using their notes for construction... and 15' 11" span capacity at 24' C to C spacing.

the center post would carry 50% of the outer 8.25' x 20' deck load, 82.5 sq. ft. x 40 lbs = 3300lbs, x a 4 to 1 safety factor = 13.2 Kips load on the center post 6" x 0.250 HSS tubing at 11' to footing plate, will fail ~ 82.1kips ASD table, 123 Kips LRfd table

beam design 9'- 9" to center span... 3300 total load at ~330 lbs a foot

Any 8" C channel would work, 8.00 track welded to a joist(s) would be stronger then two tracks tacked together. there appears to be flange over loading with 16 gauge track....

No snow load for Tucson...

What about corrosion?

Steeling4Bucks 12-24-2017 12:22 AM

Corrosion should not be a factor here. If I use all steel, and since we have almost no rain and pretty clean, dry air, I can't see a reason why it would be problematic. Do you think that I need to go 9'9" instead of an even 10'? I had considered making a double beam with two tracks and two joists anyway. I'd love to bury it and streamline the look while saving the views. I could shorten the depth to 12' to offset that concern. I just hate to build something so nice but have it end up so small. Not great for entertaining, but safety first, right? I should mention that it will be sheeted with 3/4" marine plywood and PVC decking over that. I appreciate your help and welcome your advice. My strong suit is electrical, mainly controls.

Steeling4Bucks 12-24-2017 12:32 AM

BTW, it appears that steel pipe is 5/16" wall, not 1/4". I don't know if that is standard product or not. I had considered filling it with concrete for rigidity. It will just be a pain to fill at that height.

Pangdev 12-30-2017 01:15 AM

Why not ask an architect?

Steeling4Bucks 12-30-2017 10:06 AM

Around here, once they know where you're building, the price goes up enormously. I did ask an architect, though. I was told that you cannot use light gauge steel for horizontal structural members. You must always use beams per national code. If that were true, none of the steel framed decks would be legal. I figured my next step would be to go to the guys who do this every day and manage to construct decks that don't fall down. If you know of someone who is willing to discuss this, please let me know. Thank you!

Fouthgeneration 12-30-2017 01:49 PM

RE:9 '-9" instead of 10' foot center to center, Elevation column spacing on long face away from house. ~2"x X rim joist, 3 x 6" of 6" Diameter columns corner, center, & far corner, far end rim joists, adds up to 18" leaving two beams Spanning two actually 9'-3" openings...... the 9'-9" was conservative....

If you water your yard, it isn't super dry anymore.... hot tub? spa, swimming pools? Car wash every Sunday?

Rust NEVER sleeps.

Steeling4Bucks 12-30-2017 04:50 PM

This is where rust goes to vacation. Bare steel will surface rust, but that's about it. You can hand sand a car from 1929 and it'll shine right up to bare metal here. No pool, spa, plants, or car washed nearby. This is the desert. It only rains about 15 days per year. I reread your original reply. Thanks for the clarification and your help!! Happy New Year!

Steeling4Bucks 12-30-2017 04:55 PM

FourthGen, would you put a rim joist on each side of the post to allow for a 2ft overhang? Would that add any appreciable strength to the deck?

AustinDB 12-31-2017 09:28 AM

I have the bed from a 67 chevy long/stepside sitting in a yard in Tucson that has the original light rust and patina that comes from that climate. Love driving around Tucson and seeing the old original cars that have lasted because they don't rust away like they do back east. No longer have the truck though :(

Steeling4Bucks 12-31-2017 05:49 PM

That is true. I had a 1954 Willys Wagon that was still perfectly fine despite not having any paint on half of the body parts anymore. Corrosion is not a big issue, which is why the government stores all their aircraft here in the desert.

Fouthgeneration 12-31-2017 07:51 PM

You'd lose the use of the center column for the center of the long hand rail....
But the FLOOR would be a lot stiffer with the columns at ~13-9" from the ledger board, I though you were against the beam blocking the view of the lower house window(s)

As a practical matter, the cantilevered floor deck would require a drop beam construction, I' d have the beams run on both side of the columns with blocking as needed, Don't forget the blocking on the deck joists @ about 56 inches and 112 inches if cantilevered at 168 inches....

JLC had an interesting way of installing a rubber roof mat to dry in the under deck area, maybe switch to white EPO roofing instead EDPM roofing material.

Steeling4Bucks 12-31-2017 09:28 PM

What if the deck is not used past the columns? Maybe I should sketch something up to show this a bit better? I'd like to have 18"-24" of overhang when finished. If I can bury the beam and simply add the overhang outside the walkable edge, then I can use the columns for railing, can I not?

Steeling4Bucks 12-31-2017 09:29 PM

I do like the roofing idea, by the way, thanks!

Fouthgeneration 01-01-2018 07:25 PM

It would look a little unusual, but you could still poke the column through the deck to tie to the center post. (you'd have to step around the 'stub' wall/rail between the column and the railing).

Some people build a "bench seat" rail system...

Steeling4Bucks 01-02-2018 01:29 PM

That is how I had pictured it being done originally. I just wasn't sure it could support the weight. I would use wrought iron railing between the columns. A bench seat type system would be good, too. If you think the dropped beam gives me so much more strength, then I should consider that over the views, though my wife will probably make that a big deal.

All times are GMT -5. The time now is 02:35 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.