I’m redoing this thread which I began a few weeks back.
I’ve gotten a bit further and now am running into some roadblocks.
My specifics are: No more than a 270 degree spiral, going around a 16″ square brick column (which the BI tells me was built around a 4×6 wimminized 10′ post sitting on its own footing, brick placed around it for looks after the deck was built – voids not likely to be filled). 120″ from floor to floor (I mean deck). The existing straight stairs has 15 treads with 7.5″ risers.
The visit with the BI took quite a while, as we examined the code books and my plans closely. He tells me that theorically according to code, my plan will work. That the real question lies in how the structure is assembled and engineered.
The decorative iron shops about town that I’ve been interviewing are freaked about my plans. They never have seen or built one with 18 degree intervals. 18 times 15 = 270. The BI says the code reads that 12 inches from the inside stringer, the tread must be at least 7.5 inches. My drawings have it at 7.75″.
What I get from discussing it with these guys is they buy kits from someone and adjust them to fit. What I got planned is not a kit. It’ll probably have to be built from scratch.
So’s I contact Denver Iron Works. They’re three weeks out from even talking to me. But they will accept my plans prior (but won’t look at them for the 3 weeks).
But the real issue: I can make pretty drawings, but I ain’t no structual steel engineer or designer. The closest I ever got to a welder is watching my Daddy make sparks.
The loads, spans, railings, connections – I got no idea. the Iron guys are gonna want more than my simple bozo drawings.
To whom would I turn for the design and engineering work?
Replies
From their website it looks like Denver Iron Works would be a good choice. Can they provide the shop drawings to fabricate? Otherwise contact a structural engineering firm that is experienced in stair work. My company is much like Denver Iorn and we detail shop drawings for almost every job we do. If the material sizing is not given to us though, and it isn't a typical project that experience tells us what to use, it is run through an engineer. If Denver doesn't work out for you, search for another fabricator in your area on http://www.nomma.org website.
Sounds like a fun project, post photos when it is done.
According to that website, the closest guy to me is 75 miles away. Which tells me all the ones local don't belong to this group.
Since we last talked, I have found a local structural engineer that says he can help.
So's he calls today and says, he doesn't know... Apparently, he's stuck on the ability of the fabricator to roll a strong enuff channel to a 270 degree 10' long, 24" diameter and then satisfactorily attaching it to the deck. Tells me he's been calling shops in St. Louis and Kansas City for advice and they sound pessimistic.
Refresh my memory, is this your area of expertise?
Pete,
Not an area of expertise, although I have been involved in steel stair assemblies that were 'called out"on my inspection as "appearing to be inadequate or incorrectly fabricated" on the jobsite.
An engineer had to be found that specialized in stairs to render an opinion that forced the fabricator to send men and machines to make the fix. That came via the architects office...I do not know the name. The structural steel engineer for the building refused to render an opinion and had no references...it seems that an engineering speciality in stairs, other than standard, is a rarity.
There were three parties that had "bad gut feelings" as to the stairs delivered and assembled on site. The iron workers, the job super ( a certified welder) and the on-site inspector (myself).
It took months of wangling and three week-ends of 24 hr shifts of three men from the fabrication shop(non-union) to make the corrections on the stair tower stairs. Not a winding stairs.
Trial by fire....but no expert!
...........Iron Helix
i think you are making this harder than it is... I've only built one steel spiral stair... but i'm a pretty good fab (steel) guy...
since spiral stairs arounf here aren't really "code" ie: can't be the only means or egress... but at least here the rise can be up to 9.25 inches... which would give you 13 rise and 12 treads...
it will be alot stronger if you incorporate the hand rail into the design...
pretty sure i could start by welding up all my treads use'n a 16" square template on my welding table... I'm make the 16" sq rotate and mark it off...( use'n an 8" rise that would give you 14 treads and 15 risers) looks like about 18.5 degrees so every small end of your treads could /might be different to fit right to your column... the large/wide end would be built just like any other spiral... i used 3/4 sq tube for my outside balesters... these catch the back side of the tread below and the front of the upper tread tie'n them together (take this 3/4" into account in your 270 degree swing as this will add to the outside traval of your stair) ie: rotation... ask me how i know this on a 22 rise 360degree stair i picked up about 15" ....
pretty sure for the inside "stringer" i'd just fab it in place as stacked the treads... with a 10ft piece of 12x12 1/4" wall sq tube cut into 7 3/4" slices... i'd just cut them to fit around the post one step at a time... you'd prob only use half of each slice on each rise...
i formed my hand rail in place use'n 3/8 round rod... i just kept adding rods until i got the hand rail i wanted... lots of welding and grinding but it feels and looks good.. and i had to "form" it in place so it was the only way i knew... i used the same rod to wrap the stairway every 4" ( the balasters that connect the treads acting as the form)... for the handrail after the first 2 rods were welded to the balasters (inner and outer) i then cut the exess 3/4" tube off use'n the 3/8 rods as a guild...
sorry if this confused you... :) but pretty sure it could be site built by a pretty good fab guy... I'd only prefab my treads... and slice my post or rethink'n the sq steel post slices..... you could use 8" flat stock 3/16 -1/4" thick and use a press brake to bend the 90's that would go around the corners of your column...
i'm slow... but think i could build it 4-6 days...
p
For sure, an engineer specializing in metal spirals is a rare cat.
I believe it can be done, if the right people get their heads together.
I think I'm gonna have my engineer guy draw up a prelim with him marking out the areas of his concern. I'll then take that prel to a couple of fab shops and ask how they would / could build it to satisfy the engineer basd upon their experience.
I don't see how I could do this right without incorporating the railing into the whole thing. I then want to continue the same railing for the rest of the deck.
I really appreciate experts of yours and Iron's caliber chiming in.
I don't fully understand the part about going around the brick column, but anyway, I had a basic set built recently and it came out very nice. As far as engineering goes, the city had had a "standard plan" for basic residential spirals which is engineered and if your parameters fit within the limits, you pay for a copy and attach it to your plans.
First off, forget about any of those kits. They're pretty weak and nowhere near the strength and quality of a site-built set. The shop that built mine has done them enough that he stocks the treads, so there was really no option there, but it came out exactly how I wanted anyway.
The railing is made from rolled steel tubing that they have rolled to the diameter of the finished stairs and then streched to the height. It's brought on-site already formed and the fabricators trim it and tweak it into place.
Here's a pic:
The part about "going around the column" means that where your post is your picture, mine has a 16" sq. brick veneered column. Inside the column is a treated wooden 4 x 6 simpsoned to a concrete sonotube footing. There are 3 other matching columns holding up the deck. So's I cannot really take one off and replace it with a steel pole.
Imagine a 24" diameter pipe instead of a 4" pipe as yours. I'm looking for someone to engineer and fab me a 270 degree stair way that would spiral outward from that pipe. Why 24"? That pipe would slip around the column without touching at that size. Perhaps after, that pipe would be cut to become the inside stringer.
So's that's my picture.
As I sit now, I'm gonna have my engineer draw up a preliminary drawing, and make it up with comments about his concerns. such as, "Is this metal thick enuff at this point, What's the best form of connection to the deck, The intersection with the floor? Etc."
I'll then take that scratched up drawing to several fab shops and ask them if they can build the thing to solve the engineer's concerns.
Then I'll take those suggestions back to the guy and have him consider incorporating them into the final shop drawings.
i was think'n hug'n the brick column... thats why i said the flat stock... but... consider this... find a piece of 24" pipe... (most of the big sign shops might have a piece... i have one at least 14ft out in my lot now...) build the stair around it... then with a plasma cutter cut away what you don't need... you could just keep the spiral... or you could get artisic and have an inside balaster/top rail... which would all be part of the 24" pipe... just cut out what you don't want... ... it could turn out really nice and be "ART"...
gave me an idea for my next set...
I'd sure float that idea past the fab guys...
p
Haven't got to the fab guys yet. But I did suggest practically the same thing to the engineer and he said he was having a tuff time trying to envision how it would then anchor to the deck...
Well, getting him to put something on paper will get his thoughts tricklin'. Even if it doesn't, I'm sure the fab guys would know.
he said he was having a tuff time trying to envision how it would then anchor to the deck...
ummm maybe a bracket welded to it?
maybe it's a gift... maybe it's a fault... but i can visualize exactly how i'd build it.....
I think it'd be a cool project and .... use'n the 24" pipe an easy build.... pretty sure i could sketch it... no way i could draw it... and no way i could engineeer it... but i know it'd be safe ... over built and would hold up...
you need someone who does "artisic iron" someone who'll look at it as sculpture/art
good luck... keep us posted... pretty sure i'll build one like that when i get the chance.... i know that big round pipe/tube i have now has a place in the future...
p
Actually, I plan on using this same design on the next house I'm gonna build. So's I really gonna build two. Work out the bugs on this one, first.