OT: Steel deck - seeking advice/idea

[Rex]

My deck situation

When we moved into the house in 2001, it had a big deck on the slope behind and beside the house. All wood, 32-ft by 20-ft. It was getting pretty ragged, so I restained it, and built all new rails and posts last summer. It looked great!


Last Jan 17 (my birthday) I walked out the back door into a wall of flame. The deck was on fire and almost totally engulfed. That fiberglass hot tub might as well have been gasoline! Luckily it did not catch the house, but it was close.



So now I have a big black area where the deck was. I intend to rebuild it, probably bigger.

Toward that end, I found through a friend 150 pieces of 2.5" square tubing, 10-ft long with 7/16 holes every 1.5 inches, all 4 sides. I intend to build a framework with that, like a manly erector set. Not sure what I will deck it with. Probably not wood.

Right now I'm at the point of digging post holes. Trouble is the hillside is very rocky. I bought a $150 jackhammer which is working pretty well. but it's going to take me a couple weeks to dig all the holes unless I come up with a better method.

So that's where I'm at. My rough plan to follow

[Rex]

So, I now have a mostly bare site, with a slope. And rocks. Lots of rocks!
Here is what it looks like now.


I also have steel posts: 120- 2.5" X 10-ft, plus a few 2" and 1-3/4". All have 7/16 holes about 1.5" apart on all sides. Yes, highway sign posts, 2nds.


Here is the plan view of the design. The long (40-ft) edge is at the bottom of the slope.

I need to lay out my post holes on this site, then dig the holes, then accurately place and align the posts so they bolt together plumb and level.

My original plan is to use the existing deck as shown to set the first few posts. Then work out from there, being sure each new post has at least one hole that aligns with corresponding holes in two of the existing posts. In the process, I would remove the old deck when it was no longer useful. Horizontal beams would be bolted up to the first few poles and used to align the remaining verticals, working away from the start point.
Excess length would be cut off with a portaband saw after the poles are placed.

[Rex]

So here are the challenges I see:

1 - Digging the post holes. The ground is very rocky. Some places the ideal location is right in the middle of a big boulder that cannot be moved. My $150 jackhammer doesn't cut it. Other places I am able to dig with the jackhammer and pull out rocks the size of my fist, all the way down. One hole took two hours. Yesterday I learned a neighbor has a PTO-driven auger for his small tractor, so we may try that. Not sure if it will handle the rocks.

2 - Alignment, as described above. Would something like this be worth having? (It's all about the tools, right?). It's about $165, refurbed. Anything out there that is a better value?



I have never tackled anything this big.
Looking for insight and suggestions from the experienced builders among you.
I don't want to end up with Rex's Folly

[BobinOK]

Post hole digger on a tractor won't touch the rocks unless they are small enough for the auger to dig up. If the rock is big and stable enough, drill and use anchors.

A rotating laser level with a sensor (receiver) is what you really need to level the deck posts. You will not be able to see a laser light in the day light. Was lucky when I built my car port, friend had one from work he loaned me. Might be able to rent one, they are expensive to buy.

[Rex]

Post hole digger on a tractor won't touch the rocks unless they are small enough for the auger to dig up. If the rock is big and stable enough, drill and use anchors.

I figured the jackhammer would be required for some. What do you drill it with? What sort of anchors? These are sandstone, but some of it is pretty hard.

A rotating laser level with a sensor (receiver) is what you really need to level the deck posts. You will not be able to see a laser light in the day light. Was lucky when I built my car port, friend had one from work he loaned me. Might be able to rent one, they are expensive to buy.

Harbor Freight has one for $60. Has anyone tried it?

I'm not in a rush on this, so it might be better to buy something. Or find someone who owns one locally. I'll drop by Home Depot and see if they rent them.
Thanks for the input.

I think once I have the first 3 or 4 up and plumb, the rest will be easier. One hole at a time. My goal is to have it finished by July 4.

[Machine]

I've built a few post-hole foundations for a coupla sheds I have. I dug the holes using a rented one man post hole digger and then placed these things called sonotubes in the holes...



Once I dropped the sonotube in the hole, I had to center them best I could, which wasn't always easy to get precisely correct. I used a string grid and level system for my entire layout with no fancy laser stuff. Maybe the laser would have made it easier, not sure. But I would dig the hole as carefully as I could, oversized to allow some adjustment of the tube after it was in the hole. Then poured dirt around the tube and packed it into place in graduated layers using a 1x3 wooden plank...constantly checking the alignment and adjusting the sonotube along the way.

After all the tubes were in place, I'd mix the concrete and pour into the tubes, again checking level with the string method. I inserted a single rebar length into each tube to help ensure lateral strength. I also inserted metal tie straps that could be nailed to the 4x4s that set upon the piers after the concrete was cured. You want something to nail into and secure the shed (or deck) to prevent it from lifting up in hurricane winds (which is code in my parts).

But since your soils are all rocky, plus you're in Texas, I suspect you don't have to worry about the soil freezing and heaving up and down every winter. So maybe you don't need sonotubes and post hole foundations? Although I know parts of Texas get serious storms, winds and maybe tornadoes from time to time. So connecting to the surface rock in some way using a hammer drill and straps might be a good idea. Otherwise I would think you could get by with concrete pads sitting upon the rocky surface. I'd check your local codes, if applicable, and take guidance from that. Dont be the guy that builds an elaborate deck just to find out the local govt wants to tear it down because you didn't get a permit or inspection. Seen that where I live, YMMV.

[Lee Cordochorea]

Would something like this be worth having? (It's all about the tools, right?). It's about $165, refurbed. Anything out there that is a better value?

A couple decades back we had the task of building out network support infrastructure (various types of tray on steel supports) spec'd to 1/64" end-to-end (about 120'). We discovered we could get closer with a 4' level than we could with the laser. Of course, your points will be much closer together, so you won't have to deal with a nasty fat red line. You probably didn't spec silly tolerances either.

I did used a similar laser to lay out a greenhouse foundation a couple years back. Worked fine.

I suggest something with a versatile mount, though. Those "legs" look like they would just get in the way.

[Rex]

A couple decades back we had the task of building out network support infrastructure (various types of tray on steel supports) spec'd to 1/64" end-to-end (about 120'). We discovered we could get closer with a 4' level than we could with the laser. Of course, your points will be much closer together, so you won't have to deal with a nasty fat red line. You probably didn't spec silly tolerances either.

I did used a similar laser to lay out a greenhouse foundation a couple years back. Worked fine.

I suggest something with a versatile mount, though. Those "legs" look like they would just get in the way.

I know I'm probably overthinking it. I took a 4' level out there today and the existing deck is close. I expect I will dig the first 4 holes, lay two beams along the corner, bolt two or three posts vertically hanging in the holes, tighten everything up in alignment, then pour concrete. Then move out from there with a horizontal beam leveled to the next post etc. I'm just worried about tolerance stacking. I don't mind it being 1/2" out of level over the 40-ft length, I just want it straight.

[Rex]

I've built a few post-hole foundations for a coupla sheds I have. I dug the holes using a rented one man post hole digger and then placed these things called sonotubes in the holes...

That's a pretty interesting method. My deck is about 5 feet off the ground at the edge. Might be a bit tall for that.

But since your soils are all rocky, plus you're in Texas, I suspect you don't have to worry about the soil freezing and heaving up and down every winter. So maybe you don't need sonotubes and post hole foundations? Although I know parts of Texas get serious storms, winds and maybe tornadoes from time to time. So connecting to the surface rock in some way using a hammer drill and straps might be a good idea. Otherwise I would think you could get by with concrete pads sitting upon the rocky surface. I'd check your local codes, if applicable, and take guidance from that. Dont be the guy that builds an elaborate deck just to find out the local govt wants to tear it down because you didn't get a permit or inspection. Seen that where I live, YMMV.

It's basically a rock hill. You should see the boulders that came out of the driveway yesterday. That one posthole I managed to dig produced enough fist-sized rocks to fill the hole back up. And no frost heaves. Even though it's sloped, soil stability is NOT an issue.

I'm in the county, so no codes, no permits. It's more "Hold my beer while I figger this out".

[Sparky_NY]

A string will get things straight and in line. A water level will work over 40ft easy and dirt cheap. For vertical, a plumb bob works well. For distance measuring, Bosch has laser measurement tools that will do 50ft with 1/8 inch accuracy and cost about $50 Lasers work, contractors use them constantly but they use a expensive version. All the above methods were used a couple years ago when I built a 32x50x10 pole barn building as my new toy box, the methods worked great.

[BobinOK]

Something in this may help or give you ideas...

My carport is supported by 6 6x6x12 foot square steel poles. I dug the holes with a post hole digger on my tractor, measured and marked a point on the 6 poles that would be about 5 feet up when they were at the right height in the holes. Set the laser level up on the tripod in the center. The laser receiver has an point on it that indicates where the laser is when it is at the right height plus lights that tell you which direction you need to go. I adjusted the height of the poles in the holes with my marks all lined up by the laser. Poured in cement, checked plumb and rechecked the height with the laser. I put in a 2 inch drop in 24 feet just to let the rain run off and it came out perfect.

A string level might work OK but the laser was dead on with no guess work. A hammer drill is the way to drill rock, not that expensive for a home owner version. Might check Harbor Freight for one that will be cheap but good enough to drill what holes you will need. Mine is a Milwaukee and even it wasn't that expensive.

[Rex]

A string will get things straight and in line. A water level will work over 40ft easy and dirt cheap. For vertical, a plumb bob works well. For distance measuring, Bosch has laser measurement tools that will do 50ft with 1/8 inch accuracy and cost about $50 Lasers work, contractors use them constantly but they use a expensive version. All the above methods were used a couple years ago when I built a 32x50x10 pole barn building as my new toy box, the methods worked great.

Definitely considering a bubble level. All the string I have is stretchy, especially over the 40 feet I'm dealing with.
The advantage of the laser would be seeing alignment across the several planes at the same time.

If I were working on level ground this would be much easier. Dealing with the slope makes error compounding more likely.

[Rex]

My carport is supported by 6 6x6x12 foot square steel poles. I dug the holes with a post hole digger on my tractor, measured and marked a point on the 6 poles that would be about 5 feet up when they were at the right height in the holes. Set the laser level up on the tripod in the center. The laser receiver has an point on it that indicates where the laser is when it is at the right height plus lights that tell you which direction you need to go. I adjusted the height of the poles in the holes with my marks all lined up by the laser. Poured in cement, checked plumb and rechecked the height with the laser. I put in a 2 inch drop in 24 feet just to let the rain run off and it came out perfect.

A string level might work OK but the laser was dead on with no guess work.

What kind of laser did you use? A rotating beam?

A hammer drill is the way to drill rock, not that expensive for a home owner version. Might check Harbor Freight for one that will be cheap but good enough to drill what holes you will need. Mine is a Milwaukee and even it wasn't that expensive.

I actually have a new Dewalt 20V hammer drill. Not sure what I would use that for - anchors?

Some of the post locations are right on top of boulders with the surface at or near ground level. For those few, would it be OK to just have them resting on the rock? Maybe pouring a short column with a simple form? There would be other posts nearby with a proper hole and concrete.

[Willy]

Those steel posts are called Telespar. I've pounded a lot of them in the ground while working for a highways maintenance contractor. We used a spud in the end made from a piece of solid steel. It allowed you to drive the posts into some pretty unforgiving ground using a 6-8 lb. sledge without deforming the post.



However whenever we got into several areas of our territory where we knew the ground was extremely boney we would not even think of using the standard sledge as this was almost guaranteed to be an exercise in futility. If one was fortunate enough to get a post in far enough the post was probably as buggered up as the guy swinging the sledge.
However we did have access to one truck in the fleet that was equipped with a hydraulic telespar driver. It resembled a large construction grade air jackhammer, although this one was as mentioned hydraulically driven. It was magic using this tool. In exactly the same spot where one was left sweating and driven to tears with a bent piece of telespar, that unit would pop a telespar anchor into the ground straight and unscathed.

I should clarify the above statement by saying that the long telespar posts are not driven into the ground by themselves.
A 3-4 ft. anchor, which is just telespar one size larger, is driven in first then the main section of telespar is dropped into it, much like a trailer hitch slides into a receiver, and then pinned into place using drive rivets like these.


Makes assembly very fast and all you need is a hammer to secure them and a punch to drive out the "bullet" if one needed to disassemble anything assembled using them.

Hope the info helps, see if you can rent one of the drivers if you go this route. Digging holes in rocky ground is no fun.
Good luck on your new fireproof deck!

[Willy]

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,A hammer drill is the way to drill rock, not that expensive for a home owner version. Might check Harbor Freight for one that will be cheap but good enough to drill what holes you will need. Mine is a Milwaukee and even it wasn't that expensive.

Bob I trust you must mean a rotary hammer and not a hammer drill. Big difference in performance when drilling rock, although most folks use the term interchangeably between the two.