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platinum
09-01-2011, 04:32 AM
I have an existing stamped concrete slab that I would like to put some pillars on the corners. I have 2 questions.


Should I be concerned with the weight on the ends of the slab?
How do you adjust for the grade of the concrete for run off. Its slight but it would be noticeable. I was going to put some mortar at the bottom for the course layer to level it out. Is that sufficient?

DVS Hardscaper
09-01-2011, 08:26 AM
1) No
2) Yes
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Crusher Run
09-02-2011, 06:29 PM
Use grout NOT Mortar. Big difference.

What does the stamped slab have for reinforcement?

STL Ponds and Waterfalls
09-02-2011, 06:52 PM
Use grout NOT Mortar. Big difference.

What does the stamped slab have for reinforcement?

Mortar will be fine and grout will get a little pricy if you need to use a lot. Did you mean thinset or grout?

Crusher Run
09-02-2011, 09:40 PM
Cementious grout. We get 50lb bags for about 19 dollars, and it's a 10,000 psi mix!! It's Harris Construction Grout. Non shrink non metallic, it's real good stuff. We use it for our leveling plates, which support the steel in large commercial buildings.

Mortar is more about bond strength, flexibility, durability, with the strongest type (M type) being 2,500 psi.

If you just need compressive strength, then grout is a better choice.

STL Ponds and Waterfalls
09-02-2011, 09:45 PM
Really, that's pretty interesting to know. 10K psi strength is good. :)

Crusher Run
09-02-2011, 10:14 PM
Really, that's pretty interesting to know. 10K psi strength is good. :)

Yah, just in case his pillar weighs like 75,000 lbs lol

platinum
09-03-2011, 08:46 AM
Use grout NOT Mortar. Big difference.

What does the stamped slab have for reinforcement?

A little more info on the slab. it's about 400 sq/ft, 4 inches think, has a rebar grid for reinforcement and sits on about 10,000 lbs of limestone, no joke. Yard is sloped pretty bad so we build it up allot.

It's about 3-4 years old now and I'm starting to see some settling on the front section of the slab. This happens to be where the pillars would be going as well. It sounds like the extra weight is not a problem but could it make that section settle faster? The Pillars will be around 3 foot tall.

appreciate all the feedback

zedosix
09-03-2011, 10:05 AM
What about cutting out the small section where the pillar would end up. This way you dont need to worry about the slope or settling.

STL Ponds and Waterfalls
09-03-2011, 10:56 AM
I don't remember what you said the pillars will be made of, but that can play a part. Full veneer will be a lot heavier than a cultured stone etc.

Plus, what Zedo mentioned is a good idea!

Crusher Run
09-03-2011, 11:17 PM
I wouldn't cut out anything. If there is a reinforcement steel grid in the slab, you would be taking out part of the grid and the concrete's shear strength would ultimately be weaker. If the slab is showing signs of settlement, it's going to do what its going to do whether you put a pillar on it or not.

zedosix
09-04-2011, 10:57 AM
Assuming you put a pillar on there, and it does move, now what? You'll have to remove the pillar and concrete, good waste of time unless you've nothing better to do. Cut the concrete and install a pillar. Worst case scenario, you remove the concrete and leave the pillar thereby not wasting your time and material. To further enhance it you could cut beyond by a foot or so and install a nice decorative 12" x 12" paver. Thats how I would go about it. Good luck with whatever you decide. Just remember one thing, when you install pillars they should typically be on there own base, not on a huge slab, especially one that is showing signs of wear.

platinum
09-04-2011, 08:35 PM
Thought I would attach a pic so you could see what I was talking about. I think I have a couple of options.

1. build on top of the exisisting slap.
2. cut where the pillar would go and create a new base for the pillar
3. build the pillar on the outside of the exsisting slab
4. maybe do something else with the space all together?

Crusher Run
09-04-2011, 10:30 PM
Nice looking space. I wouldn't do anything lol. Are you planning to put the post on top of the pillars. Going back to my original statement, If you do cut out the corners then that won't weaken the slab.
But I don't think that if you do build on top of the slab, it's going to settle faster.
The ground may be heaving from freeze thaw cycles. It may have nothing to do with compaction.

platinum
09-05-2011, 08:33 AM
If the pillars were there before I built the pergola I would have put them on top. I would be a ton of work to do that now.

Thanks for the comments on the space. The thought was to build pillars up this year, then next year build a access area to the yard out of the center of the slab. That would go where the hostas and evergreens are today.

DVS Hardscaper
09-05-2011, 11:10 AM
Nice pergola.

The patio is too small for pillars, easy as that.

Keep it simple.

Know when to draw the line.

It's like when people buy all these accessories for their little pick up truck. After a certain point it looks crappy.

Sure the client may *WANT* pillars, but it's not a wise move architecturally. It's already cluttered and confined.

Forget the pillars and try to sell them an Aquabella water feature.


And good lord, I hope the home owners designed and installed the planting arrangement!


,

platinum
09-05-2011, 02:55 PM
its my place so no client to deal with... its ruff growing anything there with all the limestone under it. alot of creamping ground cover starting to take though so hopefully it will look better next season.

thanks for the feedback.

Bru75
09-05-2011, 04:29 PM
You could just surround the lower few feet of the posts with block or stone, maybe that way you could stay off the slab completely.
I agree that freestanding columns might make that area seem a little too crowded.

DVS Hardscaper
09-05-2011, 06:24 PM
Oh yeah if its where
You live there forget the pillars. It'll be too cluttered.

AND GET THAT BLASTED GRILL AWAY FROM THE HOUSE before it catches the house on-far!!
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Crusher Run
09-05-2011, 09:53 PM
That pergola is sweet. What type of wood is it?

platinum
09-06-2011, 09:08 PM
Thanks for the feedback guys. When you say surround the lower few feet with stone, do you mean like a veneer to put on the post or just build some pillar type around the post.

The pergola is just pressure treated pine that was stained to match the cedar fence.

Bru75
09-07-2011, 12:38 AM
Thanks for the feedback guys. When you say surround the lower few feet with stone, do you mean like a veneer to put on the post or just build some pillar type around the post?

Depends on what you use. You could use retaining wall block by digging down a foot or so and compacting a gravel base around the post. Build the column as you normally would, surrounding the post and finish it with caps.
If you use real stone, I would dig deeper, depending on the frost depth in your area, pour a concrete footing and build up from there with cinder block to just below grade and stone from the ground up. I'd suggest leaving a gap of about an inch between the stone and wood with weep holes at the bottom. This will allow for movement in the wood.
I wouldn't veneer directly to the post.
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