I like the look of a concrete and want to make a raised (3′ to 4′) multilevel concrete patio. I was thinking of concrete piers with a steel reinforced pad on top. How do I determine how many piers I need. How thick should the pad be. how do I form it. I would like to find a good book on the subject but don’t know what to look for. Who would be able to put together a design a structural engineer? I’m a bit of a Newbie at this type of job but would like to do it myself if possible.
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Go to your local library...they should have some books on concrete work.
As for a raised patio...you never indicated what the overall dimensions would be, or how thick you wanted to make the pad.
You did mention raising the patio off the ground approx 3-4 feet. Instead of piers, you could build a wall perimeter (with footer) out of concrete or concrete block. Make the wall the same height as your desired finished patio height, minus 4 inches. Dump gravel infill and compact this bed. Now form and pour a 4 inch slab on top of this gravel bed. This is one method...if you want to avoid using piers...there are other techniques as well.
Davo
I like the idea of a perimeter foundation filled in with gravel for the slab. This is by far the cheapest method and eliminates the need for any sophisticated engineering. It also has the added benefit of eliminating a barely accessible storage space that will quickly fill up with junk that should be thrown out or given away.
Years ago we built a suspended slab for a screen porch as part of an addition project. We consulted with an engineer who specified the steel mat and an integral concrete and steel beam to span the center of the slab. The steel work was simple and not that expensive. The form work took a lot of time and about 150 short studs in the basement to support it. The finished product was beautiful but the space underneath was low and expensive.
You might find some relevant info to your questions at this website:
http://www.concretehomes.com/
Davo
Thanks for the lead. I don't know the dimensions yet or the pad thickness. I only have a general idea of what I want to accomplish. I wanted to see if it’s possible for a reasonable amount of money and the possible construction techniques before I start a design. I was hoping not to have to fill in underneath as this area could be a great place to use for outside storage. Blocks would work but I assumed that concrete piers my keep the cost and complexity down as well as better access to any storage area underneath. Is there a professional that can do a design for me? Would that be an architect or an engineer?
As mentioned, a lot depends on size. A lot depends on on soil condition.
Keeping the cost down on a project like this is not an option.
Setting a concrete slab on piers is not simple. The piers themself must be set on footing that are large enough, thick enough, and have the correct amount of steel in them to distribute the weight of the slab over a footprint that your soil conditions will support. There must be enough steel in the piers to resist horizontal and lateral stress loads. Vertical steel is tied to the steel mat in the footing and stubed up durring the footing pour. The horizontal steel in the piers must be bent and tied to the vertical. The vertical steel in the piers should also stub up and turn out into the slab. None of this steel can be formed or cut with a torch. If you have a rebar cutter/bender you are going to have a lot of fun. If not, you pay to have all of the rebar cold formed and cut by a fabricator.The slab must also have the correct size and spaced rebar, at the correct height in the slab.
None of the above is a simple to figure out, easy to do, or low in cost.
Since you are just kicking this idea around, why don't you run it by your local building code enforcement and permitting authority? They will tell you what is required in the way of permits, engineering approval etc. for your area.
Good luck,
Dave
Just a thought, but you might consider using spancrete (I think this is the name). The product that they use for commercial floors and parking garages and stuff. You might be able to use this as a substrate then form and pour your curves and levels above it. Don't know if it would work, just an idea. Jon Blakemore
Two odd thoughts:
Maybe rejected precast parking garage slabs. The T's would probably be a little deep for his purpose, and the crane might make a few ruts in the flower bed, but...
Back when I was in high-rise construction, we used a metal deck supported by structural steel, and poured a 4" thk slab. The deck was very similar to (but NOT the same as) square rib metl roof panels. Depending on the spans involved, this might work.
To answer one of his original questions, he could approach either an architect or structural engineer for advice. Probably the architect, because I suspect the engineer would only want to provide a specific design for an already thought out layout, but the engineer would ceretainly have the knowledge.
Do it right, or do it twice.
Yuo might try your local hiway department . They have specs. for box culverts /concrete bridges . Basic design of what you might want ,you can change the hights of the walls ,but not the length of the spans unless you want to shorten them.
You might have something there. Skip the highway dept, just go to a precast company and buy a couple of box culvert sections. Excavate a little, do a proper foundation for the weight involved, set them in place, a little topping slab or floating wood deck, great place for the grandkids to play.
Do it right, or do it twice.