Building a Backyard Patio

[Chris7687]

Hey guys,
It's been a long journey, but it looks like my fiance and I are about to close on our first home. We have spent the last 6 months waiting out a pain in the arse battle between the trust over the property. Luckily, we have been living in the house during this time, so we have been coming up with ideas of what needs to be done and in their order. The first two are building a patio and having the master bathroom remodeled!

Currently, when you walk out the back door of the sun room there are concrete pavers and a small flower bed. Having 3 big dogs, this is a nightmare, as they love to track in all the dirt/mud that is between the pavers and the mulch where the flower beds are. What I envision is a solid slab that runs from the existing pool deck to the side of the sun room. Also, a pathway that runs the backside of the sunroom.

I have never poured concrete, but I am trying to recruit a few friends that have and have the tools. My plan was to remove and level everything, frame and square it all out, then drill and place rebar into the existing foundation as to keep the slab from sagging, but I am not sure the next step. Should I be placing gravel down and then wire mesh and pouring the concrete over that? Or should I just be doing the wire mesh, which will go on top of the rebar I have placed into the existing house foundation? There will be a lot of weight on this slab as I plan on building a 12+ person picnic bench and putting an awning over the slab at some point, so I will need to put a good footer at the lip of the slab. How deep should I dig the footer and how apart should I be putting supports?

Also, the slope of the slab, do I incorporate this into the frame height or is this all from smoothing it out? Another thing, where and how do I put in the joints? How wide apart for such a big slab?

Lastly, I plan on putting an awning over the slab at some point so I will need to put a good footer at the lip of the slab. How deep should I dig the footer and how apart should I be putting supports?

Any other advice you have please share it! I am trying to save myself money by doing this myself, but don't want to sacrifice quality!

Here are some pictures below to help visualize the build.

Arial shot of home


Rough Sketch


- The orange represents the proposed concrete.

Shots of the backyard

Walking out of the sunroom


Looking left out of the sunroom


Looking back at the door to the sunroom


Looking back where the walkway behind the sun room will lead to

 

[Chris7687]

Also, will concrete trucks have chutes long enough to reach my back yard from say the drive way?

 

[Newsman]

Also, will concrete trucks have chutes long enough to reach my back yard from say the drive way?

I'm just guessing here, but probably not. You may need a concrete pumper truck to pump it over the top of the house and where you're wanting the new slab. I can't speak for anything else, but if you know where you want your supports for the awning, you might go ahead and dig those holes and put tubes down them for the supports.
Now, it doesn't look like you have to worry much about heavy freezing/thawing cycles where you are, so I wouldn't think you'd need to have more than a 6 inch slab, but check with an expert.

 

[Hello]

That is a lot of questions and definitely some things that you need to think about here.

I'm unfamiliar with code in your area but in terms of a slab foundation, I would not leave anything to chance with the footers. First, you really need to know what soil you're working with. Here, we have clay. The load bearing value of our soil is approximately 2000 pounds per square foot. This value helps determine the size of the footers. I thought footers had to be no less than 12" below undisturbed soil. That is, you dig until you get to soil that hasn't been tilled or turned or anything of the sort. I can't say how far down that really is for you but the column supports you can buy at Home Depot for about $12 a piece will be long enough.

You can extend your footer load by using the upside down T footer. I cannot recall the name. That will allow you to put more weight on the slab. This is a porch, basically, so I doubt you need to go there. I do think you need minimum 12" below undisturbed soil. I think footers are 15" wide.

Laying the concrete should be done over the rebar, gravel and mesh, I think. Again, I am not an expert and I've never actually laid concrete. This just comes from past education. Off hand, I think the frame needs to support the slope. I think your life would be easier. If you intend to shape concrete in such a way that it slopes, I assume it could come out very uneven. Perhaps a skilled professional can pull it off, but I'd frame it. My intent was to frame it to make a pathway and not worry about having to smooth it into a slope. Concrete starts to set fast so if you're futzing around with it then you could find yourself in a heap of trouble. Also, the integrity of the concrete could be diminished if you don't work fast. I think that is about right.

The truck cannot reach to the backyard. Like the guy said above, you need a pusher or a bunch of wheel barrows and buddies. The pusher will get the concrete to you faster, which is necessary. Again, it hits that open air and the clock really starts as far as I know.

You may want to look into machine rental to do the demo. That's a lot of work. It is all fun and games the first hour but after that, it is a total **** show. I pulled up a simple thin slab that was only about 2'x2'. Hours later I was inside drinking and wondering what the hell was wrong with me! If you have a larger job, rent a machine for sure.

Pardon the length of my reply. My best advice is to definitely be careful and if you're doubtful of anything, hire someone. The one red flag I see is drilling into existing foundation. Unless I misread, I would certainly check into whether or not that can be done. Messing with the slab under an existing structure sounds like it could go bad. Not to be a total debbie downer. Take this all with a grain of salt though. I'm a desk jockey, not a construction worker, engineer, or architect.

 

[Chris7687]

Hmmm.. It sounds like some things are better left to the professionals. I am going to try to get a few more quotes. I just am hard pressed to part with $3,300 for concrete work when I'm already paying $10k for a bathroom!

 

[Newsman]

Hmmm.. It sounds like some things are better left to the professionals. I am going to try to get a few more quotes. I just am hard pressed to part with $3,300 for concrete work when I'm already paying $10k for a bathroom!

Yeah. You MIGHT be able to do it yourself, but best to leave stuff like that to the pros. Maybe you can reduce costs by clearing the existing stuff yourself and then letting the pros take over from there?

 

[Natdavis777]

First, dont over think this project...

As with the getting the mud to the patio site. A pump truck around here will cost at least 1k$ just to get the truck there. That is not with the cost of the concrete. Lowes and other local supply stores have motorized buggys that will carry around 1/3 cubic yard ( i believe) so that would be your best bet at getting the concrete from the street to your site. If you have enough people, you can wheel barrow it around, Ive done this in the past. depending on how many yards you are pouring, it could take awhile though.

As for tying in rebar to the existing slab to prevent the new slab from sagging...not worth it. you are going to saw cut the new slab as it is, so the rebar wont prevent the whole slab from sagging. A good subgrade will prevent this. You only need a 4" slab for a patio, its not going to be load bearing, so get a good foundation and tamp and you shouldnt have a worry about sagging.

As for slope, a 2" downgrade over the course of the whole patio in one direction will suffice. This will sweep water off. From the looks of your location, you dont have to worry about freezing.

Again, its not load bearing, dont worry about throwing wire mesh in. You dont plan on parking a truck on it, so just go with fiber mesh in the mud for security. You will pay a few extra bucks per yard, but will fair the same as throwing down some wire.

As long as you have someone who can do a decent job at finishing, you shouldnt have many issues.

I did commercial construction for 6.5 years and have poured and finished my fair share of slabs, footers, sidewalks, mezzanines, etc, and patios as side jobs.