Raising the ground in a large area that will eventually be a patio. What type of substrate to use?

Question

I'm gearing up for a bunch of landscaping at my new home. The backyard is kind of a mess: rotted-out deck, terrible lawn, low spots, high spots, etc. It's mostly all going to get redone.

This question pertains to the current deck area. The deck is getting ripped-out as it's not salvageable. The area is ~24' x ~25' so it's almost a square. It sits in between the house and a garage in the back, so there is the foundation of the garage and house on two ends of it. The ground level below the deck is about 1' below the grade of the house and garage. My plan is to build up the grade in this area so that the ground is more level with the house and garage doors. I then plan to build a roofed pergola to cover it and make this into a patio area with a wood-fired oven in the middle. The ground under the pergola will be a majority of gravel, with pavers placed in the most-used areas.

To build this plot up ~1 foot higher, I think I need around 21 cu. yds. of substrate but I'm not sure what the best type of substrate to use is. The current ground is relatively hard-packed soil. I haven't dug down too much but judging from my neighborhood, there should be a bit of clay and kind of gravelly, dark, rich soil. It's quite compacted so I'm not worried about it settling too much. What would be the most cost-effective way to fill in this area? I believe I'll have to build small retaining walls on the two ends of the square that are not backed by the house and garage. I will also be sure to make small "egress" areas so that my crawlspace vents do not get covered up.

Answer 1

I think the most effective way would be to not fill it at all. How about a raised deck on concrete sono tubes if you are in a freeze are or deck feet in warmer climates?

If you change the grade you must ensure that any water runoff including downspout (gutter) water has someplace to go away from your house.

Raising the grade is a lot of work. To fill the area you could use stone dust compacted in layers. As a loose material you would have to have a retaining wall to prevent it shifting. This requires over 20 cubic yards ( 24' x 25' x 1' = 600 Cft or over 20 cubic yards). If you allowed for setting and compaction 25 cubic yards of material is not out of the question. At this amount you need a bobcat or front end loader and a compacter and a retaining wall that will need a base. It just starts to look like a lot of work.

Answer 2

I agree, a deck will not help the value of your home. A patio would. Even better is to make the patio the same level as the floor in your home.

We used ground up concrete compacted, then 5/8 minus compacted 4" and then builder's sand 2" as the paver base. No concrete, no space between pavers. These are called CMU walls, planters (concrete modular units) with concrete caps. This increased the value of their home by...an awful lot! They wanted a deck at first and I talked them out of a deck, this is a little more expensive but not much. This did increase the value more than a second bathroom or a remodeled kitchen! That white fence in the background stopped the cat box feeling and pulled everything together. They walk right out of their door onto the patio... and all vents were sectioned off and covered with nice louvers.

When framing the patio we used 2X12 pt lumber and at the same time framed off the vents and utilities. Keep framing away from the siding (you should be able to see in the second picture to the left). The cmu walls are PISA II with an ashlar pattern. I would recommend LOUDLY to stay with dove gray mixed with a bit of darker gray. Lighter gray concrete caps. Goes with everything and is a natural color in any landscape. The colors actually look like the concrete is dirty, or moldy, seriously. This is not the time to play with color. Everyone who did were sorry later. Oh, the pavers are the classic roman cobble 7X9X2, no space left between cobbles. There are black plastic edgers to ensure no movement and are fairly invisible which is what you want. When choosing which direction the longer side should be laid, always look from the main view. In this case from inside the home and from the entrance to their path...the long side should be PERPENDICULAR to those views otherwise that long side becomes very visual and distracting. Your professional artistic friends and contractors will especially be bothered...grins! The wall height on the inside from patio to top of cap should be between 15 and 18". These cmu are ONE SIDED which dictated the design and depth of wall. Thick walls are more 'stable' looking as well. But today there might be cmu that are two sided. This would help with fire pits...truly one of the best things you could add to your patio. ALL the neighbors had to have patios like this...good for our company.