retaining-wall
Wondering if I can have people's thoughts on this retaining wall I'm building. It's a mortared CMU wall with rebar 24" o.c. It's on a slope and it will have a concrete slab and a fence right above the backfill. Above we'll have a combination of foot traffic, outdoor dinning area, outdoor sitting area (with outdoor sectional), etc. Taking that into account, from the drawing does this look like it's a sound and strong enough wall to hold the conditions above? Thanks!!
Are you talking about a retaining wall above the house's ground level, or below?
If above, you will need to provide enough clearance for any emergency exits but other than that I can't think of any limit. As for being built into the house, you could think of a walk-out basement as having a retaining wall on the uphill (non-walkout) side.
If you are talking about a wall below the house, you need to make sure you don't undermine the house's foundation. The distance you need to be away depends partly on the soil so if you are wanting to get close to the house (say, closer than 2 or 3 times the wall height) you would definitely want to talk to an engineer.
This is about load bearing and claims. The pressure associated with 2 ft of dirt is probably well within the load bearing specification of the blocks in question. 3 feet may not cause any issue, but you cannot hold the manufacturer liable if it collapses and/or if someone gets hurt.
If you exceed the manufacturers specifications an inspector might have a problem with it too. I would recommend adding weep holes, french drains, and possibly a deadman. And since much of the weight comes from moisture, the backfill could be gravel, to improve drainage. In fact there are lots of ways to shore-up a retaining wall, but the onus would be on the "engineer" if something were to fail.
Here's a good picture of some retaining wall features. Source: http://www.fairfaxcounty.gov/nvswcd/youyourland/soil.htm
Edit- A tie back is used on block walls. Screw types and anchor plates are common, but there are probably many ways to accomplish the act of tying or holding the wall in a similar fashion.
Best Answer
There are too many unknowns to answer this question. What type of soil is there so a reasonable active pressure, passive pressure, and sliding resistance can be determined? What surcharge is on the 7" slab? How far from the face of slope is the wall located? What is the frost depth? What type of masonry? Grout? Mortar? Reinforcing?
This wall is high enough that a building permit and engineering is required. Do not attempt to design it yourself. Without all the answers to the above questions, I already know whoever drew the detail is not qualified. The vertical reinforcing is too far apart, and it all should be located on the tension face (soil side) of the wall. There is also a need for horizontal reinforcing in the wall, and vertical and horizontal reinforcing in the footing key. Sorry, but spend the extra bucks to get it designed right.