Retaining Wall
Retaining Wall
(OP)
Hi
I am planning to build a retaining concrete block wall 8 feet high. The wall length is 8 feet at the highest level then turns into 4 Feet. I have sandy soil and my location is on a slopped hill. The house is 100 years old and the retaining wall that was there is in pretty good condition. My landscaper believes that I will be okay by drilling Sono Tubes and then putting a concrete footing on top then rebar and concrete block going up to the desired heights. He also said that he will put in proper compaction and drainage every 4 feet to go out of the wall. Question is this: 1. Is he right, 2., how big should the footing be? (I read somewhere that for 8 feet high block wall you need at least a 4 foot footing). 4. Do I need to put some type of tie back into the existing soil? 5. can I use a geogrid of some sort?
thanks
Ivan
I am planning to build a retaining concrete block wall 8 feet high. The wall length is 8 feet at the highest level then turns into 4 Feet. I have sandy soil and my location is on a slopped hill. The house is 100 years old and the retaining wall that was there is in pretty good condition. My landscaper believes that I will be okay by drilling Sono Tubes and then putting a concrete footing on top then rebar and concrete block going up to the desired heights. He also said that he will put in proper compaction and drainage every 4 feet to go out of the wall. Question is this: 1. Is he right, 2., how big should the footing be? (I read somewhere that for 8 feet high block wall you need at least a 4 foot footing). 4. Do I need to put some type of tie back into the existing soil? 5. can I use a geogrid of some sort?
thanks
Ivan






RE: Retaining Wall
By code, any wall over 4 feet requires a structural engineer at least to analyze and design it.
Hire a Structural Engineer and fire the landscaper.
Mike McCann
MMC Engineering
RE: Retaining Wall
Eight foot tall retaining walls are not to be trifled with.
RE: Retaining Wall
Question is this:
1. Is he right, have him show you the calcs...
2., how big should the footing be? (I read somewhere that for 8 feet high block wall you need at least a 4 foot footing). possibly wider, but do you want to base this on "something you read somewhere"?
4. Do I need to put some type of tie back into the existing soil? probably not the best idea
5. can I use a geogrid of some sort? usually only used for fill construction
RE: Retaining Wall
Cody
RE: Retaining Wall
The design of a stable wall is not a trivial exercise, both because of soil considerations and the wall itself. Improperly designed or built it will rotate or slide (soil failure) or the wall itself can deform or completely fail.
RE: Retaining Wall
Will the footing be subjected to frost on the low side? If so, heaving may be expected and the wall should not be tied in to the house foundation.
BA
RE: Retaining Wall
EIT
www.HowToEngineer.com
RE: Retaining Wall
The height of only 8' is not a problem. Within 3 miles of me, I have numerous segmental walls (no footings obviously) that are 12' to 20' high that form inside and outside curves to retain the soil form around buildings placed above and behind the SRW walls.
Normally, the height of a wall to be engineered ranges between 3' and 6' depending on the location for permitting.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Retaining Wall
RE: Retaining Wall
A reinforced block retaining wall need not "look terrible after a few seasons". If the earth side of the wall is tanked (waterproofed), then you can use an acrylic coating on the visible side, and with maintenance every few years, the appearance is quite acceptable to most people.
RE: Retaining Wall
RE: Retaining Wall
RE: Retaining Wall
If you are talking about this 8' high retaining wall, the vertical reinforcement would be at not more than 16" centres. So there would be a bar close to any control joint.
RE: Retaining Wall