cj7
Gold Member
Sometime in the future I may have to replace a retaining wall. So I thought I would start to study up on them now. Does anyone know of a site that is a good guide in the designing of a retaining wall?
retaining wall
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sdkubota
Platinum Member
Depends on how high the wall will be...3' - concrete blocks, 20' - heavily reinforced concrete wall. There is a lot of science on proper wall design and an incredible amount of pressure against them if not properly designed and drained. Most retaining walls fall over. 
KennyG
Elite Member
For short walls, the landscape blocks that overlap do amazingly well. Beyond that, it get's into an engineering project. As mentioned above, the forces are much higher than you would expect and requires more than just building a wall. In addition to making sure you drain well from the base, incorporate some type of tie back system if you are looking at more than 3 or 4 feet high.
nwngunner
Silver Member
you have to take frost expansion in to your walls as well. We had a barn that the back wall was a retaining wall and the frost broke it like it wasnt even there. That was 8inch poured wall as well. More details on the wall your build and we might be able to help you.
vtsnowedin
Elite Member
Lets start with what is there now and how long it has been there and how well it did it's job?
gumshu
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These work pretty good if installed correctly. I've put in a few hundred feet of the Europa style.
Segmental Retaining Wall Types and Styles
Segmental Retaining Wall Types and Styles
MN Charlie
New member
The modular concrete retaining wall blocks can do some impressive things IF they are built to the block manufacturer's specifications. Many times they are not and people blame the wall material. I work in an engineering and architectural office and have drawn plans for several such wall and they are still doing well today. There is one that has a driveway just a couple of feet back from the edge of the 10-12 foot tall wall and even with the daily vehicle traffic it's holding up well 15 years after it was built.
As was mentioned by nwngunner, frost action needs to be taken into account and along with that, drainage is important. The wall backfill needs to be granular material that will drain (not too many fines) and drain tiles need to be installed at the base and possibly at higher elevations as well.
One thing that is super critical for the actual soil retaining properties of the wall is the use of geosynthetic mesh fabric extending well back into the hill, anchored to the retaining wall and anchored into the hill with well compacted granular material that interlocks with the geosynthetic.
Keystone is one manufacturer of modular concrete retaining wall blocks and they have some very good information about how to properly design and install their product. You can get a good idea of what to expect by looking at their installation instructions you can find on this page:
Keystone Retaining Walls
Disclaimer: Other manufacturers will have similar, though probably slightly different, instructions and requirements. If you go this way, be sure to read and follow the correct instructions of the manufacturer of your retaining wall blocks.
As was mentioned by nwngunner, frost action needs to be taken into account and along with that, drainage is important. The wall backfill needs to be granular material that will drain (not too many fines) and drain tiles need to be installed at the base and possibly at higher elevations as well.
One thing that is super critical for the actual soil retaining properties of the wall is the use of geosynthetic mesh fabric extending well back into the hill, anchored to the retaining wall and anchored into the hill with well compacted granular material that interlocks with the geosynthetic.
Keystone is one manufacturer of modular concrete retaining wall blocks and they have some very good information about how to properly design and install their product. You can get a good idea of what to expect by looking at their installation instructions you can find on this page:
Keystone Retaining Walls
Disclaimer: Other manufacturers will have similar, though probably slightly different, instructions and requirements. If you go this way, be sure to read and follow the correct instructions of the manufacturer of your retaining wall blocks.
Mybuddy's wall fell over because they didn't compact the backfill and didn't make the geotextile extend long enough into the hillside. The new wall is set back every row and the corners are radiused instead of being sharp.
newbury
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MN Charlie
New member
My brother-in-law's mother had a wall built along her driveway and the installers told her that they didn't need to put in more than a 2-3 foot deep geosynthetic for it to hold. "Conveniently", that was as far as they could dig without removing the bituminous pavement on the driveway... One year later and they were out re-stacking the wall under warranty because it had visibly shifted. Another year later, warranty expired, the wall had shifted again. It was replaced properly with 10 foot deep geosynthetic and the driveway re-paved. It's holding up well now.
Here's a super scary looking use of modular retaining wall blocks here in town:
Bing Maps - Driving Directions, Traffic and Road Conditions
Those terraced walls are each over 15 feet high and then the built a house on top of it! They much have a LOT of confidence in those blocks!
Here's a super scary looking use of modular retaining wall blocks here in town:
Bing Maps - Driving Directions, Traffic and Road Conditions
Those terraced walls are each over 15 feet high and then the built a house on top of it! They much have a LOT of confidence in those blocks!