[Kameelyon]

Hey,
Thanks, in advance, for any help you may have for me. Started building a tiered retaining wall in my backyard. I am using the pavestone windsor wall block. Plan was to have two 2' tiered retaining walls with the appropriate 4' between them. Halfway done with the 1st tier and am thinking of going straight up to the 4' point (11-12 courses). A number of reasons going into this decision. Pavestone gives a maximum of 7 courses for this product. I believe I have done the base very well. 4-6 inches of crushed stone and and layer of paver base. 1st 3 courses are perfectly level side to side and front to back. I have a full course below ground. Wall is 20' in length then turns and goes 12'. I plan to use geogrid every other layer (or similar product). Obviously, manufacturer has good reasons for their limitations, but if I were just going to 8 courses I think we'd all agree it would be fine, Right? Do you think I can go to 11-12? Has anyone done this?

 

[Leah Frances]

According to your post, the maximum the manufacturer allows is 7. I disagree that 8 would be fine - that's a greater than 10% increase over what is allowed. And I REALLY disagree that you should exceed the manufacturer's limit by more than 70%.

I haven't done this. The manufacturer uses a maximum number of courses for a reason. Exceeding them by even one course is a recipe for failure and or disaster.

It's time to stop your project and step back to do some more planning before you continue.

We can help with this.

 

[Kameelyon]

I understand your concerns and thank you for taking the time to reply.

Has anyone had any experience specifically with these blocks, Pavestone Windsor, and has anyone built a wall taller than the recommended 7 courses. Would love to hear from anyone who has, thanks.

 

[95025]

They say 7 courses largely for liability purposes.

Can you run 11-12 courses? Yes. Should you? Ehhhhh... I don't think I would. 8, maybe. 11-12? Hmmmm...


I've not done it, but I've seen 15'-20' walls built with these pavers/stones. Clearly, however, the people doing so are not your rank & file DIYers. And they're not just setting one course on top of the previous.

 

[concretemasonry]

Going over the magic 4 or 5 feet automaticially puts you in the class of an engineered wall and not a landscape wall. - It must be engineered.

If you are in a code area or and area with zoning, you could be required to tear down the ENTIRE wall and start over again.

There is no problem going higher, but it must be engineered for the soil conditions because of the huge problems with the wall resistance and liability on both sides of the wall. I have seen curving retaining walls 15 miles long with varying heights from zero to 40', but they were enginered to determine the geo-grid spacing for the particular type of soil reinforcement used. - How did you determine the amount, length and spacing of geogrid you decided to use?

I don't remember what type of retaining wall system Pavestone uses, the the major 4 systems that are licensed have extensive testing and approvals from DOTs. The copied systems are definitely different in some ways to avoid the performance requirements that are globally accepted.

You idea of tiering the wall is good both from a common sense and landscaping perspective.

Dick

 

[95025]

Thanks Dick - excellent advice!

 

[Kameelyon]

Going over the magic 4 or 5 feet automaticially puts you in the class of an engineered wall and not a landscape wall. - It must be engineered.

If you are in a code area or and area with zoning, you could be required to tear down the ENTIRE wall and start over again.

There is no problem going higher, but it must be engineered for the soil conditions because of the huge problems with the wall resistance and liability on both sides of the wall. I have seen curving retaining walls 15 miles long with varying heights from zero to 40', but they were enginered to determine the geo-grid spacing for the particular type of soil reinforcement used. - How did you determine the amount, length and spacing of geogrid you decided to use?

I don't remember what type of retaining wall system Pavestone uses, the the major 4 systems that are licensed have extensive testing and approvals from DOTs. The copied systems are definitely different in some ways to avoid the performance requirements that are globally accepted.

You idea of tiering the wall is good both from a common sense and landscaping perspective.

Dick

Hey Dick,

Thank for replying. I should have provided more info. The blocks I am using are 4" high. 12 courses puts me at 4 feet and 11 courses keeps me under. Obviously, nobody can know if what I am thinking of doing will work or not, but does staying under the magic 4' make success more likely? You should also know that the wall will be about 30' long and will only hit the 11-12 courses in about 12' of that. Thanks again.