Raised stone patio

Hello,
I am preparing to build a stone patio with a portion of it raised (by 18'). Three concerns below that I am seeking inputs for:

I have been researching for the retaining wall around the patio and found some info which had some conflicting results - Some conclude that I can get away with not having to provide a deep concrete base for the wall and some say I need one. I live in Indiana and am concerned about the breathing of the ground through the season causing issues with the wall....my plan was to dig in to about 10 to 15" (4-6" base + 2" levelling sand + 1.5 X the wall brick size)
Would appreciate your inputs....

Also, I was planning to use the dirt that I dig out from the non-raised section to fill into the raised section to about 6". The remaining 12" will include the base, levelling sand and the patio pavers. After reading through the sites, I am concerned about filling in with loose dirt. I was going to use the compactor to lay it down and was thinking of just doing multiple passes before I start pouring the base....is this a good idea? May I still have settlement after taking the above steps?

The third concern is that we are just getting out of a cold and wet winter. Yard is still wet. Folks have advised me against beginning work when it is wet...should I wait till it dries out completely.....how soon before I can start?

Best regards,
AB

 

First, is your patio going to be raised 18' (feet) or 18" (inches)? It's a huge difference. 18" is within the scope of a DIY project while 18' is best left to professionals with engineering to support what they are doing.

Regardless, using earth as fill under a patio can be dangerous. It is difficult to properly compact soil/earth fill so it does not settle over time. It can be done but does it require the right soil and moisture content so it can be compacted. Depending on the equipment you use the soil is put in in layers with each compacted before the next layer. A safer but more expensive approach is to fill with clean crushed stone which naturally assumes a pretty high compaction ratio so chance of settling is minimized.

 

Hi, thanks for the response Pilot Dane...

To clarify, it is 18" (inches)...not 18 feet.

I have been looking into filling the raised section with crushed rock as well....it gets a little more expensive...also, I wanted to make use of the dirt that is dug out of the other flatter section. One of my colleagues who does this type of work told me that maybe if I can get a few many passes with the compactor going into the dirt, then it may work and as you said a couple inches at a time though.

Also, there is some dirt that was alread spread the area (~ 3 to 4") and I want to explore my options before I start working around or with this dirt.

Any tips or tricks to minimize settlement while using the dirt would be appreciated....I live in Indiana and over the past summer while digging for another project realized there is a lot of clay and had to dig about 2 feet before I get to softer soil.

Would appreciate any comments or suggestions.
Best
AB

 

To minimize settling you have to compact the soil so it can't or won't settle in the future. And it sounds like you are familiar with the technique of spreading out a few inches of soil and compacting before adding more soil.

I like using dry stack retaining wall blocks. Not the small ones you get from garden centers but the larger & heavier commercial duty ones. They are set on a foundation of compacted gravel. While heavy it is a very doable job for a DIY'r. And because you are not pouring concrete you can do the work in stages as time permits. I am partial to Keystone brand mainly because it's locally available and I've done a lot of retaining walls and patio edges and mostly use the original Compac blocks which are listed under structural wall products but they have others that are more attractive.

 

Thanks for the tips again...

About the dry blocks for the retaining wall, I am planning to use the heavier ones as you suggested. However the ones that we liked do not have a lip or key way in them to resist drift under side load from the compacted dirt/gravel within the raised section. Folks told me to use the block glue to secure these blocks. The intent is to avoid the edges giving way with traffic. These blocks were about 25lbs each so am of the opinion they are heavy enough...but would you have any concerns with using no lip retaining blocks?

 

I only use the heavier blocks (about 85lbs each) that have retaining pins. I have not seen the smaller blocks stay in place long term even with glue and in our relatively mild climate. I can only imagine how they handle your freeze thaw cycles.

 

Use only the retaining wall block that have some sort of a key, lip or pin to create a possible resistance to sliding between each other. Adhesive is not a positive and durable substitute.

All of the 4 major product lines (Allan Block, Anchor Block, Keystone and Versalok) offer acceptable units in different sizes and the use and installation instructions on their sites. They all have products that are approved and used by many states, counties and municipalities.

This type of a wall is a "flexible wall"so it can move ever so slightly to resist the soil and moisture changes . The should never be used on a concrete footing (even for 20' FOOT high walls) and they do not allow the use of mortar. The type of units and installation methods are the reason for the millions of units used domestically and internationally.

Any adhesive eliminates the ability of the wall to move, perform as needed and be more durable. Adhesives create an inferior wall.

Dick

 

Thanks everyone! am beginning work on this project...will post final pictures when done...sure will have more questions in the mean time...