6x6 Retaining Wall

My landscaper gave me a quote for the construction of two walls 40 feet (all 4 feet high) from 6x6. He said that the code does not require him to return to fill with gravel. Should I be worried? He said that if he put in a block wall, he would be back filled. Why would it be?

You still need to fill unless it is the construction of your wall with a retaining wall completely new technique. Like maybe he is digging deep steel beams into the ground? I doubt it! I would get a second opinion, the gravel is needed to mitigate the effects of water infiltration and soil shifting.

If you have an idea of the nature of the materials used, you can estimate your cost of materials. (See below)

Get a different landscape for the estimates. I found 12 different contractors with 10 different ideas, but the city code are always right, when I was building a covered porch.

If you live in any place where the product freeze-thaw and the wall has the ability to "shift", I have a fill and compacted sub base too. The gravel fill to ensure that the retaining wall does not separate the soil mass, particularly since the excavation disturbance that existed before compaction.

Code can not require it, but it is convenient construction to ensure high durability of the retaining wall. You might also consider using a geotextile product (geogrid), which acquires most of the wall in place and prevents it from collapsing face first. Of course, it depends again on your site and engineering, but it is just a cheap insurance / building the wall will not fail. Manufacturers recommend that anytime a block wall is greater than 3 feet.

each municipality has its own code. I live in CA. Retaining walls over 4 feet. must be designed, so you should be clear on this point and the code probably does not provide a rule to fill. the rule of the CA. landscape standards states that for every foot of height of a retaining wall, you must provide a supporting foot underground. If you choose to build from wood, the wall will be stronger if you set the vertical supports to the outside wall if you want the media inside the retaining wall, I suggest drilling and Fasten the bolts vertical surfaces. Should you choose to make building blocks cement, you should defintely a good foot L-shaped for added strength. Nevertheless, you should provide a drainage system to relieve hydrostatic pressure, which will build behind the wall. Good luck, hope this helps.