Rock FAQ

Common questions when looking at using decorative rock:

Question: How much rock do I need?
Answer: There are many answers but the one that we have had the most success with is one ton of rock will cover 100 ft2 about 2 inches deep. We have never had anybody call us back and complain of too much or too little using this rule of thumb. One ton of rock will generally fit into a normal size bath tub if you need to think in terms of volume.

Question: What sizes of decorative rock are there?
Answer: In general most decorative rock is crushed rock derived from a bigger rock source. The rock is mined and run through a set of crushers to reduce the size down to the most common dimensions of ¼ inch, 3/8 inch, ½ inch, ¾ inch or 1 inch and sometime 1 ¼ inch. The range of sizes within the nominal size varies depending on the mine and equipment used to crush it. Some people also like to install Rip-Rap which is a larger rock 3 to 8 inches as an accent or dry river bed. It is more work to install and potentially more money to deliver but adds another dimension. Another accent used by a lot of people is the use of boulders. There are many kinds of boulders, ask your sales person what is available if you want to use these. Occasionally they can be added to the ‘load’ of rock coming and will be mixed in with the rock you’ve ordered. Don’t go overboard with size if you are going to move them by hand, boulders get heavy fast and are then harder to move.

Question: How does it come and how do I install it?
Answer: Normally the rock comes in bulk, delivered with a dump truck. From here the installer is responsible for spreading the rock. If you do it yourself be prepared for some heavy work. For small quantities a wheel barrow and a shovel my get you by. For large jobs a small skid loader can be rented from any rental yard. Generally the rock is moved around and raked or pushed until it’s about 2 inches deep. You may also want to involve family members, friends and relatives if you are doing it yourself and it’s a big job. Also be realistic when the material is being delivered. A dump truck is not going to be able to get through an 8 foot gate, go over soft grass, under some trees and then loop around the house over some pool kool decking and drop right on the space you need it in the back yard. Most trucking companies don’t like to go over the curb in front of the house for legal reasons. Some may ask you to sign a waiver that you take responsibility for any damage done to the curb or sidewalk if you want it dumped directly on your property. In most cases the rock is going to go on the street in a pile. You will need to check with the city or HOA for what kind of markers or cones that you need. If you have a big yard and no issues with curbs, grass, trees, water mains, sprinklers etc. the rock company can be pretty accommodating about where you want the rock. Work with them and they will work with you.

Question: How is the purity measured?
Answer: There are several common measures used to indicate how much fines are mixed in with the size range of rock being requested. Fines are essentially dirt which goes through the screening process and ends up in the final product even though it is considerably smaller. The most common class of rock here is ‘Screened’ which has between 20% and 40% fines. This may seem high but the rock in this class should look like the rock you picked. In other words if you picked 1 inch screened rock, from a few feet away it will look like 1 inch rock. Most of the rock in the rock gallery is screened. The next most common class in ‘Minus’ where up to 80% of the material is fines. This class of rock will normally look like a pile of colored dirt with a few rock of the size you ordered in it. A 1 inch minus rock will still look like a pile of fine dirt with a few 1 inch pieces in it. Other than these two classes some mines used ‘sized’ which has less fines than the screened material and ‘washed’ which is more pure again.

Question: The rock is not the color I ordered?
Answer: Rock is a natural product and as such there are going to be color variations depending on what part of the mine the rock company is working. It is virtually impossible to guarantee the color unless the customer is there when they are mining it when the sample is taken. Having said that, the color difference between a sample and actual delivered should not be outlandishly different but a shade or two is not abnormal.

Question: How do you keep weeds from growing in the rock?
Answer: There are several solutions out there and all work with various degrees of success.  From the below, we carry the plastic and the fabric and can source the pre-emergence.

- The first and oldest is using a landscape plastic. Normally this is a thick black plastic that goes over the bare ground and the decorative rock is spread over the top. It tends to work well in the early life of a rock lawn and looks frayed at the edges and comes up in spots over time. It also traps water underneath as it doesn’t breath.

- Second is landscape fabric. This works similar to plastic as it goes over the ground and under the rock. It is less sun sensitive and easier to install, it breathes, and works by not allowing weeds to grow through. It may suffer as well from coming up at the edges or showing bald spots over time.

- Third is using nothing and relying on a pre-emergence or common weed and grass killers to prevent weeds or grass from growing. A pre-emergence is put down on bare ground and creates a zone where nothing will germinate. It does need to be re-applied periodically depending on rain and porosity of the ground. In desert climates with low rainfall some people are using nothing and killing the weeds or grass as it comes in. This method works as long as you stay on top of it and kill the weeds or grass early and regularly. If you wait too long you may end up trying to kill large sections and then you will need to spend time removing the dead growth because it got so large that it is all intertwined with the rock.