An easy to follow guide for placing and preparing your foundation material
In my last blog I spent some time running through the options of materials suitable for your landscaping foundations. Once you have chosen the material that best suits your job, whether that be pit sand, quarry dust or GAPs, you will need to place and prepare that material in readiness for your finished surface – either pavers or concrete.
To help with this, here’s a step by step process for preparing a foundation for laying pavers. The steps will be the same for concrete pathways and driveways, but you will need to erect boxing to contain the concrete. You may also need a base course if you have a deep foundation and the “smoothness” of the finished foundation surface isn’t so critical.
When it comes to correct placement and preparation, one word sums it up …COMPACTION. A solid foundation is key to providing a finished surface that will look good and remain intact over time.
Follow these 11 steps to achieve a great foundation:
1. Mark out the area: Prepare the area using a string line or spray can of marker paint (both available from WDLS). I prefer string lines using construction profiles to accurately establish the area and finished heights of the work to be done. Remember to allow yourself some extra “working room” when marking out.
2. Clear the area: Excavate to remove all topsoil so that a hard clay base is exposed.
3. Do your calculations: Calculate the volume of foundation material you need to back fill the excavated area. The calculation is the length x width x depth of the excavated area. Multiply that figure by 1.3 to allow for compaction of the material. Calculations should be done in metres because you will order your volume of material in that unit. Here’s an example for a job 5 metres long, by 3 metres wide by 0.3 metres deep; 5 x 3 x 0.3 x 1.3 = 5.85m3. Your material requirement will be rounded up to 6m3.
4. Choose your material: Decide on which material best suits the job you are doing. My choice would be quarry dust, but pit sand is an option.
5. Collect your material: WDLS has free courtesy trailers available that can carry up to 0.5m3 per load, or we can deliver larger volumes to your site. We are happy to provide an estimate of cost if delivery is required.
6. Spread the first layer: Spread a layer not greater than 150mm of your foundation material across the bottom of the excavated area. Roughly level the material using the back of a rake or similar.
7. Dampen the material: If the material is dry, sprinkle water over the area until it is damp (not saturated) throughout.
8. Compact the material: Compact your newly laid material until it is hard. WDLS have a compactor available for hire if required.
9. Add an extra layer: Add more 150mm layers of material, level, water and compact as required until a level slightly higher than that required is reached.
10. Skim excess material: Working off the string line and profiles, skim the excess foundation material from a section of the excavated area at a time to achieve a smooth hard surface over the entire area. I find a straight edge trowel and square-mouth shovel are good for this stage.
11. Lay your pavers: Once you have a smooth solid base over your entire job you are ready to lay your pavers or concrete.
These are the basics of foundation material placement and preparation. If you have any further questions, Dave or I at Watson Davies Landscape Supplies are always available to help.
Wishing you happy and creative landscaping