How to lay a patio
No matter what your project or materials you are using, if you have decided to do it yourself there are a number of factors you need to be aware of and important steps you need to take. Here are some examples of the steps required to cover the most basic patio paving installation.
Before you start …
Draw a simple plan of your home and garden, sketching where you would like areas to be paved. Once your plan has been finalised, lay out lengths of string to mark out the dimensions of your purposed patio in position. When you are happy with this, let the digging commence.
Step 1: Site Preparation –
Mark the pegs beforehand to indicate the depth and remember to allow for a gradual slope away from your property. Using the tape measure mark out the patio area. Check the corners, using a builders square. Removing topsoil is easily done using an edging iron and cutting the turf into manageable squares. Simply scoop with a spade and remove using a wheelbarrow and skip.
The excavated depth should be 150mm or 6 inches from the finished patio level. Measure the final depth of excavation using the pegs and strings.
Check the depth at the edge using a tape measure. Compact the soil with the Vibrating Plate Compactor and re-check the overall depths and slope of the area using the pegs and spirit level.
If you find soft spots in the soil, further excavation may be required. These spots can then be filled and consolidated with sub-base material.
Check all 90° corners and depths thoroughly before putting down the sub-base material.
When using excavation machinery please follow the manufacturer’s guidelines including acceptable levels of exposure and in particular use ear protection.
Step 2: The Sub-Base –
Having tipped the sub-base material into the laying area, rake into position to a consistent depth of 100mm or 4 inches.
Once the area is covered, check the depth using a spirit level, pegs and string line.
Compact the area using a Vibrating Plate Compactor, making sure the entire area has been compressed at least twice. Check again for any sinking areas. If this occurs, an extra depth of sub-base material should be considered.
Once the sub-base is smooth, flat and to the appropriate level, check the drainage slope with a straight edge and spirit level.
When using the vibrating plate machinery please follow all manufacturer’s guidelines including acceptable levels of exposure and in particular use ear protection.
Step 3: Preparing the Mix and Laying Paving Flags –
When preparing the cement mix, please avoid direct handling of cement, always cover your skin.
Either using the cement mixer or wheelbarrow and shovel, prepare a mortar mix of 5 parts building sand, cement and add water to create a doughy consistency.
To check this is correct use the ‘snow ball’ test, pick up a handful of mortar mix and squeeze into a ball, when you let go the mix will retain its shape without oozing water or falling apart.
Starting in the corner, trowel a bed of mortar to cover the area intended for the first paving flag. The depth of the mortar bed should be approximately 35-40mm. Level off but ensure the mortar is not compact as you want the flag to sit within the mix about 10-15mm deep.
Remember when lifting and carrying paving units always consider the weight before attempting to lift. If it is heavy, get help. Take care not to trap fingers whilst handling paving units.
Lower the first paving flag into position, holding it diagonally will make it easier to lower it. Settle it cleanly into the mortar without sliding it about so a good bond forms between the mortar and paving flag.
Line up the paving flag with the string lines and gently tap it into the mortar using the rubber mallet.
Repeat the process, continuously checking against the string line. Also, use the spirit level to check the surface is at the correct level.
Check that no edges are standing up proud simply by running your hand over the joints. Ensure consistent gaps, ideally of 10-15mm between the slabs.
Leave the slabs for at least 24 hours so that the sand cement mix can set.
Step 4: Cutting –
Great care is needed and it is essential to use equipment specially designed for this operation. Diamond disc cutters with water suppression are ideal. They are readily available at your local equipment hire store.
Check you are wearing good personal protective equipment for this activity.
Mark the paving flag surface with the intended cutting line for guidance. Place the paving flag on a platform and carefully saw using a diamond disc cutter.
When using cutting equipment please follow all manufacturer’s guidelines including acceptable levels of exposure and in particular use eye protection.
Step 5: Pointing –
You can either buy ready mix compound or, using the shovel and trowel, prepare a jointing mix of 5 parts building sand, cement and water to a damp, semi-dry consistency.
Firm it into the joints using the trowel and finish with the pointing iron, compacting the mix into the gaps and producing neat grooves.
Carefully remove any excess pointing material using the trowel and yard broom, ensuring no residue is left on the slab surface.
Materials and Tools Checklist
The key to starting off this style of project is the equipment, correct tools and materials for the job and having them all close to hand. Quantities of the following materials will vary depending on the size and sub-base requirements of your patio.
- Sharp Sand
- NGM Blocks Concrete Bags and Mortar
- NGM Blocks Dried Sand
- NGM Blocks Paving
- Pointing Tool
- String Line
- Rubber Mallet
- Screeding Rail
- Spirit Level
- Tape Measure
- Yard Broom
- Vibrating Plate Compactor
- Block Splitter or Diamond Disc Cutter
- Mini Excavator (Optional)
- Cement Mixer (Optional)
Please use Personal Protective Equipment when carrying out this work, such as safety shoes and gloves. Gloves, Safety Goggles, Dust Mask, Ear Defenders, Knee Pads.