Interlock Cleaning and Maintenance

Interlock Cleaning and Maintenance

Interlocking, patio stones, flagstone, stepping stones or any hard surface will eventually get weeds and require cleaning out prior to regular maintenance.

Ottawa interlock pavers maintenance weedingCleaning out of weeds from hard surfaces can be done by:
1) Hand weeding to remove weeds, sand and debris using an L-shaped interlock weeding tool. Ensure to remove all soil, roots and debris prior to re-sanding. Very time consuming method.
2) Thermal weeding should be done by a professional so as to not burn and mark pavers. Weeds are burned out by using a propane torch weeder.
3) Horticultural vinegar application to kill weeds by acidity and dehydration. Horticultural vinegar is 10% acetic acid and thus 2x the concentration of household vinegar. Other herbicides-weed killers can be used to kill off and control moss, lichens and algae should this be problematic. Apply during dry weather. If thick growth then trim or scrape off first before application. Most treatments leave a residue to discourage the re-growth but this is of limited value if the environmental conditions aren’t changed
4) Pressure washing to force weeds out of cracks and crevices. A high-pressure sprayer applies water and cleaners between 600 and 2,000psi and at a rate between 22 and 45 litres per minute. The pressure loosens dirt and debris and pushes water from the surface.

After cleaning out the paver joints it is vital that the joints are re-filled completely with the appropriate jointing sand. If using jointing sand then sweep into all cracks and spaces prior to sealing. If using polymeric hardening sand then once sand is swept in it needs to be wetted accordingly to “harden”. For flagstone replace the stone dust and sweep in to fill the cracks and spaces.

Regular maintenance requires visual inspection of the joints between the pavers to determine if any sand has been lost. Joints with low or no sand should be topped up with sand and swept clean. Cleaning and sealing will discourage ants and weed growth in the joints as well as add new life to surface.

Weed Growth between Pavers

Weeds between pavers might be due to excessive space between pavers. The widened joints may be from lack of a stable edge restraint, loss of base pad or jointing sand. Do the necessary repairs to rectify the problem. For example if there is no snap edging to hold your interlocking then have snap edging installed correctly to decrease joint widths and hold pavers tight together and in place. When separation occurs and joint spaces between pavers enlarge then overtime soil will enter in creating conditions to support weed growth. Repeated cleaning maintenance will be required unless the joint widths are tight, soil between the pavers is removed and replaced with jointing sand and a sealer applied to the joints. Stabilizing the jointing sand with a sealer or use of polymeric hardening sand is the best measure for preventing weed growth. Always use sealers and joint sand stabilization materials that are specifically recommended for pavers.


When pavers are installed according to recommended installation procedures there will be little need for repair. Pavers in Ottawa are particularly susceptible to the combined effects of frequent freeze-thaw cycles and moisture. This combined with repetitive loads from vehicular traffic over time can result in settlement of the base and pavers. A common problem is settlement of individual or group of pavers near curbs, site fixtures, walls or at locations where pavers meet other surfaces. Settlement is often due to insufficient compaction of base materials especially in confined areas that are difficult to reach with mechanized compaction equipment during installation. Settlement can result as a loss of base materials as a result of insufficient drainage. Settlement can occur near downspouts where water flows directly onto the pavers. To repair settlement the paving units must be lifted and re-laid. To tighten spacing between pavers then lift and re-lay; complete with installation of snap edging to hold pavers tightly in place.


Efflorescence is a temporary phenomenon that occurs naturally on products containing cement. It appears in the form of a white deposit on the surface of the paver, often shows up in the first or second season after installation. Efflorescence is caused when soluble salts within the concrete evaporate and deposit on the surface; or when the concrete reaction components (calcium hydroxide) react with the atmosphere to produce the white film (calcium carbonate). The efflorescence crystals are not visible when wet but are when dry. Concrete products under damp conditions are more susceptible to efflorescence as the moisture aids the migration of the soluble salts to the surface of pavers. Efflorescence does not have any effect on the structural integrity or durability of pavers. Efflorescence is temporary and will disappear in time with normal weathering. It can also be removed chemically by using an acid washing agent. Specifically made efflorescence cleaners should be professionally applied.

For maintenance, repairs as well as installation of hard surfaces contact Harmony Gardens Landscaping – “creating harmonized spaces”.