Bosun Flagstones

Install Bosun Flagstone pavers, size 400mm x 400mm x 35mm thick in [Insert Colour/Texture/Finish].

or

Install Bosun Flagstone pavers, size 400mm x 200mm x 35mm thick in [Insert Colour/Texture/Finish].

Installation guidelines for Bosun Flagstones

Site Preparation

• All grass or other vegetation together with a 150mm layer of topsoil must be removed (enough to allow the thickness of your chosen pavers as well as the base & bedding courses). The area should then be well compacted.
• In order to prevent flooding or pooling of water a slight slope (min 1:50) should be made preferably directing water away from the building or into a drainage system.

Base course

• The base course will serve as the foundation for your pavers and will determine the lifetime and quality of the entire installation for years to come.
• Bosun recommends the base course of compactable material like G5. This layer should be 75mm to 100mm thick and be well compacted with a roller or large plate compactor maintaining the slight slope created in step 1.

Bedding course

There are two main options when it comes to the bedding course:

Option 1 - Individually prepared bed

• Individually prepare bed for each paver.
• The concrete bedding mixture should consist of good quality river sand in a ratio of about 6:1 with the cement.
• It is crucial for sand to be well draining. Ensure sand used does not contain a lot of fines as fines will retain water. Do not use building or plaster sand for bedding. These sands contain too much fines.
• The cement mixture should be able to compact it in your hand without it sliding through your fingers.
• Bosun recommends a bed of 40-50mm thick.
• Prepare a small section of bedding layer before each new paver is laid making sure the bedding course is level and provides a stable base for the paver.
• Have the bedding layer extend further than the paver so that the entirety of the paver is in contact with the bedding course. There should be no air pockets or spaces between the paver and the bedding material.
• When laying pavers into mortar, ensure that the pavers are wet. This is to stop the paver from absorbing the water in the mortar and compromising the strength of the cement mortar.
• Carefully lay the paver and check its levels correspond to the pavers around it. A rubber mallet may be used to make sure it is firmly in place.
• If the paver is still too low or too high, it has to be lifted and the bedding layer adjusted.

Option 2 - Screeded bed

• Prepare a screeded bed, 40 – 50mm thick for the flagstones to be installed on.
• A semi-dry screed mix consisting of river sand and cement is recommended.
• Screed the mortar carefully so that it creates a smooth, even surface (keeping in mind the recommended minimum slope of 1:50).
• Allow it to dry overnight in order for the screed to harden.
• Use tile adhesive to fix the pavers to the screeded surface.

Bosun recommends the application of a bonding agent to the back of flagstones in order for it to better adhere to the concrete bed.

Laying pavers

With both methods tile spacers should be used in order to create uniform grouting gaps. 6mm spacers are recommended for Bosun Hermetic pavers.

Use a heavy, non-marking rubber mallet to level pavers onto the chosen bedding material.

Grouting

There are two main options when it comes to grouting:

Cement paste

• Use a paste made with 4 parts plaster sand to 1 part cement.
• The area to be grouted must be wet before applying the cement-based grouting.
• Using a trowel, carefully work the paste into the joints.
• Tool the joints down with a pointing tool.
• Remove excess grouting material from the pavers immediately with a damp sponge.
• The sponge must be rinsed and squeezed dry after each wipe in order to avoid staining of the flagstones.

Specialised Resin based paving mortars

• Resin based mortars are imported and more expensive but their greatest advantages is that joints don’t disintegrate and crack like cement joints and there is no risk of staining as with cement grouting.
• The resin based mortar is mixed as per the manufacturer’s instructions. The slurry that created is pushed and swept into all the spaces between the pavers and allowed to dry. Once dried out a little the mortar can be brushed off paved surface.

Contact Bosun for more information on resin based jointing mortars.

Bosun does not recommend a cement slurry that is washed into joints.