Brick Slips

GUIDANCE FROM – CLAY BRICK & PAVERS MANUFACTURERS

INTRODUCTION
What is a brick slip? We like to refer to a brick slip as the solution to achieving the genuine look of clay brick virtually anywhere you wish to put brick. It is a piece of brick approx 18mm thick, cut from the face of a brick using a diamond saw; glued to a substrate as you would for a ceramic tile.
The thickness of the brick slip is important. It should be a minimum of 15mm, and a maximum of 25mm, the optimum being 20mm; stone slips are thicker. There are four basic reasons for this requirement: to keep the weight to a minimum; to provide a smooth surface (free of the holes) upon which to spread the glue; to avoid forming a pocket that can trap moisture that could freeze in the winter or boil in the summer creating possible problems; and to have sufficient thickness to achieve a suitable mortar joint.
CUTTING BRICK SLIPS
It is desirable to cut the brick slips on site. The advantages of doing this are: that you know the slips have come from the same batch number as other bricks on the job; wastage is kept to a minimum; and there are no breakages due to transport. There are approx. 50 brick slips per square metre of wall. The slips may be cut as stretchers, headers and even right-angle slips (L-shape) to go around corners, and use up the sides of windows. If the brick is a rumbled brick add approximately 3mm to the thickness of the cut to allow for the rumble.
INSTALLATION
The brick slip system is an excellent system, provided all involved follow the specifications, of which there are three components involved: the brick slip itself; the substrate it is going on; and the adhesive used. If the installation is not carried out correctly there is a high risk of failure, which could be very expensive to repair.

THE BRICK SLIP

  • Cut the brick slips to the required thickness; 20mm recommended.
  • Ensure the slips are dry prior to installing them.
  • Remove all dust from the back of the slip with a damp cloth, prior to applying adhesive.

THE SUBSTRATE
If the substrate is concrete panels or concrete blocks, movement control joints need to be installed through both the concrete substrate and the brick slips that are adhered to the surface.
PLEASE NOTE: Over recent years some major manufacturers/suppliers of fibre-cement board products have withdrawn their approval for brick slips to be installed on their products. It is important that approval is obtained from any supplier/manufacturer of a fibre-cement board as to its suitability as a sub-strait for brick slips prior to proceeding with design and installation.

THE ADHESIVE
Although there are several good adhesives on the market we recommend one of the following:

Laticrete NZ provide a full instruction sheet for fixing brick slips using the Laticrete System; the following are the major points covered in these instructions.

SUBSTRATE SURFACE PREPERATION
IMPORTANT: If the substrate is precast concrete, it is essential that all ‘releasing agents’ have been thoroughly removed from the concrete prior to commencing laying brick slips and that all brick dust has been washed off the brick slip.

  • The surface must be clean, dry and free of contaminants. No primer is required, the waterproof membrane Laticrete Hydro Ban water proofing and crack prevention membrane provides a barrier.
  • Seal all joints by using a brush or roller to apply a thick coat of Laticrete Hydro Ban to a strip 75mm either side of the joint.
  • Immediately bed the reinforcing fabric bandage into the wet liquid to bridge the joint.
  • Coat the remainder of the wall with Laticrete Hydro Ban, and at the same time apply a second liquid coat over the reinforcing bandage. Note: 5 litre bottle covers 10m2; drying time approximately 12 hours.

APPLYING THE BRICK SLIP ADHESIVE
By just mixing with Laticrete 254 Platinum powder will make a high strength flexible and shock resistant latex thin-set adhesive – coverage 7.4 – 8.8m2 per 23kg bag using 6mm x 6mm notched trowel.

  • Mix 5:2 litres of fresh water with 23kg bag of Platinum. Mix until creamy and workable. Adjust quantity of liquid to achieve the proper working consistency.
  • Allow to stand for 5–10 minutes and re-mix.
  • Using the edge of a trowel, scrape a film of adhesive, working it into the substrate. Apply the adhesive to the back of the brick slip with the trowel, working it into the surface. It is essential that sufficient adhesive is used to completely cover the back of the slip with a minimum 2.5–3.0mm thick uniform adhesive bed.
  • Place the brick slips while the adhesive is wet and tacky. Take care to firmly bed the brick slips onto the wall substrate.
  • If mortar is being applied at the same time as the adhesive, bricks may be pointed as the job progresses. In other words, laid the same as if laying normal bricks. I recommend this method. If not, joints may be pointed once the adhesive has firmly set. Note 10mm spacers are required if this method is adopted.

GENERAL COMMENTS

  • It is not essential but we recommend a waterproofing product (Surfapore R) be applied over the wall surface once dry and completed, for extra protection.
  • It is essential that control joints be installed where brick slips abut a different cladding, either horizontally or vertically or as required.

PLEASE NOTE:
The CB&PMA and its members take no responsibility for the installation of brick slips; the information provided here is done so as a guide for our customers, and to aid the process of installing brick slips. It is the responsibility of the owner, the builder, the bricklayer and the architectural designer to ensure that acceptable and correct procedures are followed and carried out by professional who know what they are doing.