Memo to Tilers for tiling on to waterproofing Membranes using
FLEXI WALL 'n FLOOR 2 PART ADHESIVE
Preparation
1) Tiling should be commenced onto waterproofing membranes only after sufficient curing time has been
allowed for the membrane. Do not tile onto uncured membranes.
2) The membrane should be cleaned down, removing any dust or contaminants, which may have settled due
to building activity etc after installation.
3) Some membranes which have been exposed for long periods of time to the suns ultraviolet rays and that
have oxidised, will require recoating. Seek the manufacturers recommendation on this.
Mixing of Flexi Wall ‘n Floor 2 Part Adhesive
1) The correct ratio for mixing of the adhesive on a stable solid substrate for decks when adhering tiles or
stone is:
1 Part Flexi Wall ‘n Floor 2 Part Liquid
2 Parts of Flexi Wall ‘n Floor 2 Part GENERAL PURPOSE Powder
This equates to 1 x 15 litre Wall ‘n Floor Liquid and 2 x 25 kg bags of General Purpose Powder. No water
addition to the liquid is required.
2) Because the product relies on hydration of the mineral and pozzolanic components in the powder, excess
water within the polymer liquid is usually lost through porosity either via the tiles or surface
substrate. However, membranes are totally impervious and 99 % of the time a highly vitrified tile is used (low
porosity), therefore the excess water which will not be hydrated out, will take a lot longer to escape, and
therefore slow down the cure time of the adhesive.
3) On an unstable substrate (e.g. a plywood deck with movement or in areas where expansion and contraction
is going to be a factor) or when using highly vitrified tiles a more flexible mix with greater shear modulus
capability is achieved when using the above ratio.
4) Always observe the rules relating to Wet Tack, Pot Life, and Open Time
1) It does not matter with what adhesive you are using onto which type of waterproof membrane, always ensure the tiles are bedded 100 % into the adhesive. This is simple good tiling practice onto membranes. 2) The adhesive should not have notched trowel lines evident. The reason for this is, if there is water ingress (e.g. rain) the water becomes trapped under the tile. This slows the cure rate down and consequently when it is grouted, the water will be entombed. If the notched trowel lines are not there and the tile is bedded 100%, water cannot enter under the tile.
Application
It does not matter with what adhesive you are using onto which type of waterproof membrane, always ensure the tile or stone is bedded 100 % into the adhesive. This is simple good tiling practice onto membranes.
The adhesive should not have notched trowel lines evident and stone should not be spot adhered to walls.
The reason for this is, if there is water ingress (e.g. rain) the water becomes trapped under the tile or stone. This slows the cure rate down and consequently when it is grouted, the water will be entombed.
Entrapped water can cause a pressure cooker effect on hot days, which can soften a membrane.
If the notched trowel lines are not there and the tile is bedded 100%, water cannot enter under the tile.
Control Joints
Control joints must be transferred from the substrate through the stone, brick slip facing or tile. They should not be filled with grout, but with a recognised and preferably colour matched silicone designed for this purpose.
Curing of the adhesive on membranes under a highly vitrified tile
The initial set of the adhesive will take place in the first 24 - 48 hours, dependent on temperatures and weather conditions. The porosity of the tile is another factor, however as mentioned before, highly vitrified tiles are the most commonly used and have very little porosity.
The adhesive at this stage will be like shortbread, still slightly moist and crumbly.
It will take at least 10 -14 days for the adhesive to get its ultimate flexibility and bond strength when entombed between an impervious membrane and a highly vitrified tile, under normal ambient curing conditions.
Grouting
Grouting can commence as soon at the tiles are trafficable.
Usually after 48 hours - the initial set phase.
It is important to grout as soon as practicable, so water ingress is minimised. If the tiles are bedded into the adhesive properly (100% without notched trowel lines), water ingress under the tiles is not possible.
Avoid point loading tiles by walking on corners (highly vitrified tiles have poor rotation and flexibility) and tiles could pop.
Some tilers lay planks or boards out to disperse their weight over an area.
Note:
Flexco (NZ) Ltd can only give recommendations on the use of its adhesive, and cannot control its use by tradesmen. Flexco (NZ) Ltd is not responsible for engineering, and specific or architectural design and specification
Flexco (NZ) LTD will not be responsible for adhesive washout due to water ingress from rain or sprinklers prior to cure of the adhesive.
It is the subcontractors responsibility to ensure there has been sufficient cure time of the adhesive allowed prior to traffic, and that all precautions are taken to avoid ingress of water from rain etc during the cure phase.