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What products should I use to adhere an Akril or Marmox shower base to cement sheeting, concrete or timber?

An SMX Polymer such as Soudal T-Rex or Multibond should be used to ensure proper adhesion.

How do I prime a surface when I am going to use Gripset 51 on a retaining wall?

For most applications, you can use Gripset 51 as your primer, by mixing 1 part Gripset 51 to 3 parts water. Once dry, you can then apply the first undiluted coat of Gripset 51.

How can I prevent water leaking through our tiled balcony into our living area?

One option is to apply a clear penetrative sealer such as Sealtight onto the tiles and grout. Remove any excess sealer that is not absorbed with a cloth as you work. The sealer will penetrate into the grout (and tiles if they are porous), making the area water repellent. It is of note that any cracked grout or tiles must be either repaired or replaced prior to work taking place.

Alternately, you can use the Clear Waterproofing Membrane on top of the entire area.

Can I use a trowel to apply Planiseal 88?

The first coat of Planiseal 88 must be applied using a brush. The second coat may be applied by either brush or trowel.

What factors can affect the drying and curing times of waterproof membranes?

  • Ambient air temperature
  • Temperature of substrate
  • Humidity
  • Moisture content of substrate
  • Air flow
  • Thickness of the membrane
  • Type of membrane used

How do I tell when a primer is ready to accept the first coat of membrane?

After the time specified by the manufacturer, check the primer by touching it. If the primer is dry then it is ready for the first coat of membrane. Drying times can vary depending on multiple factors not least of which is the specific primer used.

What is Crystal Sealer, and how is it used?

Construction Chemicals Crystal Sealer is a cementitious product designed to be applied to concrete which is leaking water. In time it will grow crystals into the concrete following the water paths through the concrete capillaries and eventually waterproofing said concrete. It is applied by brush in approximately 2-3 coats and then requires watering once every 24 hours for three days for to promote crystal growth.

When should an epoxy primer be used?

An epoxy primer such as Gripset E-60 should be used under a number of circumstances, including when working over uncured cement based products as well as on substrates that have a high moisture content. It can also be used to prime non-porous substrates (such as PVC, metal or Scyon) that may normally be very difficult to adhere waterproof membranes to using conventional water based primers.

I have been recommended to use Duram Multithane, but I understand it is solvent based. What do I need to know when using it?

Solvent based membranes such as Duram Multithane generally require that the substrate be perfectly dry prior to application of the membrane or require an epoxy primer to be used if the substrate is damp. Solvent based membranes also contain xylene and isocyanates which can be detrimental to human health and the applicator should wear appropriate breathing apparatus whilst working with them. Tiling on solvent based membranes can also be difficult, and it is highly recommended that the manufacturers data sheet be referred to prior to tiling.

How do I select the right primer for a job?

Most waterproof membranes have specific primers which are manufactured for use with them. In certain circumstances alternative primers need to be used such as epoxy, and you should consult the product data sheet or your waterproofing experts if in doubt.

I need to waterproof over a screed, how long should I allow the screed to dry before I can apply a waterproof membrane over it?

It is important to note that just because a screed is touch dry, does not mean that it is ready for an application of waterproofing product over the top of it. A screed has to be fully cured, prior to membrane application, and curing times can vary dramatically due to a number of factors, including thickness of the screed, specific mixture of the screed, humidity, air flow and temperatures amongst other things. If you are unsure as to the curing status of a screed, it is highly recommended that an epoxy primer be used prior to applying a waterproofing membrane.

As a very general rule of thumb, you should wait a bare minimum of 24 hours for every 10mm of screed thickness or a minimum of 72 hours for screeds thinner than 30mm. This is a basic guideline only, and in reality screed curing times have varied wildly; in some extreme cases taking up to 30 days to fully cure. The Australian Standards state that screed can take up to 1 day per 1mm of screed thickness to fully cure.

If possible, use a moisture meter to check the moisture content of the screed – you’re looking for a value below 8% to ensure against membrane failure.

If in any doubt whatsoever as to the curing status of the screed, always use an epoxy primer or a product such as Gripset P10 as a vapor barrier prior to membrane application.

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