SikaWall®-531 Smoothband

Every building element moves and all movement joints in the substrate must be replicated in the render finish, or cracking will appear.  If it is a timber frame, then the movement joints in the timber frame (i.e. between panels) should also be considered in the render, even if they are not replicated in the outer blockwork.

Yes, they can be repaired.  Please refer to our  ‘How to repair holes, Sika mineral render finishes’ technical information sheet for guidance.

The primary reason is air entrapment within the render and this is caused at application stage when the correct float and serrated spatula or derby tools have not been used to sufficiently aerate the render and break any bubbles to ensure there are no voids within the render.

Render should never be applied to a frozen substrate and the temperature should be 5° and rising before application should begin. Always protect newly applied render from freezing conditions. For more detailed information on cold weather applications, refer to the Technical Information sheet: Cold weather working - General guidance.

This is caused by incorrect application of render, including: applying render to a wet wall; render is applied too thin; masonry joints are recessed or raked out; the mortar used to bond the masonry is of a weak consistency or the mortar joints haven’t had enough time to cure after construction of the masonry.

No, as it will delay the curing time and compromise the chemical bond between the product and the substrate.  You may also see efflorescence staining on the blockwork.  If this is not removed completely from the substrate before the render is applied, the render will start to break down and delaminate.

There are a number of reasons cracks appear in external render.  The most common are the substrate has cracks, bed joint reinforcement has not been applied at every two courses, above and below, or window or door openings or substrates and infill blocks are different strengths, which leads to differential movement.  Bed joint reinforcement is a requirement of NHBC, LABC, Premier etc.

If the existing render substrate is well-bonded and there are no surface defects, delamination or cracks, then yes, new render can be applied over existing render.

Yes, our Mineral Render, External Wall Insulation (EWI) and Pointing Mortar training sessions are aimed at contractors, applicators and distributors who are looking to expand their knowledge or improve skills.  Further details can be found on our Sika Wishaw Training Centre web page.

For Applicators and Trade Professionals, Sika Parex render products are available to purchase through our nationwide distributor partners.

You can find details of a local stockist on our web page: Find a Sika Render Stockist.

Please visit our contact us page where you can view an area map displaying contact details for our local Business Development Managers and Specification Managers.  Contact details for our Technical Team can also be found on this page should you have any technical queries.