Tiling on the Exterior cement Renders ?

Leave a Comment / By /

Tiling Onto cement Renders 

The rendering must work well with both the tile bedding method and the background to which it is applied. 

A rendering’s entire thickness shouldn’t be greater than 20 mm since doing so might lead to excessively high shrinkage stresses and subsequent cracking. Each layer of rendering must be at least 8 mm thick and no thicker than 16 mm. 

For at least the first three days after application and for at least two weeks before beginning the process of fastening tiles, the rendering has to be covered to avoid quick drying.

Under unfavorable weather, humidity, and site circumstances, this time frame should be prolonged (see BS 5385-4). 

NOTE In general, fine shrinkage cracks without deboning are acceptable. It is important to take precautions to prevent surfaces from drying out before rendering is applied after wetting them down to control suction (see 8.2.1). 

Before applying any bonding process, the renderer must keep up with the wetting or the surfaces must be rewetted as needed.

For work above the first floor and in any situation where differential movement is anticipated or the background material is deemed too weak or friable to support rendering and/or tiling without such treatment, such as concrete and concrete blocks containing lightweight aggregate (see 9.4), rendering through anchored reinforcement is advised.

If rendering is required in two coats, the first coat should be combed before hardening to serve as a key for the second coat.

Use the comb to make wavy, horizontal furrows that are 5 mm deep and have metal teeth that are typically spaced 20 mm apart. 

Before applying a second coat, the first coat needs time to set and dry out in order to allow for shrinkage. The second layer shouldn’t be as thick or have a richer mixture than the first coat.

The final layer should be gently combed if the tile bed will be made of cement and sand mortar; nevertheless, if an adhesive will be used, the surface should have a wood float finish.

Where the tile bed is an adhesive, the trueness of the rendering surface shall be such that any gap beneath the straightedge, between points of contact, does not exceed 3 mm when examined with a 2 m straightedge. Local adjustment of the rendering surface is required if the gap is more than 3 mm.

It is crucial that a render be provided with a thick enough layer to handle any variations from the background’s real colour. Avoid using unreinforced and reinforced render in excess thicknesses (see 

Rendering through anchored reinforcement

The backdrop should be tightly fastened to the wire mesh. To guarantee that the rendering and the applied cladding tiling stay intact and are fully supported in the event that the adhesion between the rendering and the backdrop fails, the rendering should be done such that the mesh is totally embedded.
The backdrop shall be fastened with austenitic stainless steel welded-fabric reinforcing mesh that complies with BS 4483 and is made up of squares of 50 mm 50 mm with wires at least 2.5 mm in diameter.
 According to the strength of the backdrop, it is imperative that the fixes into the structural wall be made at least 40 mm deep, going through any dubbing or the first coat of rendering, as specified in this clause.
The British Standards Institution published BS 5385-2:2015 British Standard 20 in 2015.Apply the reinforcement with the horizontal wires facing outward, and secure it with 50 mm 10 mm austenitic stainless steel anchors or by drilling holes in plastic anchors for stainless steel screws with countersunk heads. 
Use screws that are tapered, not parallel-sided, and that are at least 38 mm 10 mm gauge and comply with BS 1210. Although 40 mm can be utilised in thick, robust backgrounds, plastic anchors should be around 50 mm long.
 Fixtures should be positioned such that the horizontal wires rest on the screws and provide direct support for the mesh at intervals of about 450 mm in both directions. As the screws are installed, plastic or stainless steel washers should be positioned to space the mesh’s vertical wires at a distance of about 4 mm from the surrounding material.
At all intersections, including exterior angles, mesh sheets should overlap by around 100 mm. They should either be held firmly against the spacers by placing stainless steel washers on the inner and outer faces under the heads of the fixing screws or bolts, or they should be fastened to the fixings using austenitic stainless steel binding wire that is 1.22 mm in diameter, tightly twisted, and with its ends turned inward.
While the background and mesh are still wet, a slurry coat of neat cement should be brushed on them. The rendering should then be applied, working around and through the wires and making sure that it is in full contact with the background and that the mesh is covered by a thickness of about 7 mm.
Spatterdash, which may be used in place of slurry, should be a mixture of 1:2 cement and sand by volume, applied to the backdrop with a mechanical device or a dashing scoop to a thickness of about 3 mm on average, and then allowed to slowly dry to cure before rendering is applied.
When applying dubbing or a first coat of rendering in thicknesses greater than 20 mm to bring the background to the desired plane, a slurry coat or spatterdash should be used first. 
Then, the dubbing or rendering should be applied in single coats that are each 8 mm to 13 mm in thickness, combed, and then cured as described in 9.3 before the reinforcing mesh is fixed.
 Before the mesh is set and additional rendering is performed, a total thickness of 25 mm of dubbing or rendering is not recommended.

 

About Tiles Adhesive :- 

  • Always use Type 3/type4/type5 adhesive for the exterior tile and stone installations as per the IS 15477 Standards 
  • During the adhesive’s open period, just spread it over the area that can be tiled.
  • Use an appropriate square notch trowel to comb the glue to the necessary depth.
  • Make sure that each tile is in excellent contact with the back by applying strong pressure while lightly twisting the tiles into place. Leave no space between any tiles.
  • Depending on the porosity of the surface and the ambient circumstances, tiles should be attached within 20 minutes of adhesive application. After fastening, tiles can be changed for up to 15 to 20 minutes. Touch the adhesive ribs from time to time, and if a skin forms, remove the glue and reapply.
  • Unless self-spacing tiles are utilised, provide appropriate joints between each wall and floor tile. 

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top
%d bloggers like this: