wall repair patch

a hole in the wallIf a wall repair patch of rendering becomes loose and falls away, or a blister of loose rendering develops, repair it immediately, because the rendering is usually part of the weatherproofing of your home. With a bolster chisel and hammer, hack away the loose, crumbling material back to the brickwork. Begin in the centre of the blister and work outwards towards the edges, until you come to sound material. Similarly, with a bare patch, hack away all round the edge of the hole until you reach sound rendering. Make your own mortar for the repair 1 part of cement to 5 or 6 of sharp sand with a proprietary plasticizer added is a suitable mix or buy a bag of ready-mix and add water. In either case the mortar should be of a stiff consistency. First, treat the bare bricks with a pva building adhesive, mixed and used according to the manufacturer’s instructions. Apply the mortar in two stages. Place some on a hawk, hold it close to the wall and push the mortar into the damaged area with a steel float. Just before this first application hardens, scratch its surface in a criss-cross pattern with a knife or the point of a trowel – builders call it the‘scratch coat’. Leave for 24 hours, then apply the finishing coat, making it as similar as possible to the finish of the rest of the wall. For instance, if the wall is smooth, spread out the top coat until it  is slightly higher than the surrounding area. Then draw a batten across the surface of the patch in a sawing motion to remove surplus mortar. Leave it for about an hour to dry, then dampen it with water – you can apply this with an old paint brush – and smooth it off with the steel float.

The other finishes you can achieve, which are listed below, should be worked while the finishing coat is still soft, a few hours after it has been applied. Roughcast has a proportion of coarse aggregate in the final coat, which is thrown (literally) on to the wall as a wet mix, and left untrowelled. Scraped finish is achieved by leaving the final coat to harden for several hours, then scraping it with a tool, such as an old saw blade. Textured finish has the final coat worked with a trowel or even an old banister brush. Stippled effect, too, is created with a soft banister or dustpan brush. Wavy effect is produced with a piece of ribbed rubber when wall repair patch. Bold texture is achieved by dabbing with a fabric pad.

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