Browse Forums Building A New House 1 Aug 10, 2020 5:46 pm Hi, I am looking for some experience here around facade render finish (not acrylic) over brickwork. I have been told that render needs maintenance and probably lasts 5-10 years before it needs a fresh coat of paint, but my question is around the quality of the finish in particular hairline cracks on the street facing facia but significantly less on the inside sections. Appreciate all constructive help. Thanks in advance. Re: How long should Render last before cracks (not settlemen 3Aug 11, 2020 8:09 am Sand/cement render, if applied properly will last a long time without any maintenance at all. Paint helps seal it of course and stops the action of wind, rain and the sun breaking it down. Some causes of hairline cracking are not wetting the walls enough before the render is applied, weak render as in too much water or sand in the mix and not enough cement and drying too fast. Any of these will lead to hairline cracks and are regarded as of a minor problem. Our old double brick house was built just after the war and has quite a few hairline cracks but no major structural ones. The internal walls haven't been re-painted for the last fifteen years and still look pretty good. An older renderer I know who used to do fantastic work used to send around one of his labourers after he had done a house and get him to wet the walls down with a hose in hot weather as he said the render needs to dry slowly. Before he rendered the walls as well he used to hose them down to also help slow the drying process. What direction does your facade face? If it is North, NW or NE, I'd say the wall has dried out too quickly being exposed to the sun. " to eliminate hairline cracking I would ask renderer to use expanded metal " Pfft, maybe over cracked brickwork... Stewie Re: How long should Render last before cracks (not settlemen 4Aug 25, 2020 2:24 pm Stewie D Sand/cement render, if applied properly will last a long time without any maintenance at all. Paint helps seal it of course and stops the action of wind, rain and the sun breaking it down. Some causes of hairline cracking are not wetting the walls enough before the render is applied, weak render as in too much water or sand in the mix and not enough cement and drying too fast. Any of these will lead to hairline cracks and are regarded as of a minor problem. Our old double brick house was built just after the war and has quite a few hairline cracks but no major structural ones. The internal walls haven't been re-painted for the last fifteen years and still look pretty good. An older renderer I know who used to do fantastic work used to send around one of his labourers after he had done a house and get him to wet the walls down with a hose in hot weather as he said the render needs to dry slowly. Before he rendered the walls as well he used to hose them down to also help slow the drying process. What direction does your facade face? If it is North, NW or NE, I'd say the wall has dried out too quickly being exposed to the sun. " to eliminate hairline cracking I would ask renderer to use expanded metal " Pfft, maybe over cracked brickwork... Stewie Hi Stewie, Sorry i missed the replies here. The house faces west. Whilst i appreciate settlement cracks, the render has obvious spidering cracks so much that virtually everyone notices it as the come to out new home. Im guessing that they all see these cracks. Im working on the builder but the "within tollerance" is a regular comment back. And it only is a problem when it can fit a credit cards in it. Re: How long should Render last before cracks (not settlemen 9Aug 25, 2020 8:29 pm Mirrmu83 Silicate is European for sand More like quartz. I am talking about something similar to this: https://rsistore.co.uk/product/ewi-040-silicone-silicate-render-25kg/ Re: How long should Render last before cracks (not settlemen 11Aug 25, 2020 8:49 pm There are different types of sand (e.g. calcium carbonate, aragonite/coral, etc.). But yes, silicon-silicate renders are finishing (or decorative) renders. The base render can be standard sand cement render. Re: How long should Render last before cracks (not settlemen 12Oct 01, 2020 7:17 am I am lead to believe thqat the cheapest option for the original renderer is to apply a primer and then Rockcote over the top. Apparently that will be less than stripping existing concrete render, and reapplying and painting again. That may also mean that the render may avoid the cost of a weeks hire of scaffold too. Does that all sound likely? Re: How long should Render last before cracks (not settlemen 13Oct 01, 2020 10:16 am Where is the cracking, is it everywhere (crazy cracking)? near windows/sills? at damp proof course? middle of a wall? I assume when you mention Rockcote it is a tinted trowel-on texture coat. This type of product is not a flexible coating. They comprise around 70% solids and are acrylic based. Crack bridging ability is low. They require painting over to have a warranty. A membrane provides more crack bridging, Rockcote would have a product line or there is Dulux Acrashield. Very heavy paint. If your walls are already painted you shouldn't need a primer, just a clean with hose and mild soapy water. Do you have a scope of works? If have texture on wall now, the patch will show through The standard for repair of texture is to patch, re-texture corner to corner,… 5 6922 The mesh is often stuck on wall first then rendered over, which means it does nothing Not to specifications Get a scope of works in writing before start, needs to be… 10 9036 I am in the same situation, would you be able to give some insights in to this? I am in SA 8 17063 |