I would appreciate advice on roughcast rendering. Roughcast render redone on Scottish property where 5/8 inch gravel was supposed to have been used. The original contractor subcontracted work on the project including rendering and external painting. The exterior now needs repainting and two different painters, who are quoting for job, have complained about the poor quality of the render - quite a few gaps where stone has fallen off and paint just put on top of gaps - and the size of the stone used. One painter says the stones are nearly two inches in places. Is there a standard size for roughcast stone or is it personal taste?
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Roughcast Rendering
- Thread starter jmadden
- Start date
biffvernon
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- Lincolnshire
What is the binder? Ordinary Portland cement or lime?
Hi Biff
I don't know. My mother was asked to pay for a long list of items including plastering sand, washed 5/8" round gravel, something called SBR, cemtone mortar mix, unibond waterproof PVA, scrim cloth, carlite bonding, bags of lime and cemtone integral waterproofer.
Thanks
Jennifer
I don't know. My mother was asked to pay for a long list of items including plastering sand, washed 5/8" round gravel, something called SBR, cemtone mortar mix, unibond waterproof PVA, scrim cloth, carlite bonding, bags of lime and cemtone integral waterproofer.
Thanks
Jennifer
biffvernon
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- Lincolnshire
There are two very different approaches and they require different materials and methods. One is to stop water ever getting into the building, the other is to ensure that water can get out of the building
The latter is the preferred method for caring for an old building. The aim is to keep the walls 'breathable' or having a high water vapour permeability. This is how buildings before 1900 were intended to function. In this case the house would be rendered with lime and an aggregate of coarse sand, though two inch pebbles is rather on the giant size, and perhaps painted with limewash. Water vapour can readily pass through this, helping to keep the inside of the building dry.
Modern buildings are more likely to be rendered with cement. This is far less breathable and may be sealed further by 'waterproof' treatments and modern paints.
If you have an old building that has been mistreated with such modern materials the choice is either to put up with it and repair with similar materials or take it all off and start again with traditional materials and methods.
From your shopping list it looks as though modern, waterproof materials are going to be used. If yours is an old building this is either completely the wrong approach or making the best of a bad job because it would be too difficult and expensive to do it properly.
The latter is the preferred method for caring for an old building. The aim is to keep the walls 'breathable' or having a high water vapour permeability. This is how buildings before 1900 were intended to function. In this case the house would be rendered with lime and an aggregate of coarse sand, though two inch pebbles is rather on the giant size, and perhaps painted with limewash. Water vapour can readily pass through this, helping to keep the inside of the building dry.
Modern buildings are more likely to be rendered with cement. This is far less breathable and may be sealed further by 'waterproof' treatments and modern paints.
If you have an old building that has been mistreated with such modern materials the choice is either to put up with it and repair with similar materials or take it all off and start again with traditional materials and methods.
From your shopping list it looks as though modern, waterproof materials are going to be used. If yours is an old building this is either completely the wrong approach or making the best of a bad job because it would be too difficult and expensive to do it properly.
Hi Biff
The property isn't old but did need rerendering which probably explains the materials used. However the 5/8" rounded stone ordered and paid for for the roughcast doesn't seem to have been used or perhaps it has and they ran out and just used the stones from the drive. The drive gravel mixture is remarkably similar in shape and size to what is on the render. Would it be a nightmare and expensive to strip off and redo? Now my mother is aware of the decorators comments she's fretting that the exterior is not as it should be. I am trying to attach a couple of images. Don't know if I'm doing it correctly.
The property isn't old but did need rerendering which probably explains the materials used. However the 5/8" rounded stone ordered and paid for for the roughcast doesn't seem to have been used or perhaps it has and they ran out and just used the stones from the drive. The drive gravel mixture is remarkably similar in shape and size to what is on the render. Would it be a nightmare and expensive to strip off and redo? Now my mother is aware of the decorators comments she's fretting that the exterior is not as it should be. I am trying to attach a couple of images. Don't know if I'm doing it correctly.
biffvernon
Member
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- 4,607
- Location
- Lincolnshire
You need to have the picture hosted somewhere else on the Internat and then copy the URL between the tags.