Ask a tradesperson
Plastering
Do i really need lime-based external render?
Hi Builders & Render Professionals,
I live in a three story Victorian property in the South East that's been converted into 3 flats. All 3 flats own a share of the freehold. We have some minor cracks in our front render and it needs repairing/ decorating.
I've obtained some quotes ranging from £4-6K to repair cracks, re-render (where necessary) and redecorate.
HOWEVER, some of my fellow freeholders are 'eco warriors' and are insisting that the render has to be eco breathable materials, notably NHL 3 lime-based render. This type of render is substantially more expensive.
不知道很多关于渲染(或贴),我really like to hear some professional opinions on this. I've been presented with the 'we don't want to throw good money after bad' argument and that standard render won't give the structure of our property flexibility to breathe. However, out of all the companies that quoted, not one suggested lime-based materials - That indicates to me it can't be all that bad…
I'd really appreciate it if you could share your opinion on this. Is lime-based render really the way to go or is it just something best kept for 'Grand Designs'?
Many thanks and I look forward to hearing from you.
Mark
3 Answers from MyBuilder Plasterers
Best Answer
if the property is of solid brick construction, i.e. no cavity, it will have been built using lime mortar, as your neighbours state this allows the building to breathe, stopping water ingress into the property through the walls, the worst things you can do to a solid brick building is paint it,render it,or re-point it with a cement based product as these will stop the building breathing and create internal dampness trapping any water ingress behind the render/pointing, most modern tradesmen do not understand older building or how the materials used in their construction work to-gether to stop water ingress into the property, even less of them are able to use lime mortars ,renders ,plasters.
these materials are still available although a lot more expensive.
THEIR IS NO CEMENT IN LIME RENDER,PLASTER,MORTAR, or additives anyone who tells you different run a mile from, it is hydraulic lime NOT hydrated which can be bought at most builders merchants,
most modern tradesmen can quite happily render but not with lime render which is a totally different animal,
It is now getting to the point in the year where it will become to cold to apply lime render successfully this year unlike cement it takes 96hrs to become fully weather proof and a further 3mts to go of fully.
your best bet is look for someone who specialises in the maintenance and repair of older properties.
having just finished a project in Boston on a grade 11 listed building, removal of the cement render on the wall at the end of the extension and replacing it with a lime render has stopped dampness in the wall in the room next to this over 5mtrs away from the offending render.
good luck Alex
Answered 16th Oct 2014
It does need to be rendered with a lime based render. The reason none of the plasterers have raised it is because of a lack of knowledge regarding older properties.
It is not the time of year to be rendering now, I am just finishing my lime work for the year as we head in to winter. Contrary to the above comment at this time of year lime takes around 28 days to develop a moderate frost resistance and from November onwards around 56 days.
Answered 17th Oct 2014
Regarding the use of NHL3.5 lime, there is a school of thought that this is too hard for older properties and that NHL2 is a better bet.
Answered 3rd Jan 2021
