Truth be told we don’t see a lot of it (lime render) in Portugal.
We do see a lot of old lime render that has partly washed off homes but we very rarely see any new lime render in Portugal or lime mortar being applied in Portugal.
It is made just like a normal modern cement render mortar and is composed of lime and an aggregate such as sand, mixed with water.
Cement render also is made with lime and an aggregate such as sand, cement and mixed with water.
So when people talk about Lime Render they actually are talking about a normal render without the addition of cement. The lime is not a fruit juice it is slaked lime. The slaking of lime is very dangerous and should be tackled with extreme care or you could be badly burned and blinded.
Slaking is the soaking of the powdered lime in water for up to a week. I have witnessed many accidents in the past when lime was slaked on site. As it ferments it builds up gas bubbles which explode with some force spraying large amounts of the lime over people working with it or in the vicinity.
The soft, porous properties of lime mortar provide certain advantages when working with softer building materials such as natural stone and terracotta because the render will break before the terracotta or soft stone.
Usually any dampness in the wall will cause the lime mortar to change colour, indicating the presence of moisture. The effect will create an often mottled appearance of a lime washed wall. As the moisture levels within a wall alter, so will the shade of a lime wash. The darker the shade of lime wash, the more pronounced this effect will become.
This is not a photograph or lime render “Breathing” it is showing that the stone wall behind the render is saturated with water.
You have probably heard that Lime Mortar is available in many mixes.
For instance 1:1:6 is a satisfactory mortar mix for various purposes, but behaves like cement-based mortar.
1:2:9 has been found to be prone to premature failure.
What about 3:1 + 5% or 1:1:6 and 1:1:4 There is a lot to understand before you ask a builder to build or render in “Lime Mortar”
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