Specialist traditional Lime putty repointing - Oxfordshire.
Lime putty makes a similar mortar to natural hydraulic lime in that it's porous and flexible. In some cases it creates a much lighter mortar. I have clients and architects who specify it because they feel it more appropriate. However, it cannot be used during the cooler months or on properties with a high moisture content.
Below: The Old Bakery at Shrivenham before refurbishment work began.
After: 1 x lime putty, 2x Ginger Wilkes and 1 x 50/50
Before: Buckland cottage.
If you'd like to see how this work was done then please view it on YouTube:
Lime putty (commonly referred to as non-hydraulic lime or fat lime) is a product used exclusively on older properties. It is the mortar which was originally used in period property construction and its origin can be traced back as far as construction in Roman and Egyptian times.
It is believed by many to be slightly softer and more vapour permeable than Natural Hydraulic lime (NHL) and also less cementitious. However, there is little evidence to suggest that this is true. It makes a lighter colour mortar which won't cure unless exposed to air. Although ideal for restoring historic buildings - it cannot be used during the winter months and should only be used when temperatures are 10 degrees or above. It also requires a different skill level than natural hydraulic lime and can be a more time consuming product to employ.
Before (Pury End, Northamptonshire).
When you know the right tools, procedures and mortars there's no telling what can be achieved.
For further information on this, please go to:
When specifying putty it's worth considering it as an alternative to NHL as it can be ordered as pre-mixed putty mortar. The benefit of its use are as follows.
- It can be stored indefinitely
- There is no need to inconvenience neighbours with noise, dust and dirt from a mixer
- There is no need for piles of sand to sit around on site
- If space is tight then containerised mortar can be stacked and used when required
- It can be used indoors without the need for potentially damaging wheelbarrow traffic
- It can cut down the hassle factor because it can be supplied already mixed.
Please see the photos below for examples of what this looks like when mixed with a good sand.
Close up view:
Some argue that when making the choice between lime putty and natural hydraulic lime it is best to have an expert eye assess the property to ascertain whether it was originally built with lime putty. If so, then you may wish to continue its use. However, NHL 3.5 makes an equally good mortar.
I would however suggest that the choice of contractor should be limited to one who is adept at working with putty as those who are less experienced may be reluctant use it.
Hockmore Cottage, Cowley, before:
When to use putty:
- Non-hydraulic lime is compatible with weak and weathered stone
- If your building is old and is prone to movement because it sits on insubstantial foundations then lime putty is ideal because it is argued to be the most flexible mortar and many believe it copes better with settlement
- When it is important that mortar and not the stonework becomes the sacrificial element in the building.
When not to use lime putty:
- When the building is very damp. Putty requires a dry environment to cure. Damp buildings prevent this therefore NHL should be used as this will set in the presence of moisture.
- Very exposed areas and chimneys.
- During the winter months
- When curing times are a priority.
If you'd like to know more then please go to http://mike-teacherlife.blogspot.co.uk/2016/05/the-use-of-lime-putty.html
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