Cement based mortars might not be a good idea for a number of reasons and that is view it is always advisable to perform lime mortar pointing. This is because you will get a quite a softer material which is more porous so that moisture in the joints can easily be evaporated as compared to the setting where stone or brick is used.
This means you can reach lower moisture levels pretty quickly and thus you can automatically get rid of soluble salts that usually build up because of presence of moisture that leads to damaging the wall and reduce the longevity of the structure.
Below is a comprehensive guide to all the steps required in performing lime mortar pointing.
Preparation
Rake out if there is any defective pointing already present and its depth should be as much as two time the joint’s width. However, make sure that is doesn’t remain less than 20 millimeters. Also ensure to keep the joint’s back as square in shape as possible.
Damping
Once you have gotten rid of dust or loose materials, dampen the joints. Leave sufficient time for the brick or the stone to dry out so that maximum compaction can be reached in the joint.
Premixing
Premixing does wonder to lime mortars. You can do this a couple of weeks before you perform the task and then again knock it up when you are about to do the job. This will help reduce the mortar shrinkage. Pre mixed lime mortars are also available to save you time.
Gauging
It is always suggested to use a lime mortar, which is premixed for external as well as internal applications of lime pointing. However, if you are using NHL mortar, the extent of exposure would eventually help in the appropriate strength of the structure.
Pointing
You should always start from the top of the all. To force in the mortar, you should be using a suitable pointing spatula. If your joints are not lesser than 20 millimeters but are even deeper than that, then you will be required to dubbing before the process so that shrinkage doesn’t occur.
Brushing
A churn brush should be used to tamp the joints. The exact time to do this is when your lime pointing has reached green hard. When you brush, you will be getting rid of lime patina on the mortar surface.
Protection
All new lime pointing must be protected with a hessian cloth. This helps from direct sunlight in hot weather as well as from rains and windy weather.
When to Apply?
The time of the years is very crucial when it comes to applying lime mortar pointing. According to its characteristics, it shouldn’t be applied towards the ends of the year and neither should it be applied in the beginning of spring. If it is applied during these times, it may be put at risk of frost damage since frost crystals prevention is an important aspect in the process.
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