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When mortar deteriorates, so does its ability to repel moisture. As moisture infiltrates masonry, it begins to wear down the building’s stones and bricks, causing serious damage. Moisture leaks can cause mold and mildew to accumulate and building materials to rot, which often leads to the loosening and even loss of stones and bricks. Additional moisture will force masonry to expand and contract more than it normally would as temperatures fluctuate. As this occurs, masonry will be damaged.

The mortar joints of a building’s masonry contribute to its overall strength. When mortar wears away, the structure can be left in a weakened condition. The repointing process involves the removal of old mortar by either grinding or raking it out. After removal, the contractor will fill the joints with fresh mortar. Upon completion, the joints will regain their strength.

Ignoring masonry issues will cause them too worsen over time. Repointing at the onset of deterioration stops its progress, which prevents additional damage. If mortar is allowed to weaken for an extended period, it can compromise the structure of a residential, commercial, or historic building and may even cause the building to collapse. Preserve the integrity of your structure by monitoring its masonry and acting swiftly once you detect any issues.

Why should we continue to use lime in the late and early twenty-first centuries? As a construction mortar, from mass foundations to walls, arches and vaults, lime is resilient and flexible, adjusting to minor settlement and accommodating thermal movement. It is ideal for stuctural

repairs to lime built masonry buildings. For repairs and repointing of masonry work, lime mortar can be matched to the density of the brick to minimize the risks of salt damage. The porous nature of the material means that any minor cracks which do occur are less likely to admit water, and may even heal over a period of time by the slow action of dissolution and recrystallization of lime.

Why should I use lime?

Lime Mortars have certain characteristics which make them the most appropriate material for repairing buildings constructed with lime. Lime Mortars allow traditionally constructed (mass wall) buildings too ''breathe'' unlike modern Portland cement (OPC) mortars which can be virtually impermeable to moisture, trapping within the walls and leading to dampness.

How do I make sure I get lime pointing right first time?

The successful use of lime mortars relies heavily on the use of good quality, appropriate materials, and on adequate preparation of the wall surfaces. Curing of lime mortars is critical, and can be more onerous than that curing for cement mortars (depending on the time of year and local environment). This requires appropriate levels of wall protection following application of the mortar.

When is re-pointing required?

Re-pointing is necessary when existing mortars have weathered to reveal open or recessed joints, which are vulnerable to water penetration. Where existing, original mortar appears sound, it should be left undisturbed. Often, only patch pointing is required. It is recommended that you should have a sample of the original mortar analyses to reveal its constituents which can aid specification of a replacement mortar, and by identifying a 'matching' sand you may well be able to get a mortar of a similar appearance to the original.

Why shouldn't I use cement?

We think cement is a great material, it just shouldn't be used on masonry buildings! Cement is a brittle material that doesn't allow for the movement of old buildings and therefore is prone to cracking. It is non-permeable so while it's in a good condition it stops moisture from entering a structure, however once it's cracked moisture will get in through but cannot easily leave because the evaporation surface is far too small. Cement is bad for soft (high permeability) bricks; instead of the mortar joints handling the moisture, the brick  will, which leads to deterioration mainly through deposition of soluble salts which expand within the brick structure and also by freeze-thaw mechanisms. 

Can I do lime pointing myself, or should I employ a competent tradesperson?

We would normally advise that you employ a competent tradesperson with the appropriate experience – you should always ask for examples of previous work carried out, and satisfy yourself that they will carry out the work to your expectations. Sample panels should always be carried out for approval at the earliest date. However, we do offer a range of training courses suitable for those with minimal tool skills, and our consultants can advise on the appropriate materials and methods of repair, should you wish to carry out smaller scale works to your own property.

Should I remove any existing cement pointing?

In most cases, yes, as cement mortars can damage adjacent masonry and can cause moisture retention within the walls. However, there may be cases where removal will cause substantial damage to the adjacent masonry – careful judgement based on the success of small trial areas should determine whether or not removal is appropriate or not, and this must be carefully considered against any existing problems with the building or structure, caused by the presence of cement pointing.