Repointing in lime mortar

Historic buildings have to be maintained with the correct materials, matched to the original and suitable for the often delicate masonry.

This tall Victorian townhouse in the Oxton conservation area, Wirral, had little or no maintenance over the past few decade’s and weather had eroded the lime mortar on the exposed sides of the building.

Our task was the removal of a disused and severely dilapidated chimney stack, repairs to enriched soffit and internal guttering within and the repointing of the weather damaged brickwork using a hot mixed lime mortar containing local sharp sand and crushed stone dust

The chimney stack had been repaired badly following severe storm damage and beneath the cement pointing the original lime mortar was now just dust and dirt.

Using cement on this type of building causes irreversible damage as cement will trap moisture that would normally dry out through the lime mortar joints.

The spalling and failure of the soft bricks is due directly to the blocking of the joints with cement. Moisture is forced into the soft brick and salts and freeze thaw conditions often lead to the total loss of masonry.

Weather had caused large, deep holes in the existing mortar allowing water into the building, some bricks were completely loose. minor, incorrect cement repairs had been carried out but caused further deterioration and were removed

Exposed mortar joints allowing moisture ingress and causing damp patches internally

The repointing was carried out using hot lime mortar as a binder and following analysis we sourced a coarse, local sharp grit sand and crushed yellow sandstone dust.

For repointing projects we often mix our lime mortars using a hot mixed method, a drier and stiffer mix is obtained by storing and reusing the mixed mortar after it has cooled down, often a day or two later.

The material is pushed deep into the pre wet joints using traditional pointing irons and finished with a flush, open finish

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