Lime Ash Floors

Lime ash floors were made with the ash residue of lime kilns. They were usually laid over a bed of reeds laid on wooden laths fixed to the joists. They were a clever composition as they are flexible enough to cope with minor movement in the building, they are breathable, they are much warmer to walk on than a concrete floor, and they look good.

If you are fortunate enough to still have lime ash floors in your house it is likely that at some time they will need repair. Damage can occur for a number of reasons:

  • Failure of the laths due to water or insect damage.
  • An inadequate previous repair.
  • Breaking caused by structural changes such as removing a wall.
  • Lack of care in making holes for plumbing or electrical supply.
  • Cracking caused by significant movement of the house or simply through wear and tear.

Lime is now generally produced on a factory scale and the original raw material for making lime ash floors is not available. Therefore there is no such thing as a ready-made repair mix.

The floor above had failed due to insect damage to most of the laths. New riven oak laths were used as replacements. Fortunately the old cracked lime ash was kept and this was recycled into the repair mix.

This floor had been previously repaired and although the repair mix was good the laths had been set too high resulting in the new lime ash section being too thin. The repair area cracked over the succeeding years.

Battens have been fixed to the sides of the joists allowing the laths to be set lower and so making the repair section of floor thicker.

The new repair mix has just been laid and is awaiting a final finish with a trowel.

This photo shows a limecrete floor from below. The floor mix can be seen keyed into the laths