"Thankyou for taking so much care"

I love taking care of old buildings. This one has been standing for 500 years and contributing to it remaining so, makes me a happy man. Water ingress and retention is one of the main causes of decay in traditional buildings, so keeping on top of leaks is of vital importance, and having breathable coverings allows them to dry out, if they do spring a leak.

Enter quicklime. Mortar made from sand slaking quicklime, is the best thing for rendering traditional stone built buildings. What we are doing here is moving in that direction, for this building; as the sliding sashes are renovated, they are being re-sealed with oakum and slaked quicklime.

Slaking the quicklime.

Soaking oakum in the still-slaking quicklime (after the reaction has cooled some; much heat is given off when slaking quicklime).

Sealing around frame with mortar made from sharp sand and the hot lime putty. This is not sand slaking (which is addition of quicklime to damp sand, a dryish process, where more water is added later to beat up a workable mortar). I have done it this way because I wanted three products from the same mix; oakum/quicklime 'filler', hot lime putty mortar to point the oakum, and thick limewash to coat.

Quicklime mortar (and the oakum filler) will give a much more breathable seal around the windows. The wood will last longer and the masonry which was built with clay/lime mortar, will be able to dry out if it does get wet. The cast iron gutter, hopper and downpipe have been re-jigged, so they all meet up, and dispatch rainwater away from the building (instead of into the wall, which was happening).

The new massive sweet chestnut sill, from Zav at Dart Valley Sawmills, will be shedding rainwater off this window, for many years to come.

The implication of using quicklime, is that it takes a long time to set. It is not hydraulic, i.e. it does not set by the addition of water. It sets by 'carbonation', the re-absorption of the carbon dioxide, that it released in it's making. It is effectively re-becoming the limestone, from whence it came.It needs to be protected with dampened hessian while this process takes place, so that it does not dry out too quickly. It's worth noting that modern portland cement, does not do this 'carbonation', it does not re-absorb the C02 that it releases, which means it is responsible for 8% of greenhouse gases released into the atmosphere, it releases CO2, but never re-absorbs, because it sets HARD. It's not breathable and causes moisture from leaks etc to stay in the building fabric. It's a no-brainer. Using quicklime (air lime) and caring for old buildings in this way, is caring for the planet. It's exciting, why do anything else?

The chemical explanation of this.

The practical side of this; covering with damp hessian, and keeping the oakum/mortar/limewash misted for at least a few weeks afterwards.

The bottoms of the boxes and cheeks have been repaired, with new timber spliced in. The sashes have been to the window hospital, and have been re-installed also. The above box sash, and the below horizontal sliding sash, with another piece of the lovely reclaimed greenheart, for replacement sill.

Putty all tidied and paintwork re-freshed.

"Thankyou for taking so much care".