Lime and Earth bonded constructions have the need to breathe factor and need adequate protection from the elements this would be a good hat, a coat that withstands water but breathes, and shoes that are not constantly wet.
Yes Historic Buildings are like people and should be not mis understood for a good healthy clean aired dry environment, if misunderstood could have catastrophic events for anyone with their lifetime investments and their own health .So how and do you initially assess the state of your buildings? Strange smells, damp spots insect manifestation.
The key is a Good Roof & Drainage that releases water away from the property and Ventilation Windows. Vents, air bricks and building fabric that breathes to release the moisture from inside the property, and that will withstand the elements with its coatings, whether that being pointed, brick or stonework, or rendered facades. Living and Working in the North West you are up against the elements and challenged everyday so that Stone or Brick built house needs looking after.
So check your roof first. Is it leaking through ridge/ roof tiles or Flashings stone slate or lead, Coping stones are a huge factor on a façade that are often overlooked, that should be water tight and have a minimum of 45mm overhang over the finished work, to provide adequate protection. Gutters down pipes and drains, are they clean and free flowing? Ground levels externally should not bridge the damp course or inner floor, or this could lead to rotten rafters and potentially DRY ROT
Stone and brick buildings breathe 85% through the joints/pointing, if one of these factors are misunderstood, breakdown of building fabric will occur and Damp, Insects Mould will appear creating an unhealthy cold living environment.
Financially all that could lead to waste of fuels trying to heat the house as the insulation value of building materials drops drastically when Damp ,and disease Bronchitis /Pleurisy/arthritis does quite often appear .Acid rain (Sulphur Dioxide SO2) is a serious opportunity to learn for all and is having a major impact on stone houses that have been pointed or rendered with cement based Mortars .
Stone houses have to contend with at least 15 ltrs a day of ground moisture as well as 1 ltr for day for every person inside this accumulates to around 5.5 cubic tonne per year of ground moisture that is coming up through the floor into the masonry that cannot breathe through the joints, so the wall becomes slowly saturated
Acid rain Sulphur Dioxide SO2 mixes with Exhaust fumes and Co2s and becomes Calcium Dioxide that then reacts with the binder in the stone that is most of the time soft sand stone Lime CaCo3 that turns into Gypsum Yes Plaster CaSo4 that is visible on most surfaces affected .
The crystals grow then rot turning black in the process leading to the destruction of the stone known as Spalling. There goes your lifetime investment. Remove all cement render and pointing that will release the insects and moisture this will take time as masonry dries at a rate of 1mm per month. Choosing the right materials to repair or replace and that should be NO harder than the brick or stones this will allow for any potential movement over the year as the house contracts and expands.
If its built with Lime CaCo3 then fix it with Lime but keep in mind the exposure of the wall and hardening times as Air & Hydraulic Limes need drying\Carbonating Lime will need to have cured 5mm to survive any kind of frost and takes 1mm per month to carbonate so try to put on early as possible in the year. The picture is of the Lime cycle
Additional protection is needed for a Lime Mortar renders once applied Hessian against rain or frost or when cured, be that in the form of a mineral paint or a lime wash Hot or cold this is to prevent the grains of sand being washed out on those Rainy days .
Bricks when becoming saturated in the winter months will freeze and the faces of the bricks will Blow in some cases where the damage is so far the bricks will need replacing, all because of the cement pointing and bridging of the damp proof membrane, this is known as Freeze Thaw . This Blog will be updated with current findings on buildings and my method of repair that are always open for a Debate or discussion
Thanks for taking the time to read kind regards Karl Claydon