Our surveyor has a wealth of experience of listed buildings, and traditional buildings that sometimes need a sympathetic approach using lime to help resolve damp issues.
Traditional and listed buildings especially timber framed buildings that are suffering with damp need to be surveyed by a competent qualified surveyor. The surveyor should have a good understanding of how these buildings are built, this gives the advantage of knowing where to look, and what to look for, and what sympathetic repairs are needed to preserve the long term future of the building.
We have the best technology available to aid all of our surveys to include the Flir T600 thermal imaging camera thats meter linked to a thermal hygrometer (MR77), which allows us to scan a building rapidly for defects. We have aerial cameras, and also carry out aerial thermal imaging on our 10m pole.
We also have a range of damp meters, drain cameras, borescopes, sub floor ventilation cameras, a radio controlled buggy with a camera for sub floor inspections, remote void monitoring for drying down of timbers, data logging equipment, and real time data logging equipment.
We also have our own laboratory where we use gravimetric-oven dry analysis to BRE Digest 245, this gives us quantitative results on how much free moisture is present in a sample of mortar and how much hygroscopic salt is present. It is very important to know exactly what is causing suspected rising damp, especially on ancient heritage plasters before any expensive remedial repairs are carried out. BRE Digest 245 is the only way to test for rising dampness, a damp meter can only be used only as a guide.
Some of the repairs that have been carried out to listed buildings have been using modern methods that are not sympathetic with how they were originally constructed. Take hard cement pointing for an example, hard cement pointing on a timber frame is the kiss of death, the cement traps the moisture against the timbers and decay starts, with the decay comes beetle infestation (woodworm) which is normally deathwatch beetle (Xestobium Rufovilosum).
The below picture is an example of Deathwatch Beetle on a timber framed building in Wiltshire that was covered in sand and cement.
External cement rendering that has deteriorated and cracked allows penetrating dampness to enter the building fabric. Once this happens timbers are at risk of fungal decay and woodworm infestation. South facing elevations are more prone to thermal movement, and are more likely to crack, lime render is more flexible and is less likely to crack and will move with the building as it heats up and cools down.
Internal lime plastering
Lime plastering internally is carried out with a scat coat, or harled coat, a haired coat to give it strength, a float coat to flatten the wall, which is then finished with a lime putty finish plastering coat. Lath and plaster ceilings can replaced or repaired as necessary if they have dropped or are suffering from decay or infestation.
Lime pointing
The job of the lime mortar pointing is when the wall gets damp the moisture evaporates out of the lime mortar bed.
This is sacrificial to the stone or brick, this means that over the years it weathers and when it needs to be replaced it is on a like for like basis.
Hard cement pointing traps the moisture, in winter the water freezes and expands which then can cause spalling of bricks and stone over a long period of time. We now have a bigger problem, because not only does the cement pointing need replacing so does the stone or bricks which can be very costly.
Most modern plastic masonry paints can trap moisture in the wall and cause damp and timber decay issues.
The problem we have is when the building moves through the seasons and thermal expansion, cracks appear which might only be very small, however come winter when we have wind driven rain this moisture now enters the building fabric and is trapped behind the plastic paint. The wall is then suffering from penetrating damp through the winter months, and then spring comes and a decorator scrapes the cracks, fills and re-paints with another plastic paint.
This wall would most definitely have not dried down, this is why the paint continues to bubble and cracks again when the building moves again through the seasons and thermal expansion.
Ideally plastic paints should be removed and allow evaporation from the sun and wind, this is how a building naturally dries down.
Modern masonry paint removal can be a difficult job without the right equipment. We actually own our very own Thermatech Super heated hot water system that is capable of delivering temperatures up to 150˚C, which warms the paint so it can be stripped off easily. Where some of the paints are more stubborn we also use a Thermatech abrasive attachment along with a light abrasive. This basically creates a pressurised mixture of hot water and abrasive medium.
Trained and competent technicians proudly showing off our training certificates related to the use of the Thermatech masonry cleaning equipment.
Modern masonry plastic paint removal
The below project shows a building that was suffering from rising and penetrating damp issues. There were issues with dry rot on some bearing end timbers also, because of long term penetrating damp. The external masonry paint was cracked in places and generally in poor condition where previous coats hadn’t bonded to other coats.The pointing beneath the paint was a hard modern sand and cement, and the lime mortar pointing was damaged because of the constant damp, and freeze thaw cycle. As you can see the transformation of the property made the building really stand out. This added value to the property, and also kept us busy with additional works in the area because of the recommendations.
If the building is to be repainted we would recommend a traditional lime wash or Kiem mineral based paints www.kiempaints.co.uk
Lowering ground levels is a simple yet effective way of reducing rising damp. This allows greater evaporation at low level which is essential on controlling the height of rise. Ideally external levels are lowered 150mm below the damp proof course or internal floor level. Mass ground excavation is rarely necessary and also neither are French drains for basic rising damp issues where there is a very low capillary moisture content. Most of the French drains I have looked at, have actually caused more issues thats why many people call them a French moat.
Complete Preservation can offer you an initial survey, right through to the completion of any lime and sympathetic damp repairs as needed.
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