The thermal upgrading of solid wall structures and heritage buildings of historic importance presents a myriad of challenges, since over-cladding is seldom an option.
The only intelligent method of improving the thermal performance of the external walls of these buildings – largely constructed in lime mortar – is to insulate internally. However, the natural ‘breathability’ and through-wall performance must be fully evaluated with the following in mind:
Sand Cement Render has been used on period properties for many years, since inception in 1940’s. However, the suitability on buildings constructed of clay bricks and lime mortar is increasingly better understood. Key differences relate to levels of movement and breathability which results in premature cracking, delamination often resulting in damp problems within the property.
For more information please click here to visit the Period Property UK website
Removing Sand Cement Render and replacing with a traditional lime render system simply returns the building to its original design and function.
Common Problems
The first image image shows a stainless steel, clay coated lath. The other image shows why this is an unsuitable substrate with a timber lintel and some blown bricks.
Image above shows a timber lintel and blown bricks
Image above shows clay fused brick mesh. This is mechanically fixed with stainless steel screws to create a suitable substrate for lime render when overcoming unsuitable or excessively porous brickwork.
Traditional techniques and skills are still used for the application of lime render.
Note: there is no use of metal or plastic beads. Corners and reveals are formed with timber during levelling and scratch coating.
Image above shows traditional timber formed corners & reveals during levelling and scratch coats.
Image above shows window reveals formed with lime render coat applied before painting.
We supply & install heritage approved breathable render systems from Tellings Lime products.
These mortars ensure that period properties function as originally designed: allowing the structure to move as individual elements rather than as a mass. Lime render is fully breathable and provides a superb decorative finish for renovations and conversions, offers extremely high levels of flexibility and durability. Unilit hydraulic lime products conform to the European Standard ENV-4951, NHL 2-3.5 and 5.0 for natural hydraulic lime.
GPD contracts deploy traditional lime rendering methods and do not use modern plastic beads or metal beads. This provides significant benefits to the quality of finish and longevity of the system.
Click here for more information about Telling Lime.
