Pilot Scheme for external refurbishment in local authority housing applications. The properties were poorly insulated and the external render dash coatings had become extremely friable. Condensation was a big problem internally.
In formulating a specification, breathability and ease of application was an important factor. The gable ends were overlaid with “Hofatex” breathable wood based insulation. KEIM Universal Render was directly applied to all elevations with KEIM Brillanputz top coat to provide a textured finish. The newly rendered elevations were then treated to 2 coats of KEIM Soldalit-ME. A minimum 20 year warranty was provided on the KEIM system. Condensation and mould growth is no longer an issue to the internal of the properties.
Design notesProduct selectionOutcome - The Result
Kerroo Coar, Peel is an estate of 66 social housing units under the management of Peel Town Commissioners. The properties have been undergoing various internal upgrades together with external upgrades such as new fascia’s, soffits & rainwater goods.
The existing external elevations are of original sand/cement spa dashed render.
The houses in Kerroo Coar are arranged in terraces. They are generally energy efficient houses with little external envelope, of which the majority is window or door. The issue is with the end gables where these houses have large external wall areas.
These walls had been cavity filled, but because of the construction defects, cold spots have occurred. Where the cavities have been rebuilt and new cavity fill inserted, it is evident that the earlier cavity fill does not perform to the higher standard of the newer products.
The issue of condensation, especially at gable end properties continued to an issue. The need for a solution to upgrade the thermal performance of the gable walls whilst allowing remaining walls to finished to match was paramount. A solution that would also negate the need to remove the recently replaced soil vent pipes was important.
For Kerroo Coar, a proposed system of increasing the thickness of insulation to upgrade to normal performance to offset the potential weakness in the existing gable walls (lack of cavity; poor insulation).
The Keim system was selected for several reasons:
1. The system uses a mineral paint rather than a self-colour render. This gives a similar product life to self-colour renders, but can be repaired and overpainted. The paint colour does not fade giving a much longer life than some self-colour systems.
2. The same paint can be applied to the existing rendered walls, allowing the whole block to be repainted in the same colour without over cladding.
3. The existing rendered walls can be over-rendered with a matching “thin-coat” breathable, flexible lime based render and painted to ensure a uniform finish with unrivalled longevity of finish.
4. Better insulation to remediate defects.
5. Longer life paint finish.
6. Ability to repaint remaining elevations without over cladding.
Keim developed a specification that would meet the needs of the brief with an emphasis on a superior application with a cost effective and long life outcome. Speed of application was also important in order to minimise site management costs and upheaval to tenants.
In formulating a specification, breathability and ease of application was an important factor.
1. 50mm Hofatex breathable wood based insulation installed to gable ends with proprietary stainless steel fixings.
2. Trueline aluminium base, edge and verge profiles and plastic corner trims as required.
3. Keim Algicid wash to existing elevations.
4. 1st coat render 6 mm thick KEIM Universal Render applied directly to existing substrate or insulation board; render incorporating KEIM Glassfibre mesh.
5. 2nd coat render (for textured finish) 3 mm thick KEIM Brillantputz render. Keim Brillant-Putz is available in different textured grain sizes and is a high performance lightweight render system ideal for application over insulation systems.
6. Protective and Decorative finish; 2 coats KEIM Soldalit-ME
Product warranty of minimum 20 years on the system specified.
A minimum 20 year warranty was provided on the KEIM system. Condensation and mould growth is no longer an issue to the internal of the properties.
• After 3 months completion of works – reports of vast improvement within the affected internal areas
• After 6 months completion of works – reports of issues resolved within the affected areas
• Hugely increased visual amenity
• Maintains breathability and moisture vapour permeability whilst providing absolute water repellence
• Absolute longevity of finish (minimum 20 years)