Cladding and Render Applications

Cladding and Render Applications

The steady growth in popularity of off-site construction methods, and the drive to improve the performance of the external envelope, is seeing sophisticated cladding systems applied to far more types of structure than was previously the case.

Where curtain wall systems tended once to be confined to commercial contracts, they now appear on all categories of building; while the use of rainscreen cladding and external wall insulation (EWI) has grown exponentially in an effort to reduce heat loss. In all instances, though, it is imperative that the insulation material chosen not only offers the necessary thermal performance, but also facilitates correct and repeatable installation.

Beginning with EWI, or insulated render systems as they are also known, there are a number of proprietary solutions on the market that lend themselves to both new-build and retrofit applications, on non-residential developments, as well as low, medium and high rise domestic dwellings. 

Depending on the type of structure under consideration, and the soundness of the substrate, the specifier can choose between two main types of system, where the insulation is either mechanically anchored with a series of drilled fixings; or is bonded in place on the outside of the original wall using special adhesives. There is also an alternative where the insulation is encapsulated in a light gauge reinforcing cage in order to strengthen the completed elevation. 

The installation is then completed by applying multiple coats of polymer or acrylic render, generally employing a lightweight mesh to offer greater impact resistance. Depending on the thickness of insulation specified, the performance of old buildings can be improved close to that required by the current Building Regulations; while contemporary constructions have contributed to near zero carbon solutions.

Curtain walling systems tend to be fully factory finished, ready to be ‘hung’ on brackets secured to the building structure, with mineral wool frequently being the preferred insulation material due to its non-combustibility and excellent acoustic properties. And these same attributes see MIMA members’ products widely specified for rainscreen systems as well.

In retrofit situations the insulation is fixed back to the building substrate, between the cladding rails or timber battens, greatly enhancing the thermal performance of the envelope; while still maintaining a ventilation space behind the external panel. This also allows the building interior to continue benefitting from the effect of thermal mass.

Where light steel sections are employed to form the exterior walls to buildings, the insulation is normally introduced in two positions. Firstly a flexible product is friction fitted between the metal studs, being sandwiched between the plasterboard lining, with a vapour barrier, and a cement fibreboard sheathing fixed to the outside. Mineral wool slabs or batts are then secured to the outside of the boarding, while the support brackets (separated by a thermal break) are fixed back to the main studs, ready to take the rainscreen cladding.

In all instances, the contractor, consultant, client and building occupant benefit from mineral wool insulation’s unrivalled range of attributes: being manufactured from a plentiful raw material with relatively low embodied energy; offering straightforward utilization while providing fire protection and significant sound reduction. It is the insulation solution that answers all the questions asked of it.