Ventilated cladding systems: structural and drainability performance criteria

Luiz Fernando Batista Da Silva,Ercio Thomaz,Luciana Alves De Oliveira

doi:10.1590/s1678-86212018000300285

Luiz Fernando Batista Da Silva, Ercio Thomaz + Show 1 more

Open Access

https://doi.org/10.1590/s1678-86212018000300285

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Journal: Ambiente Construído	Publication Date: Sep 1, 2018
Citations: 4	License type: CC BY 4.0

Affiliation: Instituto de Pesquisas Tecnológicas

Abstract

Abstract Cladding systems have significant effect on the performance and durability of building façades, contributing to the building watertightness, property valuation, aesthetic finishing, and decoration. Non-adherent cladding, also named rainscreen cladding or ventilated cladding, is currently used in residential and commercial buildings, new constructions, or retrofit operations, and it is considered an efficient measure to improve the moisture safety of building envelopes. Therefore, the absence of Brazilian normalization to ventilated cladding systems is one of the difficulties limiting its increased local application. In Brazil, a technical standard, NBR 15575, parts 1-6, (2013), establish the general performance requirements and test methods to evaluate residential building systems including structure, wall, floor, coverage, and hydraulic installation. However, this standard cannot be integrally applied to the cladding systems because it was developed considering the vertical wall system as a whole. In this study, we propose the criteria and test methods for assessing ventilated cladding systems while taking into account the structural safety (wind loads resistance, hard and soft impact resistance) and drainability requirements. The following activities are performed: literature review, practical case study, and tests on prototypes for validation of the proposal. The tests allow verification of the feasibility of the criteria and tests methods proposed. In addition, the proposal makes it possible to guide design, construction, and maintenance needs, thereby inducing the growth of this technology in Brazil.

Highlights

Façade systems are comprised of several layers such as a wall and cladding, of which the latter is the most exterior layer and it may or may not be bonded directly to the substrate.According to some previously reported publications by Resende, Barros e Medeiros (2001), Ribeiro and Barros (2010), and Becere (2007), a cladding system has a significant influence on the performance and durability of a façade as it contributes to the building watertightness, valorization, aesthetic finishing, and decoration.One of the cladding technologies currently being used in residential and commercial buildings, new construction, or retrofitting (Figure 1), is the nonadherent cladding system, named as rainscreen cladding or ventilated cladding
The current work has been developed based on the the following activities: (a) bibliographical review: information relating to ventilated cladding systems reviewed, for instance, manuscripts, theses, and national and international technical standards
For drainability assessment, we propose calculating the relation between water sprinkled and water captured during the test, i.e., water that reaches the substrate and water collected. Such information will make it possible to analyze if waterproofing the substrate and the air space thickness specified in the design are suitable for promoting watertightness of the external wall

Summary

Introduction

Façade systems are comprised of several layers such as a wall and cladding, of which the latter is the most exterior layer and it may or may not be bonded directly (adhered) to the substrate (wall). The lack of Brazilian normalization in reference to ventilated cladding systems is one of the difficulties in homogenizing their design, construction, and use while taking into account aspects related to safety, habitability, durability, and maintainability This impacts the decision-making phase in which the façade technology is selected. In Brazil, NBR 15575 (ABNT, 2013), a general performance standard applied to residential buildings, sets the requirements and evaluation methods for the five most important building elements, namely, structure, wall, floor, coverage, and hydraulic installation This standard cannot be adopted for the cladding system as it applies to the entire wall system. NBR 10821 (ABNT, 2011a) provides some of the requirements and evaluation methods for structural performance (wind loads) and durability that can be adopted for the ventilated cladding systems.

Research methods

Design example

Methods and results of tests

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