MIND YOUR WALL CLADDINGS – PART 2

Proper on-site management of wall cladding is critical to delivering quality buildings. This article is the last instalment of a series talking about specific storage requirements for cladding types

Wall claddings are what we see when we approach a building, and any defects from poor handling, storage or installation may be visible. They can also affect the durability of the cladding.

Prefinished profiled or plank metal claddings

There is risk of damage to the prefinished surface and denting of the materials. Once installed, they must be protected from cement splashes that can mar the surface.

Store under a water-resistant cover, clear of the ground to provide airflow around the bundle.

If the material has become wet during transportation or in storage, wipe it down to remove moisture and then fillet or cross stack it to ensure air circulation between the sheets.

If sheeting has been wet in storage for more than three days, it should not be used because of the permanent surface staining that may have occurred.

When handling and storing:

• Evenly position the materials on untreated, evenly spaced dunnage to prevent deformation – packs should be no greater than 1000 mm high and on a slight incline to allow water run-off.
• Store the material in the order it will be installed.
• Peel and lift the sheets off the bundle – do not slide or drag sheets or planks across each other or over rough surfaces.
• Sheets or planks longer than 3m should be handled by two people and carried on their edge to avoid buckling.
• Keep material clear of any substances that may cause damage.
• Tie down stored material and accessories, as they are susceptible to wind damage.
• Strippable protective film must not be exposed to sunlight or UV during storage – remove the film immediately after installation.

Zinc Claddings

Transport and store zinc claddings under dry, ventilated conditions, so white rust does not form. Avoid any contact between wet sheeting or tarpaulins and the surface of the metal during storage.

For good transportation and storage of zinc, ensure:

• Good air movement around stored materials.
• It is stored on dry, covered pallets on a dry floor.
• It is tightly stacked to prevent chafing.
• Sheets are protected from abrasion.
• Material can sit unopened for several days to allow for acclimation to the storage area’s temperature and humidity.
• Acidic perspiration and fingerprints are immediately removed – wear clean gloves when handling material during transportation, fabrication and installation.
• All strippable film (PVC) is removed as soon as possible after installation – partial removal may give an uneven patina. Avoid shopapplied protective films as these may trap air and moisture leading to formation of zinc hydroxide stains.

Glass as a cladding

Glass used as a curtain wall cladding material is arguably the most fragile material covered here and, when used with some other claddings, the most susceptible to damage. Handling and storage requirements for glass include:

• Leaving the glass within any protective crating until use.
• Storing individual sheets of glass on edge supported by dunnage with an isolating layer between sheets.
• Storing and handling away from metal and other brittle materials and operations such as placing concrete.
• Keeping the glass dry.
• Using the correct lifting apparatus to prevent edge or surface damage.
• Securing the glass back to a rigid structure to prevent overturning.

Metal-faced panels

Metal-faced panels with aluminium, steel or magnesium oxide board come in various options, including thin-stressed, prefinished aluminium or steel skin panels with a polystyrene or polyurethane foam core in several thicknesses.

While more commonly used on commercial buildings, both panel types are utilised as wall cladding systems on residential buildings.

Ideally, panels should be delivered and lifted into their final position. If they need to be stored:

• Stack clear of the ground on evenly spaced bearers.
• Leave the protective film in place until panels are installed.
• Fully cover to keep them dry.

Exterior insulation and finish systems

Specific material storage and handling requirements for exterior insulation and finish systems (EIFS) – polystyrene overcoated with acrylic or polymer modified cement plaster – include:

• Storing polystyrene sheets under cover on a level platform protected from UV.
• Providing a dry storage area for the powdered components of the plaster.
• Minimising exposure of the polystyrene to UV once erected – any yellowing of the surface from UV must be removed before plastering commences.

Precast concrete

Precast concrete component deliveries should be planned so the panels can be lifted directly into position and braced. Where panels must be stored, they must be placed on strong and level supports positioned so precast components are not subject to excessive stress.

Recommended quality control checks include:

• Structural defects – cracks.
• Dimensional tolerances are within the limits specified.
• Surface finish quality is as specified.
• Physical damage – chipping or staining.
• Shrinkage cracking.

Lightweight aerated concrete

Lightweight aerated concrete is supplied as panels or blocks that are then plastered. Storage requirements include:

• Providing dry storage for panels and blocks and components of the plaster system.
• Avoiding sagging or damage to ends, edges and surfaces.
• Storing uPVC accessories flat and protected from direct sunlight.
• A maximum stack height of two panel bundles.
• Stacking panels on edge on dunnage.

When handling lightweight aerated concrete:

• Utilise supplier-developed handling systems such as hoists, lifters and trolleys — some suppliers require the use of approved lifting devices for unloading and moving materials.
• Keep manual handling to a minimum for larger items.
• Ensure appropriate bracing is installed to packs prior to removal of strapping to prevent panels from falling.
• Packs should be unloaded and stored as close as possible to the intended installation area.

Cladding system components and accessories

Some cladding systems require the application of plasters or use of mortars to complete the installation. Store dry components such as:

• Cement and finishing plasters in a dry, protected area.
• Sand covered to protect from contamination such as dirt and cat faeces.
• Fibreglass mesh protected from sun.
• Flexible wall underlays under cover to protect from damage, water and UV.
• Bright steel nails in dry conditions.

Liquid or flexible components must be stored in frost-free conditions. There are also recommended temperatures that should not be exceeded. Silicone rubber stored at 27°C, for example, will have a shelf life of about six months. Material stored at 38°C will have a shelf life of about two months.

It is also important to rotate stored stock such as cement, primer, sealants and adhesives to ensure material is within its use-by date.

This article was first published in BRANZ’s Build 172 magazine. www.buildmagazine.co.nz. Words supplied by BRANZ.