Curtain Walls

Describe unitised curtain wall systems

Unitised systems are pre-fabricated in modules off-site and delivered in panels. Unitised systems are better able to exploit the benefits of factory condition manufacturing and quality control require lower installation time on site

Front-sealed systems:

front sealed systems are totally impervious ( don't let water pass through) - rely on exact positioning of glazing panels to provide a totally weathertight exterior shell have limitations - their effectiveness is dependant on the quality of the workmanship during installation and the longevity of the sealing mastics essentially, front-sealed systems are only appropriate for use on low-rise buildings in sheltered locations, where the facade is likely to be changed in 10 years

Sticks vs Panels in Curtain Wall Construction Give 3 reasons for using Stick systems and 2 reasons against

+ve cheaper +ve less use of cranes +ve less technical +ve less movement problems -ve needs to scaffold -ve slower to fix

Sticks vs Panels in Curtain Wall Construction Give 2 reasons for Panel systems and 2 reasons against

+ve quicker to fix +ve no scaffold needed -ve more expensive -ve needs cranes and runways -ve must design for movements

Describe front-sealed curtain walls

-relies on outer seal for water resistance - usually 'mastic' or silicone -inner seal merely locates the glass -simple -easy to track leaks -favoured in the USA -associated with low rise construction

Describe drained and ventilated systems

-secondary sealed systems recognise that a totally weathertight seal is unlikely to be achieved for the life of a facade. Although they are designed to be weathertight, any water that does penetrate is collected and drained back to the outside through holes or slots. important that these drainage holes are large enough to overcome surface tension and winter icing. more complex US (and some others) think its 'crazy to put holes in a wall!'

What is a curtain wall?

A curtain wall is defined as thin, usually aluminium-framed wall, containing in-fills of glass, metal panels, or thin stone. The framing is attached to the building structure and does not carry the floor or roof loads of the building

What are the three basic designs of curtain walls?

Front sealed curtain wall Drained and ventilated (Secondary seal) Pressure equalised 'rainscreen'

What are the three curtain wall fabrication systems?

Stick Unitised Panelised

Describe stick curtain wall systems

stick systems are installed piece by piece on site, with the glazing inserted into the frame from the inside or the outside depending on access conditions. labour intensive economical method if designed, detailed and installed correctly, extremely reliable

When constructing curtain walls, you should test what causes problems List 4 factors that can cause problems for a curtain wall

water wind stability noise fire durability

Construction process for Curtain walls - Unitised curtain wall construction

- Offsite Factory Delivery - Unit Assembly - Unit Glazing - Unit Structural Glazing - Installation of Thermal Insulation - Pre-Glazed Units - Unit Racking - Unit Curing - Unit Shipment - Anchor Layout - Pre-Set Anchor Layout - Hoisting Units - Final Preparation - Unit Setting - Portable Hoist - Unit Setting - Installation

Construction process for Curtain walls - Stick construction

- Shear Block Application - Mullion Setting - Vertical/Horizontal Layout - Grid Layout

Describe Pressure-equalised systems

In these systems an outer rainscreen provides a protective barrier. Protected openings allow air ingress to a compartmentalised central cavity, which facilitates pressure equalisation. inner leaf is designed to be airtight The principle of the system is that the air pressure in the cavity changes in response to the external wind pressure, eliminating the pressure differential across the external seal which would otherwise tend to draw moisture into the cavity. cavity size is bigger than what's used in drainage and ventilated systems - to balance pressure effective compartmentalisation is required to cope with differential air pressures across the facade caused by vortices, separation, and funnelling. acknowledges that if -ve pressure builds up inside system then water will be sucked in. even more complex US (and some others) say its 'even more crazy to put BIG holes in a wall!'