National University of SingaporeSchool of Building And Real Estate

Bachelor of Real Estate/ Building (Part-Time)

BU1462/BR1105 ; CONSTRUCTION TECHNOLOGY IILecturer : CHEW YIT LIN (MICHAEL)

Semester : 2 ,CME 1

Tutorial Question 30: Discuss the various types of joints commonly used on building facades. How do these

joints act against the penetration of water, heat, noise, dirt etc.

By: AUNG ZAW NYUNT ( U 028521 U )

CONTENTS1.Introduction2.Various types of joints3.Building facades (more focus on light factories )

4.Joints act against the penetration of water

5. Joints act against the penetration of heat

6. Joints act against the penetration of noise

7. Joints act against the penetration of dirt / wind

8.Sealants

9.Case Studies

10.Mock-up façade

11.Defects

12. Conclusion

13.References

1.Introduction

FACADES JOINTS

• The building facade is major component in a building’s life cycle.An effective system is essential in contributing to a successful weather tight building envelop and in preventing infiltration of air and water.

• The high cost of energy for heating and air-conditioning is causing serious consideration of a good façade system. The long term financial impact of an inefficient system on the cost of keeping the building comfortable is now being calculated by building owners.

• Currently in Singapore, many sealants in high rise buildings are reaching the end of their life span.Many buildings in the city are estimated to require services in repair and/or replacement of sealants in the near future.

• An in-depth understanding of the causes of defects on building facades and their implications to design, construction and maintenance is important.

EXTERNAL CLADDING /WALL

• Functional specifications• a. Self-supporting between the framing members.• b. Resistance to rain and wind penetration.• c. Able to resist both positive and negative wind

pressures.• d. Provide the required level of thermal insulation.• e. Provide the required level of sound insulation.• f. Provide the required level of fire resistance.• g. Provide for the required level of natural

daylighting and ventilation.

•The underlying concept of the variable façade is that it should be able to react to the weather as flexibly as human beings can with their clothing.

•Are double-skin facades a solution in this respect?

2.Various types of joints

VARIOUS TYPES OF JOINTS

• The most common types of façade elements in Singapore; aluminium, natural stone(granite, marble,etc.) and glass.

• Others ; cement rendering, tiles( homogeneous ,mosaics, etc.), metal sheeting

• JOINTS• The need for joints arises because the necessity to link, lap or bond materials together when

providing the continuous and efficient weather enclosure for a building.• Unless the many interrelated factors which influence their position and type are very carefully

considered, they can form the weak link in the enclosure.• The first rule is to ensure that as much water as possible is kept away from this vulnerable

point where two or more materials are brought together, each perhaps having different characteristics and connected in some way with yet other types of materials.

• The designs for roofs and walls can provide shelter to their joints, or channel free-flowing water in predetermined directions to permit either collection or discharge to less damaging areas.

• The effects of wind-driven rainwater must always be taken into account in this respect, and boldly profiled upstands and overhangs at joint positions are desireable when it is difficult to form a continuous “membrane type” seal between two building components.

• The joints can be expected to behave in a similar manner to the surrounding surfaces by stopping water penetration at the outermost places; or by allowing water to be collected from its recesses and returned to the outside.

• Within these two extremes, there are a vast range of jointing possibilities(Fig.6.6).

3.Building facades( MORE FOCUS ON LIGHT FACTORIES )

4.Joints act against the penetration of water

FACADES JOINTS

• Wind and water penetration• Wind can cause direct physical damage by collapse or removal of parts of a building.• It can cause dampness by driving moisture into or through a building fabric, and also

excessive heat losses from the interior of a building by uncontrolled air changes.• Water penetration can produce rapid deterioration and cause the fabric of a building to

become moist enough to support life, including bacteria, moulds, mildew, other fungi, plants and insects.

• Saturated materials also permit the quick transferal of heat ( water is a good conductor ) and this, together with the other factors mentioned, will cause an uncomfortable, unhealthy and uneconomical building.

• The source of water likely to penetrate a building not only include those from rain and snow, but also those from moisture contained in soil or other material in immediate contact with the building fabric.

• For water to penetrate, there must be openings or passages in the building fabric through which it can pass, and a force to move it through.

• Without these two factors, the building fabric would remain in a watertight condition.• Most buildings have window and door openings, are made from lapped or jointed parts, or

from porous materials ready to absorb moisture; wind currents and eddies are also normally present.

The façade consists of different materials with variable runoff rates. Rainwater channeling is complex.

FACADES JOINTS

5. Joints act against the penetration of heat

FACADES JOINTS• THERMAL COMFORT

• A building must provide a satisfactory thermal environment for its occupants as well as for the mechanical systems it accommodates.

• Energy within the human body produces uninterrupted heat at varying rates in order to maintain an ideal temperature of 37°C in the internal organs.

• However, heat is lost by the body through radiation, convection and evaporation from the skin and the lungs, and there is a continuous process of adjustment to ensure a thermal balance between heat produced and heat lost.

• It is particularly important that the brain temperature is maintained constant.The factors in the local environment which govern heat loss include not only air temperature but also air movement, relative humidity and the radiant temperatures from surrounding surfaces.

• The fabric of clothing and of a building perform similar functions by maintaining temperature control through passive means which regulate natural flows of heat, air and moisture vapour.

• As a building involves a volume many occupants in different spaces, it must also provide active means for thermal comfort not unlike that achieved by the human body itself (fig.8.1).

FACADES JOINTS

• PASSIVE MEANS

• Simply stated, the creation of thermal comfort within a building by passive means involves the reduction of the rate of heat losses from the inside to the outside in colder climates, and the reduction of heat gains from the outside to the inside in warmer climates.

• In both cases the transfer of heat is regulated by the external fabric of a building which can provide varying degrees of thermal insulation.

• The type and amount necessary to achieve ideal conditions varies according to resources availability, climate of locality and the degree of exposure ( fig.8.2 ).

6. Joints act against the penetration of noise

The control of sound in a building must be considered from two aspects:

The elimination or reduction of unwanted sound generated by sources within or outside a building ( sound attenuation )

The creation of good listening conditions within a building where speech and music need to be clear, unmarred by sound reverberation and echoes.

UNWANTED SOUND

¥Figure 7.1 indicates the main ways by which sound can be transmitted into and through a building.

¥ This involves movement through air or other elastic media formed from solids, liquids or gases, aiirborne sound, or movement through a solid structure resulting from an impact force, impact sound.Both are transmitted by direct paths from source to recipient or by indirect paths along adjoining elements.

¥ High levels of unwanted sound, or noise, can lead to a breakdown in people’s mental health or even damage their hearing.Unwanted lower levels of sound are a nuisance and become a source of constant irritation, causing a loss of concentration.

FACADES JOINTS

FACADES JOINTS

NOISE INSIDE A BUILDING

¥ Modern society requires the increasing use of sound-producing equipment for home entertainment devices and the frequent involvement of noisy household appliances.

¥ These requirements often conflict with the simultaneous trend towards lightweight materials and less homogeneous methods of assembly used for a building.

¥ Joints in constructions are particularly liable to cause weak links when considering sound control as a problem.

¥ The method used to control the movement of sound within a building are similar to those adopted to control sound from external sources, although external sound is also reduced by weather exclusion measures, I.e. components having greater thickness and weights.

7. Joints act against the penetration of dirt / wind

8.Sealants

Sealant

Classi-fication

Uses Products Curingmethod

Features and Benefits

One-component type

Surrounding of glass plate and sash, Suspension method, glass-surf-board, glass made water tank and plastic, etc.

KE42 Aceticacidtype

General use. High modulus, Strong adhesion. Quick hardening.

Surrounding of glass, transparency-required places from beauty viewpoint

KE420 High modulus,strong adhesion. Highly transparent type.

Surrounding of glass and sash, Suspension method, glass-surf-board, mortar, marble and stone materials, prefabricated house and its surrounding, clean room, surroundings of metal, etc.

Sealant45

Oximetype

General use. High modulus. No corrosion property

Place to be moldy (kitchen, bath, toilet, refrigerator, fixed temperature and humidity room, clean room)

Sealant4588

High modulus. Fungicide (Anti fungus).

Sealant

Classi-fication

Uses Products Curingmethod

Features and Benefits

Two-component type

Big joint parts, metals, top beam, Al-made curtain wall, glass, sash and their surroundings, plant, tank, etc.

SealantNew 70

Aminoxiytype General use, low modulus.

Movable horizontal joint parts. Civil engineering use

Sealant701 Low modulus, fluidity.

Sealing of fire-preventive section

Sealant74 Low modulus, flame resistance (60 min).

Three-component type

Oil type coking repairmant, Weak or hardly adhered materials

Sealant79

Sealant with plasticity. (Hardened surface & mastic inside)

9.Case Studies

As built configuration of a high-rise office building curtain wall completed in 1984.This appears to be an elegant design satisfying the key functions of all exterior building

envelopes: aesthetics, resistance to water and infiltration, thermal isolation, and structural performance. One small detail was overlooked, however.

CASE STUDY 1

CASE STUDY 1

CASE STUDY 1• Incompatibility

• Although not a good detail, in this instance the single sealant bead around the windows should not have been a problem until the material reached the end of its design life.

• But a compounding problem caused premature failure: the perimeter joint sealant material(a polyurethane) was incompatible with the internal window extrusion joinery sealant (silicone ).

• The polyurethane disbonded and curled away from the joinery sealant where the two were in contact at the mitered corners of each window.

• Although only a small defect, the cumulative effect was equivalent to poking 12,000 holes in the building envelope.

• To remedy the problem, the window perimeter sealant was cut out and replaced.

• Special care was used in cleaning the window frames of any sealant residue, which had originally exuded from the mitered corners, causing the problem in the first place.

CASE STUDY 2

CASE STUDY 2

CASE STUDY 2

1st OCTOBER 2001

CASE STUDY 2

#Finding :Rain water seeped into corridor through crack at the external wall @ Sunlight Electrical Light Factory, Ubi Ave 4

#Solution : Seal up visible cracks using high pressure grouting and sealant follow by painting ( expensive repair involving high external access ): Best to use stretchable material in case same spot open up again!: Provide 20 ∅ spout pipe below the aluminium cladding at roof

#Failure Mechanism : poor design in joints of aluminium cladding at the roof:rough stone effect external finish delayed the rate of run-off of any water landing on it.: lack of coordination between aluminium cladding and 115 thk brick wall with spray texture finish interface

: cracking

10.Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

Mock-up façade

• The HALFEN Curtain Wall Support System provides adjustable support for framed façade systems. Adjustable brackets used in conjunction with HALFEN channels provide a fast and simple method of restraining both the weight and wind loads imposed on the façade. The system may be used on either steel frame or conventional concrete frame structures, and is available in different designs to enable rapid mullion installations to either the top or edge of floors and beams.

Quality features are: • Fast and safe fixing, allowing immediate full load application • Easy adjustment in up to three directions • High load-bearing capacities • Close edge distances • Installed without special tools • No power supply required for installation

11.Defects

12. Conclusion

conclusion• I have highlighted several common problems in building facades.• These problems have implications in the design, construction and

maintenance of buildings.• Designers, contractors and owners have an important part to play in

the prevention and resolution of these defects.• It highlights the need for greater communication and better

coordination between parties during the various phases of the development in order to alleviate these problems.

• Then, hopefully, the need for more innovative joints concepts / materials will be filled by continuous searching of innovators from around the globe.

13.References

FACADES JOINTS

• REFERENCES• 1) M.Y.L.Chew,C.W.Wong,L.H.Kang(1998) “Building Facades-A Guide To Common Defects In

Tropical Climates”, World Scientific• 2) Geoffrey K. Cook & Dr. A.J.Hinks (1992) “Appraising Building Defects- Perspectives on Stability

and Hygrothermal Performance”,Longman Scientific & Technical• 3) Mauro Moroni & Piermaria Sartori (1994) “ Dealing with Defects in Building”, BE-MA editrice-

Milano-Italy• 4) Oesterle. Lieb. Lutz. Heusler (2001) “Double-Skin Facades- Integrated Planning”, PrestelVerlag-

Munich• 5) David H. Nicastro (1997) “Failure Machanisms in Building Construction”, American Society of Civil

Engineers Press-New York• 6) Derek Osbourn, Roger Greeno (1997)“Introduction to Building-Second Edition”, Longman• 7) http://www.shinetsu.co.jp “silicone sealant product”• 8)http://www.halfen.com “curtain wall façade”• 9) Site experiences “Sunlight Electrical Light Factory, Ubi Ave 4”• 10) M.Y.L.Chew (2001) “Construction Technology for Tall Buildings-2nd Edition”, Singapore University

Press-World Scientific

AUNG ZAW NYUNT ( U 028521 U )