|Building Structural Elements|
NAME: KENNETH KEANE.
COURSE: CIVIL ENGINEERING & BUILDING.
LECTURER: Mr. A. MUNNS.
SUBJECT: BUILDING STRUCTURAL ELEMENTS.
This case study was intended to provide us with the opportunity to study two different solutions to the problems associated with cladding a building. The two buildings I have chosen to study are actually in Dundee. The first building is the University of Dundee, Tower Building. The second building is also a University of Dundee building. It is the Computer Centre in Park Place. The two building are used for computing and IT services, so therefore have the same requirements from the buildings. Obviously, they both satisfy the requirements but have completely different facades and are no way similar in appearance.
Cladding a building is not as straightforward as one might think! The popularity of framed buildings has increased in the last number of years, which means that enclosing the walls can be considered as non-loadbearing, that is the cladding must be able to support itís self-weight and any wind loading. Walls can be designed as a complete envelope using brickwork panels, precast concrete panels or lightweight wall claddings. Many problems do arise when choosing a cladding type. The final choice will depend on such factors as;
The proposed cladding must be suitable to the building materials used on the project. New buildings must blend in with the buildings around it.
..Local Planning Authority requirements:
The proposed cladding must be suitable to the surrounding areas. New buildings must blend in with the buildings around it. This prevents the construction of "eye-sores".
..Short and long term costs:
The short-term costs are simply paying for the cladding and its erection. However, the long-term costs are much more important in the long run. These costs include repointing, washing & cleaning,
If image were very important to the client/company, the factor would be very important to them.
The requirements are basically the same for both buildings, so therefore there was no special requirements or particular reason to go for any type of cladding over another type. None of the occupants were annoyed or disturbed during this exercise. This was just a study of the buildings from the outside; no materials were removed or exposed in the completing of this work. From this report, you should be able to understand the basic requirements from the clients' point of view and you should be able to identify the aspects of the design, which you consider to be a success or a failure.
For you, the reader to fully understand the study of these two buildings, you must understand the requirements of a wall. There are many functional requirements for an external wall of any building.
This is a long-term concern for the client. Long after the builder has finished his work, the finish on the external leaf will begin to weather. As in most buildings, the walls never weather at the same rate. Shelter from the elements, broken gutter pipes etc. all cause different situations. If the client has a commercial business then appearance is very important to him/her. It is his business to attract customers into the premises.
Computer Centre, 3 Park Place:As you can see from the digital photo, there is definitely adequate access provided to this building. There is also enough masonry or blockwork between the openings. This ensures that there are no weak spots in the cavity wall construction. The openings are evenly spaced on the face of the building; this not only makes it look good but eases construction also. From the next photo, it shows that there is a parapet wall built up on top at the eaves of the pitched roof. This adds to the strength of the building and may also provide access all around the roof edge. This could provide access to maintenance people or even the emergency services, such as the fire brigade.
Adequate Acess & Natural Daylight:
Access to the ground floor of the Tower Building, is very good. This photo shows exactly how good it actually is. This is more than adequate to deal with the mass of students that use the facilities in the building. The opening is very structurally secure, as there is probably a reinforced or precast beam spanning over the head of the door/glazed area.
All access to the multi-storey section is provided through the front and rear entrances. This does not really effect the strength of the building, as the ground floor area is built around the base of the tower. The main glazed area is at the corners of the building. This would be a cause of concern for me. The main reason being the lintel support, even if there is a reinforced concrete beam at the head of the windows, from the photos it seems that there is only a 300*300 column at the corner to support the next level.
Front and rear elevations of the building.
Adequate Acess & Natural Daylight:
Computer Centre:In my opinion, the fire resistance of the internal leaf of this building may be poor. From this photo, you can clearly see that the ceiling heights of the rooms are bigger than normal. (In a normal building, it is roughly 2.5m.) Ceiling heights, like this building are common in older buildings, so therefore, it must have been refurbished/redecorated in the past at least once. The internal walls are probably dry-lined, to conceal the old plasterwork, new electrical wires and fittings and to prevent dampness. This is a common practice for older buildings. The external leaf of this building is stone cladding, sometimes being called "Ashlar Walling". This would be easily stained by fire damage and cannot be painted over like normal plasterwork. This would have to be either power-washed or scrubbed dry.
Tower Building:In my opinion, the Tower Building is not as fire resistant as the Computer Centre. The external cladding on the outside of this building is comprised of two materials,
The stone work is just as good as the cladding on the Computer Centre, but the timber sheeting is a fire hazard. The internal leaf of the Tower Building is fairly new, so therefore there is probably a plaster finish all over the inside walls. This eliminates any extra fuel, such as dry lining, for a potential fire. The timber sheeting panels are long and in one piece. If a break (concrete column) was provided in the timber panels, it may slow down the spread of the potential fire.
The Computer Centre is a very durable building and obvious doing the job it was intended for. The material itself looks and feels porous. It has stood up pretty well against the weathering process. The wind and rain has not worn or cracked it too much. On the down side, the external wall is heavily stained. There are many reasons for this. If the material is porous, it may hold water and could lead to the growth of algae. For the picture above you should see the staining encircled in white. The algae could be green or black. It is very common at the base of many buildings, due to the presence of moisture. Another reason of the irregular staining is the irregular shading provided by the trees and surrounding buildings. The wind and falling leaves provide dampness to the building. The heavy black staining is even more evident further down the road. Traffic pollution is also a contributing factor to the heavy staining as there is a heavy goods delivery point nearby.
Tower Building:From this photo, I hope the staining is evident After a certain period of time, it is expected that all materials will weather to a certain extent. Materials like the timber panels will weather a lot faster than the natural stonework. This is why timber sheeting has to be treated with some type of preservative. This lengthens the life of the material.
Computer Centre:This is one of the front windows in the Computer Centre. As you can see, this is a fairly old type window. It is made of wood, probably teak, and is single glazed. The thermal and sound insulation properties are not very high on this particular window. Double glazed windows are obviously better at keeping out the sound pollution that could come from the street. Double-glazed are again better at keeping the heat from escaping also. Single glazed windows have a history of problems with condensation and dampness. The reoccurring dampness will eventually begin to effect the timber frame of the window. This in turn may effect the timber sash at the top, causing it to swell and get stuck.
The windows in the Tower Building are much more modern and therefore better. The windows are double-glazed, so are better at insulating the heat and as a sound barrier. There are also bad points to note. The window frame is made of Aluminium. This is strong and durable but also a heat conductor. Condensation is also a big problem with aluminium windows. This was one of the reasons they were replace by the newer uPVC material. They large area of glazing is not the ideal situation for sound insulation as sound can travel out one window and into another! However the canopy should muffle the sound of most students entering the building below.
Durability & Maintenance
The maintenance level of the Computer Centre is fairly low. Since it is a natural stone cladding facade, there is no need for painting yearly. However if any edge or quoin stone gets damaged, it is very hard to repair the damage. The whole stone may be replace if it is necessary but the colour of the new stone will not suit the old weathered stones. Artificial fillers may be used to repair cracks or chipped corners but again, the colour will be noticeable. The natural stone on the Computer Centre is a "rustic red" colour and this seems to show up the black and green staining a lot. The corbels at first floor level and at the ground level are the most noticeable areas for staining on this building.
The maintenance on the timber single glazed windows should be done yearly, more if necessary. Timber windows are very susceptible to rotting unless they are given the protection they need. The windows need to be sanded and painted every year. Some will even need to be planed due swelling or due to the build up of the layers of paint over the years. Cleaning the external walls would be a major job, it would have to be power-washed or sandblasted for a worthwhile lasting effect.
Durability & Maintenance
The durability of the Tower Building seems to be far better than the Computer Centre. From the various photos, we have seen that the natural stone finish on the Tower Building seems to be withstanding the weathering process a lot better than the red stone finish on the Computer Centre. The natural stone finish on the Tower Building is weathering together and has no signs of pattern staining. The pointing is the only concern I have for such a high building. The whole building is surrounded at the base by the ground floor, so the scaffolding may have trouble finding secure footing. The timber-sheeted panels are in very good condition, but need to be kept that way. This means a lot of maintenance over the coming years.
During the course of this project, I realised that construction techniques do not change much between close countries but the construction materials and shapes of buildings do. Firstly, taking into account the aesthetics of both buildings. It is in my opinion that the Computer Centre at 3 Park Place easily wins. The actual shape of the building and how it fits into its surrounding are the main points. Both the buildings provide adequate access, but the Tower Building is purpose built for a crowd entering. The Computer Centre is adequate but not up to the standard of the Tower Building. Both provide adequate lighting and ventilation to the internal rooms. The Tower Building, in my opinion, is the better of the two regarding fire resistance. The Tower Building has got timber sheeting on the external wall but I am assuming that the Computer Centre has dry-lined walls on the internal leaf. Since most fires are started from the inside, especially where computers are concerned, this poses the greater risk of the two. The Tower Building seems to be holding out the best against the elements also. The dark staining of the red stonework is very displeasing to the eye. The Tower Building narrowly wins the sound insulation comparison. The Tower Building has standard size double glazed windows which helps keep out any sound pollution. On the downside, they do have the very close together, so sound may travel from room to room. The Computer Centre has only got single glazed, often, oversize timber windows to compare with the more modern approach of the Tower Building. The Computer Centre has the good thermal properties, as it is more sheltered and has a pitched roof with rooms in it. The building has high ceilings and single glazed windows. The Tower Building is of a more modern construction with double glazed windows and standard style windows. In my opinion, it is obvious that the Tower Building has the best features all round, even when it comes to maintenance and durability. Even the timber-sheeted panels outside are easy maintenance compared with the staining of the natural red stone or the timber windows! The designers or the builders of the Tower Building succeeded in their job of finding a cladding that works well. The cladding is actually pleasing to the eye, it does not attract the attention. (Considering it is a multi-storey building, that is an achievement!)
I have stated what I know are the facts of this study. I hope that through the reading of this project you will appreciate the number of questions that must be answered before a type of cladding is decided on.