Level 3 - Facades Flashcards
On South Kensington, you advised on cost ranges for different façade specifications of unitized faces, what was the advise you gave?
I reviewed the affordable and private residential facades and prepared a benchmark presentation which indicated that the affordable was benchmarking high when compared to other projects as it was the same specification as private.
What was the materiality of the South Kensington Facades?
Affordable:
- Reconstituted Stone
- Brick facing precast concrete with expressed columns
- Full height double glazing
- Aluminum Louvres
- Aluminum Cladding to top floor
- Zinc Cladding
Private:
Similar materiality but also had ‘hit & miss’ brickwork & Zinc Panels and expressed columns
What was the most expensive material on the facade at South Kensinton?
Full height glazing - £1,200/m2
Brick facing precast concrete panels - £1,250/m2
What is the difference in affordable and private residential façade costs?
Affordable - £600 to £1,400/m2
Private - £950 to £1,850/m2
What is a Stick system facade?
Stick systems area cladding systems which are constructed on site.
Different elements or materials are delivered to site and the facade is installed piece by piece
What is a Unitised facade?
Unitised systems are prefabricated off site and delivered and installed straight away as panels.
How are Unitised facades installed?
They are typically lifted to location via a crane and installed from the inside of the floor plate
Panels are then fixed back of cast in to the structure using brackets and bolts
What are advantages of a Unitised Facade?
Time - Installation time is shorter than stick
Cost - Lower labour costs (as a result of faster installation)
Quality - High quality are fabricated and glazed in a climate controlled environment
What are the disadvantages of a Unitised Facade?
Time - Longer lead in / fabrication time
Cost - May require materials off site payments
Quality - Only suitable for buildings with repetition
Not suitable for smaller projects due to lengthy fabrication time and cost
What are the advantages of a Stick Facade?
Time - Materials readily available and allow for earlier installation on site
Cost - Can be more economical for smaller projects
What are the Disadvantages of a Stick Facade?
Time - Installation on site is longer
Cost - Additional time related prelims on site, scaffolding and labor costs
Quality - Installed on site in unpredictable conditions - harder to achieve same quality as when made in a factory
Not suitable for Materials require space on site to be stored
Can you summarize the advantages / disadvantages of untised and stick facade systems?
Unitised:
Time - quicker installation, longer lead in times
Quality - higher quality product (made in factory)
Cost - More economical for larger projects (economies of scale)
Stick:
Time - Quicker lead in time, longer installation on site
Quality - parts fabricated on site in unpredictable conditions, not as good as unitsed
Cost - More economical for smaller projects
Why did you advise on a Unitised system for South Kensington?
Due to the scale of the project it could be more economical using unitised façade, there was lots of repetition on the buildings and would speed up the construction programme.
By using a unitised system a high quality product be guaranteed due to being made in factory conditions and not on site.
This was also a tight site and therefore unitised was preffered as materials did not have to be stored on site
What did you advised the client on cost ranges for different unitised facades on south ken?
I advised the Client on typical costs of private and affordable residential facades.
Using a bar chart I was able to compare the £/m2 (Facade) against similar projects.
By doing this I was able to demonstrate to the Client the relationship between £/m2 of facade against targeted sales values.
This indicated that South Kensington was at the higher end of the scale and that VE opportunities could be reviewed increase value for the Client
Can you give some examples of unitized facade specifications ?
Low spec (£700 – 850/m²) • Highly repetitive • Mainly Glass and aluminium • Uncomplicated with little articulation • Sensibly sized
Mid spec (£900 – £1,150/m²) • Increased variation • Mainly glass and aluminium • Greater articulation • Taller Units
High spec (£1,200+/m²) • Brick slips, Terracotta, GRC • Deeper reveals • Little repetition • Projecting windows
What elements of the Façade were key Cost drivers?
Glazing and articulation
- Glazing - £1,400/m2 Unitised Panels
- Pre cast concrete panels - £500/m2
- Brickslips - £250 - £400/m2
- Stone Cladding - £200 - £350/m2
What was the build up of the unitised panels
- Unitised glazing
- Brick Slip Cladding
- Pre Cast Concrete Substrate Panel
- Insulation
- Vapour Control Layer
- Waterproof Barrier
- Internal Wall Lining
- Internal Wall finish
What are the factors which impact Unitised or Stick?
Quality is better with unitised and quicker on site programme. Good for bigger projects with lots or repetition in the façade.
Stick materials can be delivered to site quicker but has a longer on site construction programme.
Why was unitised preferred on South Kensington?
On South Kensington I advised on the use of unitised due to the quality and on site construction programme would be quicker.
South Ken development was around South Kensington Tube station and the station may have to be shut down at certain times to allow work to progress, weekend working was required and therefore speed of the construction programme was a big benefit.
Commercial, what do you need to consider / allow for when pricing a unitised system?
Crane
Allow for road closures
What were some of the Value Engineering Opportunities you advised on, on South Kensington?
Articulation – in doc
Standard size brick – in doc
- Removing expressed columns
- Less detailing
- Simplification of glazing elements – using a standard range
- Increased solidity
- Simplify layering or materials
What was the saving in moving to a standard size brick?
Material Costs:
Standard brick - £50/m2
Long format - £160/m2
What are U Values?
Measure thermal transmission properties of the facade
The better the U value of the façade the less energy is required to maintain comfortable conditions within the building
What are R values?
Measure thermal resistance
