JS Construction Tech

Question 1

What methods or processes were used to gather data for your cost comparison on the strip foundations and piled foundations?

Answer 1

I used in house benchmarking in order to obtain a cost /m2 GIFA allowance, given the stage of the project. I also then compared these costs against a recent tender I had received for mini piles

Question 2

Why did the Structural Engineer propose to switch from strip foundations to mini piles?

Answer 2

The amount of cut and fill on site meant the subsoil was a lot weaker in areas there there was a high quantity of fill. This meant mini piles had to be used in order to reach a firm strata.

Question 3

What was the outcome of the cost comparison?

Walstead Park fnds

Answer 3

A mini pilled foundation was more expensive so there was an increased costs. However, the structural engineer advised it was too unsafe and unstable to use a strip foundation

Question 4

How did you do the cost comparison?

Walstead Park fnds

Answer 4

I considered the different cost items in a strip foundation which included concrete, rebar, formwork, excavation and compared it against the cost for a mini piled, using benchmarking where possible

Question 5

On Gillingham House, can you tell me what you did?

Brickslips

Answer 5

The client had proposed a precast concrete system for the brick-slips and the client asked for a cost comparison against a traditional method. Although the traditional was cheaper, a rate of £450 a m2 was provided to me by the subcontractor, the brick-slip was preferred due to ease and speed of construction, and quality assurance. The client then asked me to provide a cost comparison against s SFS system

Question 6

What were the cost differences between the SFS and PCC

Answer 6

I had a rate of £1,4750 for the SFS system, which was built up of the frame, brick slip, fire barriers etc and a rate of £1,593 for the PCC system, which was provided by a supplier

Question 7

How did undertake your cost analysis on Wandon Road

Answer 7

As the current roof space just had plant located on it, I spoke to the MEP team about the scope that would be required. This included relocating the all the heavy plant equipment elsewhere. The MEP consultant confirmed the cabling and pipework can stay if a timber deck was placed over. There would also be costs to provide some new MEP such as external lighting. I then spoke to the SE about any structural strengthening works that would be required

Question 8

Other than MEP, architectural and structural, was there anything else you needed to consider?

Answer 8

There are regulations regarding roof gardens as part of the Building Reg. Part B. If the client wanted to proceed with this option they would have to consultant the fire consultant.

Question 9

L2 - How did you build up the costs for the new roof garden?

Wandon Road

Answer 9

On another project, I had the same type of scope where an existing roof was to be made into a roof garden, so I was able to benchmark a lot of the items using rates the tenders had returned. There would also be a requirement for new safety measures to allow footfall onto the room.

Question 10

Did the client want to go with this option?

Wandon Road

Answer 10

It was very much a nice to have item, as the costs were way above the budget, the client proposed not to go with it.

Question 11

What was the basis for your advise that underpinning would be required?

Question 12

How did you present your assumptions to the client on the Horiato’s?

Answer 12

I issued the client a report, with the costings and our assumptions listed out. As the client had no construction background, and where a charity, I spent time explaining the different construction methods required and what we have costed.

Question 13

Are we, as QSs, in a position to be advised on design?

Answer 13

No, I made it clear within the report that any further action on the project should include the appointment of a structural engineer and architect. I was only presenting the costs and listing out the different assumptions I had made.

Question 14

How did you cost the works if there was no design?

Horatios Garden

Answer 14

For the lift itself, I spoke to the market to obtain 3 quotes for a new platform lift, which included works required to facilitate the lift, such as new foundations. For other works I had assumed, I was able to get costs from other projects of a similar nature and allow for provisional sums within the costings for these works. I also spoke to different colleagues of mine for advise on my costings and other elements of works required.

Question 15

What’s the difference between bored piles and driven piles?

Answer 15

Bored a hole is excavated and concrete is then poured into it, driven are usually precast and driven into the ground

Question 16

When would you use bored over driven

Answer 16

Small site in a built up area to reduce noise and vibration

Question 17

What was the build up for the external wall on Gillingham house?

Answer 17

Brick slip, insulation, SFS, sheathing board, insulation, vapour control barrier, plasterboard

Question 18

What are the advantages of a Steel frame?

Answer 18

Faster erection,
More sustainable as you can recycle,
Lighter than a concrete alternative
Good Strength

Question 19

What are the disadvantages of a Steel Frame?

Answer 19

Thermal / Acoustic Performance
Typically more expensive
Lead in times can be long
Requires additional fireproofing

Question 20

What are the advantages of a concrete frame?

Answer 20

Cheaper typically as a material cost
Good thermal and acoustic performance
Flexability in design when poured in-situ

Question 21

What are the disadvantages of a concrete frame?

Answer 21

Heavier so more foundation costs
Takes a lot longer than steel work

Question 22

How would you take off the strip foundations?

Answer 22

Structural Engineer’s drawings - indicative mark up
Excavation
Temp propping
Binding level
Rebar
Concrete
DPC
Vapour Control Barrier
Formwork

Question 23

How would you take off a mini pile?

Answer 23

Structural Engineer’s drawings - indicative mark up
Concrete
Excavation
Rebar
Formwork

Question 24

What is the build up for a SFS brick slip system

Answer 24

Brickslips
SFS
Insulation
Sheathing Board
Insulation
Vapour Control Barrier
Plasterboard

Question 25

What is the build up for a Pre Cast Concrete

Answer 25

PC brick slips, vapour barrier, insulation, support frame

Question 26

What were the advantages / disadvantages of the SFS vs the Pre Cast?

Answer 26

SFS was cheaper and lighter, meaning less foundation costs. It was a thicker build up so an overall marginal loss of NIA but was the preferred option.

Question 27

Explain the process you undertook to measure and cost both the concrete core and steel core options for the residential development project.

Gillingham House - Cores

Answer 27

The structural engineer had already produced a drawing of the concrete core options with the different wall thickness so i was able to measure and cost the concrete. For the steel, the engineer had provided sketches with beam types and bracing, so I was able to quantity and cost the steel per tonnage.

Question 28

Besides material costs, what other factors did you consider when comparing the concrete core and steel core options?

Answer 28

I also considered programme, so typically a steel frame would be quicker to erect, however, due to the step in levels going up the building, a lot more steel work had to be used to accommodate, in some areas very tricky. It was a lot simpler to pour the concrete in-situ. The programme would of effected the prelims as well.

Question 29

Gillingham House

Briefly talk me through how you gathered information for the core comparison

Answer 29

The structural engineer produced a design for the concrete core, which was included as part of their stage 3 pack. I measured the amount of concrete, rebar allownance and had a total for the core. They then did a mark up of a steel option

Question 30

Horatio’s House

How did you measure and cost the foundation?

Answer 30

I spoke to the lift supplier about required foundations and loadings and they propsoed a m2 area for the lift itself, and then applied a rate for a pad foundation

Question 31

Horatios garden

How did you measure the underpinning

Answer 31

I couldn’t measure as there was no design information, typically under NRM1 this would be measured as a linear meter but as I didn’t have a drawing to scale off, I itemised an allowance and applied a cost, using in house benchmarking

Question 32

Horatio’s garden

How did you present the infromation to the client

Answer 32

Explain process

Question 33

What is the difference between hot and cold rolled steel

Answer 33

The difference is in how they are processed. Hot rolled has been rolled at high temps, where as cold rolled is rolled at high temps then further process to cool

Question 34

What is a mini pile and how does it differ to traditional piled solution

Answer 34

It’s a pile with a much smaller diameter then a normal pile, making it a lot lighter and inexpensive.