All Engineers are equal, but some are more equal than others
Why you should talk to DFP first
The misquotation above is the famous line from George Orwell’s Animal Farm. It's actually very true. It is well known that if you give two Engineers a problem to solve you will get two solutions. The service you receive from different Engineers will not be the same and the overall cost is unlikely to be the same.
When clients carry out a project they know they need an architect and a contractor but the rest of the design team is often considered an unnecessary, unwanted additional cost. With this in mind clients often ask us for competitive tenders for services such as Structural Engineering and think by accepting the cheapest they are getting the best deal. How wrong can they be!
When paying less can cost you more
If an Engineer is on a restricted fee there is no scope to optimise the scheme and the Engineer has to pass as much work as possible onto the contractor. Getting a design through Building Regulation approval and providing a scheme that can easily and economically be built are two very different things.
With a technical solution most clients don't know if they are getting a cost effective design. A beam spanning a room may or may not be the most economic solution. On a reduced fee, loading calculations may be (probably will be) over estimated and the first beam, big enough to do the job is used. There is insuffevient fee available to check alternative layouts or materials.
Why you should choose David French Partnership
With housing work it's easy to design beams and padstones with scant regard to the impact on the property or buildability. You can leave the specification of trussed rafters, lintels and precast flooring to the relevant suppliers. Following this approach can result in significant issues and costs at the construction stage. The trussed rafter roof has to be detailed in a way that has been allowed for in the design stage. If this is not considered as part of the engineering design the loads from the trusses may end up being applied to areas which were not allowed for. The ‘Free Lintel Design’ offered by lintel manufacturers often do not allow for heavy point loads from trusses and beams. Pre-cast floors may be positioned on walls that are not fully load-bearing and so on.
It is far better for the Engineer to take a holistic approach to the design to get a good solution at the design stage rather than trying to ‘make it work’ later.
To tender or not to tender?
It seems a regular occurrence these days to tender for engineering services. On one occasion we had been asked by an architect to tender for engineering services. We asked why he required engineers to tender for professional services and the response was “to get the best value for our client.” We then asked him if there were cheaper architectsthan him... and if there are why is he not recommending using a cheaper architect and giving even better value to the client? The reply was “… but we are good at what we do and the client wants our expertise.” What that Architect did not realise is that exactly the same argument can be applied to our engineering. We are good at what we do and our expertise will benefit you by ensuring a more economic, well planned and detailed end product.
The old adage of ‘you get what you pay for’ occurs in engineering every bit as much as it does elsewhere. The potential problems with ‘cheap’ engineering are best illustrated by a few case studies:
We have a client we have worked for many years who kept complaining that our fees were too high. We tried to explain to him that to do his jobs efficiently and economically took time plus he expected a far higher level of input than just the engineering.
We tendered on two large executive homes each worth close to £2M and were told our fees were too high. We explained our fees, but he opted to go elsewhere. We said we were sorry to lose him but could not compete with the lower fee offered by another engineer. It was about 50% of what we had quoted. We didn't think any engineer could do the job he expected for that fee and offered to check the other engineer’s design, at our expense, to see if he was getting value for money.
Some time later he contacted us and asked us to do the design check and we were appalled at what had been done.
- The other engineer had the ground bearing pressure wrong.
- The trees were identified as the incorrect species resulting in excessive foundation depths.
- The foundations were at tender stage but the location of the properties had not been finalized.
- All the foundations were over-sized. In one area the foundations were 3m wide and in another area they were 2m wide. The site had a clay subsoil with trees so the foundations were deep With a clay subsoil and trees as well as wide the foundations were deep resulting in huge concrete costs.
- Two almost identically loaded foundations had one 1.4m wide and the other 0.75m wide when they should have been the same size. They needed to be only 0.45m wide!
- The foundations and walls were designed to tender stage but the roof, which contained attic rooms, had not been designed and was shown spanning the width of the building and not the shorter span in the other direction.
Had the job remained as designed it would have wasted a huge amount of the client's money.
The client dismissed the other engineers and appointed DFP at the rates we had originally quoted. We re-designed the project saving the client a significant amount of money.
A project we worked on was designed by a small engineering company. The steel contractor had already been appointed. When a new developer took over the project we were asked to check the scheme and see it through to completion. On checking the original design, the steelwork to the basement car park was found to be very simply, and inefficiently designed resulting in more steel being specified than was necessary.
We redesigned the steel and reduced the tonnage from 108.5 tonnes to 79.1 tonnes. This saved 29.4 tonnes of steel which today is worth around £50,000. This saving on its own was far more than our fee for the whole job.
We were working for a steel fabricator designing the steelwork connections. In days gone by all critical connections were designed by the engineer. With the squeeze on fees, connections are now expected to be sorted out by the steelwork fabricator.
The engineer specified the forces to be used for connection design but the forces shown were large. This made the connections very heavy, complicated and costly. We asked the engineer whether the moment and shear forces specified occurred at the same time in the same loading situation and, if not, could we have the forces for the different load situations. The engineer said they did not have the fee available to provide this extra information and told us to design on the forces shown. The client ended up paying more for the steelwork than necessary, purely because they thought they would save money by using a cut-price engineer.
We quoted to do the engineering on a large, prestige house extension and were told our price was too high, so the job went to another engineer. Later we were contacted by the builder who wanted some calculations to justify some changes he had made during the build. The original engineer would only do the extra calculations if the contractor paid him a high fee. The contractor came to us knowing we have a reasonable fee structure.
To do the extra calculations we were provided with the scheme details as prepared by the other engineer. It was immediately apparent that it was significantly over-designed. In one area where there was a long span and the rafters specified for this area were 75x225 C24 at 400 centres. A DFP design check showed these were bigger than necessary even for the long span. The same rafters had been specified for the whole job. This probably cost the client £1,000 or more for large expensive timbers, where small cheap sections would have been totally adequate.
Also, as shown above, all the engineer had done was to mark up over the architect’s drawings the engineering providing no details of how beams intersected or where they were located. All this was left to the contractor to sort out which resulted in projecting beams which could have been hidden etc.
I did not check the scheme fully as it was already built but there were other areas where the design appeared uneconomic and the cost to the client was much higher than necessary – almost certainly more than the original design fee DFP had quoted!
We tendered for a large project and although our tender was in fact the lowest the client opted to use an engineer they had used before. Some time later the client came back to us and paid us to check the design the other engineer had prepared as the cost of the structure was much higher than he had expected. When we did the design check on a large area of slab we found that the engineer had designed a heavily loaded area on a computer program.
Whether he misunderstood the computer output or chose the approach he took I don't know. He had worked out the area of reinforcement needed based on the heaviest loads even though the loads occurred in different directions. He then added on a margin for safety and ran this amount of steel in both directions more than doubling the cost of steel needed.
As well as this over-design, the engineer then specified the same amount of steel over the whole slab even though most of it was nominally loaded. This resulted in a colossal amount of wasted reinforcement and huge extra cost.
- Subsidence or Settlement? Either way there's no need to panic!
- The Party Wall etc Act 1996
- Construction (Design and Management) Regulations 2007
- All Engineers are equal, but some are more equal than others
- Computer Aided Design