Analysis

Testing the BIM waters in social housing

23 September 2015 | By Will Mann

The BIM capability among our suppliers varies enormously from package to package. Give the model to steel fabricators and they're quite happy. Decorators haven’t got a clue.– Gary Barton, Durkan

Use of BIM in social housing has been limited to date, but housing contractor Durkan plans to be an early adopter of the technology. Technical manager Gary Barton explains why.

Why are you starting to use BIM in a sector that has not used the technology widely?

Social housing has been slow to embrace BIM because, understandably, clients first want to see the benefits from investing time and money. But the wider construction industry is now showcasing what is possible through BIM. We feel it won’t be long before housing clients come to us with a BIM requirement, and we wanted to try it ourselves first so we can be prepared. If government agencies start demanding BIM on new developments, we’ll be in pole position.

New build social housing is seen as highly repeatable, can BIM bring many efficiencies?

There is that perception. Some social housing contractors have been through a rationalisation process and developed their own “house types” where the construction process is repeatable and highly efficient. BIM may not be for them.

But in our market, all the jobs tend to be bespoke. We predominantly build in London, and the plots are always varying sizes and shapes. Each planning authority wants something different from the one next door. The client wants to maximise units on each site. The Lifetime Homes standard provides a design guide, and in theory every client and designer could use that, but in reality they do not. So for those reasons, very rarely do we carry over a design from one project to another. And that’s why we think BIM can help us.

Where do you see advantages in using BIM?

So far we have found it helpful for driving out mistakes in the design process that would normally only be found on site. We work primarily with concrete frames and once the frame is complete, alterations can be quite costly. For example, on a project at Hiltons Wharf in Deptford, an eight-storey mixed development of affordable and apartments for sale, we discovered the boiler flue runs were clashing with other services. We were able to recast the runs in the downstand beams, avoiding the rebar, which would have been much trickier if we were drilling them on site.

BIM has also helped with design of the ground engineering. In London, ground conditions can vary from site to site. At Hiltons Wharf, the site was on the river. We had to cut the retaining wall of the river bank and tie it in with our foundations, and using BIM’s 3D modelling capability was crucial to achieving this.

Have you measured the benefits BIM is giving the company?

It’s early days, but we can certainly say we are building concrete frames quicker than is typical, and receiving far fewer RFIs [requests for information].

What have been your biggest challenges in using BIM to date?

Bringing our supply chain up to speed – the BIM capability among our suppliers varies enormously from package to package. Give the model to steel fabricators and they’re quite happy. Decorators haven’t got a clue.

Steel is one of the more advanced trades because they have been using CAD technology for years. On Hiltons Wharf, the block was a concrete frame apart from the top two storeys which were duplex apartments made from steel. We could take a digital design for these storeys from the manufacturer (Metsec) and integrate it with our BIM model for the whole building. That worked really smoothly.

With concrete, the reinforced frame contractors are not at that level. But they could see on Hiltons Wharf the advantages of the BIM model, for example, being able to click on individual beams to see the volume of concrete and reinforcement required.

Do you involve the client’s FM team in the BIM process?

Our goal, when we complete a project, is to have a BIM model with asset data right down to serial numbers and unit costs, which we can hand over to the FM team so their job of finding replacement parts is much easier.

But the reality is the clients don’t have their heads round this yet. They already have tens of thousands of buildings and their own FM system for managing them. In theory, you can take a COBie file from BIM software and use that data with FM software. But a COBie file is just a mass of data on a spreadsheet and to someone who works in FM with limited knowledge of BIM, doing that is going to be challenging. 

That’s why we have started this process with our own development team [Durkan Estates]. We made a group level decision that BIM could potentially give us benefits in design, construction and FM. Once we understand how BIM benefits our Estates business, we will be better positioned to explain those benefits to our external clients.

The advantages for FM could be huge. If you take plant rooms, this is a critical area for FM teams, but they can be designed far more smoothly digitally than on paper. And when maintenance is required, it is far easier to find a replacement part by calling it up on a digital model rather than trawling through a lever arch file to find it.

How widely will Durkan be using BIM in the future?

In a year to two years, we want the majority of our projects to be designed in BIM. If nothing else, it encourages collaboration, because when you use BIM, you can’t build the thing without everyone talking to each other. With paper drawings, consultants can get away with doing their own thing.

We think the biggest advantages will be for more complex schemes with big plant rooms and communal services distribution. There is no benefit using BIM for a two-storey house. The biggest savings could be achieved by getting on board with clients before planning, so we can influence the design of the scheme – “optioneering”.