Insurer BLP has come up with a digital system for policing building projects and spotting problems before they happen

How do you define quality in a new building? Once you have, how do you measure it? And how do you decide if one building will be more robust than another? It’s a tricky problem not made any easier by the fact that buildings – unlike cars or washing machines – aren’t built from a kit of parts in a controlled environment.

One approach favoured by defect insurer BLP is to check everything that happens – or almost everything. The company has come up with a slick new software tool that it believes could massively cut down on the things that compromise the quality of a building, and it could have a wider impact on the industry, too.

The tool is called CACTUS, which stands for computerised audit claims tracking and underwriting system. It has been 18 years in the making and its purpose is to enable BLP to manage the risk of the buildings it insures. “We take the view that what actually matters is what’s being built,” says Paul Wornell, technical consultant of BLP and the man behind the software. “Forget who the builder is, let’s focus on the building: is it designed properly, does it follow good practice, and is it being put together properly?”

What CACTUS is not is a set of standards that the construction team must follow like a rule book. What the firm is looking for is a building that conforms to existing building standards, such as Building Regulations, British Standards, codes of practice and so on.

Over the past two decades BLP has built up a database of forensic detail on what goes wrong with buildings. This enables it to focus on the things that could ultimately result in a claim. “Our focus is firstly on the high-frequency high remedial cost items followed by the low-frequency high remedial cost items, high frequency medium cost items and so on,” says Wornell. You get the picture. It means it can get these things on to a checklist.

All this is historic data. What the firm also keeps tabs on are the emerging construction techniques and new products that could result in claims in the future. These could on the face of it be harmless-looking trends such as the uptake of underfloor heating and the use of plastic pipework, to more radical initiatives such as insulated concrete formwork.

And then there are other changes, such as those in legislation, that can have knock-on effects, as well as trends such as the resurgence of basements for private housing, built by an industry not used to constructing them.

Yet all this knowledge is worthless without an effective way of managing it, and this is where CACTUS comes in. The software is used as the basis of a three-stage technical review beginning with the design.

From the construction drawings, one of BLP’s design checkers is able to create a picture of the building and its key elements. Typically for a domestic building this would include foundations, basement, walls, floors, roof, windows, doors and drainage. What this does is act as a filtering mechanism and generate a manageable list of subject headings against which the checking process can begin. The first is what the design needs to be to meet best practice. “So if, for example, it’s talking about the roofing membrane, by ticking that you are basically saying it is fit for purpose,” says Wornell. Below this are further statements with variations on this preferred option ending with a final statement that says whether the designer has met the required standard.

Supporting documents next to these statements mean the checker has all the information about what is best practice at their fingertips. These encapsulate and distil what is known. “We’ve had to read through umpteen standards to get there but it is there,” says Wornell. This process flags up any areas of concern and also provides an audit trail of all the steps taken.

The second stage of the process is a component and materials check. BLP provides cover for materials and components, and CACTUS has been developed so that the component life and essential maintenance requirements can be considered.

The tricky bit, of course, is when things move to site. But this is where the tool comes into its own. BLP has invested in 20 robust tablet PCs that its checkers can take to a site to measure how things are being done at the workface. “It’s been shown that if an inspector goes out on site their performance is significantly increased if they have a checklist. Even experienced people don’t see all the problems,” says Wornell.

CACTUS is the ultimate checklist. The idea is to time inspections to coincide with key stages of the building and increase the frequency if it is unusually complex or large.

Wornell gives foundations as an example. One of the subjects highlighted by the design check might be a weak underlying stratum. “So we ask our site inspector to respond to that. They’ll have a set of statements asking whether it’s true, untrue, unseen or they can make an observation about it,” says Wornell. All of this makes up the audit trail.

Cynics might see all this as a way of compiling exclusion clauses, and going through the process does influence the premiums. But could such a tool have other uses?

One possible application for the system might be to improve the functioning of building control and increase compliance standards. After all, the tool is intended to manage risks and although building control officers are not responsible for quality control on site, a system that provides an auditable checklist approach could address accusations of inconsistency and poor compliance and reporting.

The five most common defects in housing

Design stage

  1. Soakaways designed without sufficient capacity
  2. Inadequate upstands for flat roofs
  3. Fixing design for balustrades not robust enough
  4. Foundations not designed adequately, particularly in clay soils where trees have been removed, which can lead to differential settlement
  5. Not enough movement joints in masonry
On site
  1. Not enough fixings for roof tiles
  2. Inadequate provision for differential movement to timber frame walls with masonry cladding
  3. Breaches in fire stopping
  4. Beams supported on masonry walls not having adequate localised strengthening at the bearings to distribute the load onto the wall
  5. Size of electrical cables not increased when they are run within insulation in walls and roofs, resulting in overheating