Will digitalisation scupper slapdash builders?

My self build created a plan factory. First there were the plans for the planning application. They consisted of front and rear elevations, side elevations, ground floor and site plans, first and second floor plans and sections.

When the proposal was rejected, a revised version was produced – along with the same number of plans. This was also rejected.

Plans for submission number three were so deliberately outrageous only a dedicated survivalist intent on recreating Hitler’s bunker in the heart of suburbia would have approved.

Naturally, my local planning department didn’t. However, they did, eventually, accept the original submission, with minor variations. Of course, this involved another set of plans. And all before the fully detailed plans, showing how the house would actually be built, were drawn up and submitted to Building Control.

Twenty years on all that remains of this impressive architectural library is a single set of ground floor plans, heavily seamed from folding and re-folding on site, scribbled with largely incomprehensible notes and garnished with copious coffee and concrete stains.

Should that matter? Well, at the time, not at all. Those plans were a badge of honour, testifying to the remarkable fact that they had actually resulted in a shiny new residence

Even better, they were proof that our two-year construction marathon was, to our ecstatic relief, finally over.

Except, of course, it wasn’t. Few self builds come to a defined end. Once the completion certificate is issued and the builders have gone, there’s typically decoration, furnishing, deciphering the heating system and the garden to tackle. All too soon it begins to merge with ongoing maintenance and, in time, remodelling, extending and major repairs. And that’s where problems can start.

In our case it was prompted by a decision to convert the underused ground floor into a separate one-bedroom flat. This involved sealing off the stairs in a cupboard (in case of a later change of mind), replacing the garage door with a wall and window and separating off the electrical and heating systems.

Local tradespeople accomplished all this with relative ease. Until we came to the mains water supply. The mains pipe entered in what had previously been a corner of the garage, so fitting an offshoot for the ground floor alone was easy. Now all we needed were two new meters: one for the ground-floor flat, a second for the floors above. No problem with the ground floor. Lots with above.

The reason was simple. No one knew where the supply pipe entered the upper floors. After the stopcock in the former garage it simply disappeared into the adjacent stud wall. Examining the wall in the kitchen above was all but impossible. It was covered in built-in floor and wall units, one of which contained the central heating boiler.

No clues

Delving in cupboards provided no clues. The only visible pipework, supplying the sink taps on an adjacent wall, vanished into plasterboard.

Perhaps the plumber who’d fitted it would remember, but he’d been subcontracted by our main contractor and we had no record of his name. He certainly hadn’t left us any diagrams of the plumbing layout. And we couldn’t check with the main contractor because he’d since gone out of business.

Our only recourse was to dismantle the built-in units and possibly part of the floor, if not the wall behind: not a great idea with a timber frame.

Now the obvious way to avoid situations like this is to compile a comprehensive build diary, taking pictures or videos throughout your project, keeping all plans, carefully marking any variations on them and eventually creating an all-inclusive house manual which will not only be invaluable to you but also to future occupiers. Well, good luck with that. Unless you’re on site all day, every day, you can’t be entirely sure you’ve noted everything that might be important later. But then neither will anyone else, especially the professionals.

The building inspector will only pay flying visits at key stages, similarly your architect, if he or she makes site visits. Your contractor’s main concern is completing the project to your satisfaction, which might not be his, while subcontractors are chiefly concerned with finishing this project before the next starts. In other words: bish, bosh, move on.

So how do you counter this? One way is to hire a trusted project manager who can both check and explain every stage, while giving you time to maintain a build diary.

But there’s another way on the horizon, one that big construction is increasingly taking. It’s called BIM, which stands for building information modelling. Essentially, it means digitalising the entire construction process. In other words, designers, clients, main contractors, subcontractors and suppliers all share the same vision of the completed building – usually digitalised in the form of three-dimensional architectural drawings.

Any discrepancies or inconsistencies in the design are then immediately obvious, subcontractors know exactly where and where not to drill, and efficiency, quality and cost control all improve dramatically. And, of course, after completion that extraordinarily complete description of the building remains on record, ready to be consulted whenever needed.

So will BIM ever work for a self build? Current pressures are pushing housebuilding towards more and more prefabrication, which potentially provides a much more BIM-friendly environment.

But if it depends on a mud-soaked ground worker pausing at the end of a drainage trench to input its precise direction and dimensions into a tablet… I’d tend to give it a generation or two.

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