We’re giving project management support on one of our projects at the moment, and we’ve agreed to do this because of the nature of the project, namely the redesign and updating of a 1970’s house. In addition to the usual requirements for a project of this type, such as additional ensuites, and lots of electrical wiring, the client wants underfloor heating throughout, and mechanical whole house ventilation with heat recovery. Electrical wiring for the LED perimeter lighting and the controls, alarms, sensors and a modern standard in electrical sockets is, of course, the east bit despite the quantity, but getting the larger pipework hidden in the floors without cutting too much of the floor joists away is really difficult. Unlike the waste pipes carrying toilets and other waste water, the ventilation pipes can bend and flex their way around the building to some extent, although it has to be borne in mind that every bend will decrease the system’s efficacy.
Open lattice joists are really helpful.
With this type of project, it is absolutely essential to have a strategy for the incorporation of all these services and it may have implications on the design of the building envelope. With new buildings or extensions to old buildings, you can opt for lattice type floor joists. These are a real boon as they allow all of the trades to install their services without cutting holes in the floor joists. When it comes to the existing floors, some way of distributing these services tangentially to the direction of the joists can be really difficult. To facilitate the distribution of these services at right angles to the joists, a lean-to roofspace over a ground floor extension is a great help and, so for a workable solution to the installation of the services, even the design process of the building externally may have to be brought into play. Without this strategy and an overall design, a project can grind to a halt until some desperate measure is conjured up which will probably impact upon the interior design such as ducting and drop ceilings. Worse still, a thoughtless client or project manager will bully the tradesman to find an expedient solution (expedient for the tradesman that is) and large chunks of structurally significant floor joists will be cut out.
A lean to roof space is really useful.
Having worked out the general route these services will take you then have to ensure that the services go in the right order because clearly, some services are less flexible than others. The pipes taking wastewater should run in straight lines and of course to an acceptable fall, otherwise, your pipes will block and sanitary ware will gurgle and release bad smells. Then the pipes carrying supply and return air should be installed. These can bend to some extent and go up and down but because of their size, they are not always easy to incorporate. Lastly, much to the annoyance of the electrician, the electrics are last as the wiring can go up and down and can, if necessary, judiciously be fed through small holes in the floor joists. Even so, there are rules of thumb about where you can drill holes in floor joists and a good electrician will follow these. Having said this, some clients such as housing associations will not allow any holes to be cut in structural joists and for good reason. Done carefully, it generally is accepted by most Building Inspectors, though.
Waste pipes have to take priority.
Part of the job of the Project Manager in such cases is to ensure that the strategy is adhered to, that the sequence of the trades is in the right order and to adjudicate in the squabbles between the trades and decide what trade has priority. This is one of the reasons we can’t take on many projects on as Project Managers, they’re very time-consuming and we have to charge accordingly. More than one client has said to me that they wish they had asked us to project manage their project as the overspend caused by the resolution of these difficulties on-site can be very very significant in terms of time and money.