Advances in the technology behind concrete mix design mean that specifiers of concrete for basement construction have a broader choice to achieve the desired end product to satisfy Euro Code requirements, but the weakness in any basement is the jointing. More joints are required in the construction to meet code requirements. However, this often conflicts with the contractor's needs to pour more extensive areas to align with pressures on the program.
Joints in construction need to be planned in advance of the works, and in these locations the jointing methods need to be arranged ahead of the structure of some sealing systems, meaning that any changes due to site activity often lead to solutions that slow construction.
Responsibility for the joint falls between the specifier and the contractor and possibly a specialist third party specifier. This specialist may only look at the joint specification or take the contract for the entire basement box providing a warranty for the whole of the basement box, based on a performance specification supplied by the specifier. At this stage, joints are still a variable based on construction sequence and are still reliant on workmanship.
The choice of sealing systems for forming joints is also varied, and there are many options available on the market, these range from simple reactive systems like hydrophilic strips or active systems such as PVC tapes or coated steel strips. The choice of injection hose systems may be selected in specialised forms of construction, such as tunnels. They can be used in basement construction where joints need to be formed against existing structures, but this is a specialised area of work and requires to the attendance of s specialist contractor to install and activate the system. Each sealing system has its own merits in the development of a joint. However, as is often the case, the choice of a particular sealing system is down to preference of the specification by the designer or contractor due to personal preference or even down to the cost. Notwithstanding the sealing systems will be the weakest point in any basement construction and the one that is often the least agreed by the team.
Cost is another factor in the decision-making process, with the unit cost/m, being the driver but stealth expenses and post working are not seen in the cost, in some cases a contingency is built into to cost to deal with leaks. Again these all have implications for program and project cost.
Sealing systems are therefore a fundamental part of any basement design and one that needs to be explored so that specification, site works and end use can all be understood by all in the design process.