The Tender AnalysisWhen you receive Subcontract tender documents, invariably they’ve got differences and it’s important to make sure you’re comparing Apples with Apples. Look out for these important cross-checks to make sure you’re comparing like-for-like proposals.
1. ControlsThere is a number of different control systems with UFH – if there is no specification the tenderer may not include controls, or their own controls – in this case there could be three different tiers of controls which can vary the price significantly.
2. Pump-setsHIU’s are becoming commonplace so it’s important to know the specification. Some have integral pumping and temperature blending capability, and some do not. This will have a significant price impact.
3. DesignMake sure you know what design is included, if it has been included at all. Heat-loss calculations are often not included, and the design should include the floor finishes being used within each room.
4. InstallSome contractors insist on a minimum quantity per visit – it is important that each contractor has priced the same guidelines – i.e. there is consistency between number of units / meterage available per visit.
5. CommissioningSome will include this – some will say it’s the plumber’s issue. Ensure it’s included as a separate return visit, and as with the install, there is consistency between number of units / meterage available per visit.
6. Screed TypeThe primary concern should be that the same type of screed has been allowed for and thereafter, has it been allowed for in all areas or has it just been included for in the heated areas.
Value EngineeringThis section identifies six simple, intelligent solutions to Value Engineer a Underfloor Heating package…
1. Thermal Insulation at Intermediate FloorsIntermediate Floors do not need to achieve a U-Value because they count as party floors. Despite this, in many cases, Architects will specify the use of Polyurethane rigid foam (or PUR Insulation for short) as a high-performance insulating material. Please note you need to comply with BS-EN:1264.4, some insulation is required below UFH but typically much less than ground facing floors. With some design calculations on the U-Values of the building, more often than not, this high-performance (and high-cost) insulation can be calculated/designed out and replaced with more economical Expanded Polystyrene (EPS) insulation that still meets the performance requirements.
2. Thermal Insulation at Lower/Ground FloorsOn the lower floors where you have a block and beam floor, the Design team will often have included for a single layer (often 100mm) of high performing PUR insulation. An alternative is to use two layers (2x 100mm) of lower U-Value Insulation such as Expanded Polystyrene insulation (EPS). Two layers of this insulation are equivalent in terms of performance of 100mm of the superior PUR insulation however far more economical.
3. AcousticsOn larger Apartment blocks party floors with acoustic requirements are often over-specified and a day or two of focus with an Acoustic Engineer, can highlight the over specification in Acoustic Insulation. Invest a day to put together an Acoustic Report showing performance levels of the specification are met with a reduced thickness insulation and submit this together with our design for approval to take the saving in reduced material purchase.
Programming the Site WorksUnderfloor Heating is a package of works that fall on the critical path of the project and just before Practical Completion. Despite this, it is sometimes seen as a minor package of works and therefore, little attention is paid to them. Don’t make this mistake and follow these six tips for a snag free handover.
1. DesignAlways provide the UFH contractor with the most up to date information to minimise the volume of drawing revisions. From the outset, provide the following to enable an economical design process:
- SAP calcs
- Manifold positions (allowing enough space)
- U- values for walls, roof, windows and other fabric materials
- Details of Floor finishes and layouts marked with kitchen units and other fixed furniture – areas which need not be heated.
- Elevation and section drawings which indicate the ceiling heights and glazing so heat losses can be calculated.