Defining the work behind a residential retrofit tender

We supported a consultant preparing builders’ quantities for energy-efficiency improvements to an existing residential block. The work combined insulation, replacement windows and doors, ventilation and renewable-energy measures. We developed the bill alongside a clarification record so that associated making-good work, specialist pricing points and unresolved design assumptions were visible to the tendering team.

Background

Retrofit measures do not sit neatly in isolation. A replacement window may also require insulated reveals, air sealing, plaster repairs and decoration; additional roof insulation may introduce ventilation or access requirements. Omitting those interfaces can leave a tender apparently complete while important work remains unpriced.

The available information did not define every detail of the existing building or the proposed finishes. The client needed a usable pricing document that represented the known scope while making the remaining assumptions clear.

Our approach

We agreed the measurement basis and output with the client before developing the bill. The commission called for builders’ quantities in Excel, with preliminaries and specialist work treated in accordance with the agreed scope. The clarification schedule provided a parallel record of questions, responses and the basis adopted.

We measured the retrofit elements from the available drawings and schedules, then examined the work needed around them. For windows and doors, that included the associated insulated linings, seals and making good. The descriptions helped connect the main replacement item with the work required to leave the opening complete.

The loft-insulation measurement distinguished the specified layers and their thicknesses. This mattered because the quantity of material across several layers is different from the physical area of the roof space. The bill retained that distinction rather than presenting one undifferentiated insulation allowance.

We also separated detailed measurement from specialist pricing. Cavity-wall insulation was represented with an identified area and a specialist pricing point, while the photovoltaic installation was allowed for as a defined item. Where the design did not provide a firm basis for measurement, the bill used an explicit allowance or clarification rather than implying precision.

Finishes required particular attention. We sought to establish whether redecoration applied only to disturbed areas or to whole rooms, and recorded the basis used where the information remained incomplete. Floor-finish allowances and potential lintel work were similarly made visible so that the tender could be read with an understanding of the risk being priced.

Further roof-related items were identified separately, including possible chimney work, repointing and ventilation at the eaves and verges. Keeping these additional items visible helped distinguish the principal retrofit measures from work that required a further scope decision.

Throughout the exercise, we retained the link between the measured item and the supporting clarification. This made the document more useful when a pricing question arose: the team could see what had been assumed and why, rather than having to reconstruct the reasoning from the quantity alone.

Outcome

The resulting builders’ quantities and clarification schedule gave the client a structured basis for obtaining and comparing prices. They represented both the principal energy-efficiency works and the associated activities that could otherwise be missed between trades.

Our contribution was to make the scope intelligible at the point of pricing. Defined quantities, specialist items and stated assumptions allowed the tendering team to understand what was included and where a further decision remained necessary.