THE cost of a Cowbridge school expansion has increased by more than £4m.

Vale of Glamorgan Council's cabinet has agreed to take the expansion of Ysgol Iolo Morgannwg to the next stage and to increase the project and programme costs by a further £4.25m taking the project budget to £22.31m.

From February to April 2023, the council consulted on proposals to expand Ysgol Iolo Morganwg from 210 places to 420 primary places with space for 96 part-time nursery places from September 2025.

In December 2023, Welsh Government approved the rolling strategic outline programme for the Sustainable Communities for Learning which included Ysgol Iolo Morganwg Primary School.

In November 2024, the council invited tenders for the construction of Ysgol Iolo Morganwg Primary School.

The construction cost issued within the tender document was £15m.

This was based on the estimated costs based on site conditions and current market.

The total budget approved for this scheme under the capital programme is £18.05m or £20.55m including the Claire Gardens land provided through Section 106.

In April 2025, the cabinet authorised emergency powers to accept the competitive tender for the construction of Ysgol Gymraeg Iolo Morganwg and appointment of successful contractor, Kier.

In September 2025, the council received approval from Welsh Government to proceed on the outline business case including the abnormal costs.

Kier have since provided further detail on the costs and detail of work packages that will need to be carried out as part of the scheme, totalling an additional £1.17m.

Kier Construction have identified a total of £2.17m for project abnormal costs, reflecting site-specific requirements that fall outside standard construction allowances.

These abnormal costs include measures such as heavy protection and piling, which are needed to deal with underlying ground conditions, enhanced storm drainage infrastructure to meet SAB (Sustainable Drainage Approval Body) requirements, the incorporation of raingardens as part of the sustainable drainage strategy and extensive cut and fill earthworks to achieve suitable site levels.

In November 2025, the contractor provided the second stage proposal for contract which includes the costs for all the work packages under the project.

The cabinet report said that the Sustainable Communities for Learning project team have worked closely with AECOM and contractors to carry out the checks and balances as part of a two-stage process, including assessment of market rates.

The contractor went out to market and the "not to exceed" figure exceeded the budget, totalling £20.75m.

Within Kier Construction's submitted construction costs, approximately £180,000 in potential savings have been identified and these will be explored in greater detail during the next stage of the project, the report said.

The main increases are as a result of the site conditions, wider market conditions, an increase in GIFA (gross internal floor area) and abnormal costs, the cabinet report says.

The capital funding currently allocated for Ysgol Iolo Morganwg is £20.55m and this is included in the council's capital rolling programme.

Speaking about the increase in cost, Cllr Rhiannon Birch who is the cabinet member for education, arts and the Welsh language said that costs have risen over the last few years for the usual range of reasons such as materials, labour and supplies.

Council leader Councillor Lis Burnett said as much as the current building is much loved within Cowbridge, being able to provide a new modern and expanded facility will be 'absolutely super' for them.

The post contract service works will conclude in the new year and cabinet has given its approval to proceed with the stage two contract with Kier.

It also approved an increase on the project and programme costs, to allow council to submit the full business case to Welsh Government by January 7.