Building a house in Pembrokeshire could cost developers an extra £30,000 as soon as the new owners set foot through the door.

The controversial proposal is part of the Pembrokeshire Coast National Park Authority’s draft affordable housing strategy.

Under the terms of the policy, anyone building a single property within the Park would be liable for the one-off payment towards low-cost housing.

The proposed single-property payment is one of a number of items included in the draft supplementary planning guidance which is due to be considered by Authority members today (Wednesday).

A Park Authority spokesman told the Western Telegraph: “If approval is granted, public consultation will begin next week. During this consultation, the Authority will welcome comments on the supplementary planning guidance including the method for calculating, and the level of, affordable housing contribution proposed.

“The guidance explains how the Pembrokeshire Coast National Park authority will apply its affordable housing policy, which includes the requirement for a financial contribution towards affordable housing, known as a commuted sum, on proposals for single homes.

“The sum being suggested in the consultation document is £30,000.

“Park Authority officers considered a variety of methods for calculating the payment, resulting in sums ranging from between £32,000 and £85,376 depending on the size of the property.

“Applicants for single dwellings will not be expected to pay other commuted sums such as those required of larger developments contributing towards the provision of facilities for education, libraries, open space, recycling and waste and sustainable transport.

“Proposals for self build affordable housing and rural enterprise dwellings will not be required to pay the contribution.

“The commuted sum may reduce the value of residential plots which are currently on the market for prices ranging from around £100,000 to £225,000.“ If approved, the consultation process will continue from early October until the beginning of January 2011.