Our architect wants to add a stage of exploratory works before the plans for our church repairs are completed. Would you explain what this is about, as it seems to us that this just adds another level of cost?

REPAIR works on old buildings can hide surprises for the professional team and, eventually, the builder; so exploratory works are often the means of reducing the risk of discovering an issue with expensive ramifications.

When the issue is identified before the contractor is on site, there is normally a financial saving: the time the builders are delayed by waiting for the architect to arrive to assess the issue; the problems of time and cost of getting in materials to repair something unexpected; any specialists who will need to be consulted; and so on.

On roofs, there may be several issues: rot in the underlying wooden trusses; damaged rainwater goods at high level; the extent to which slate may be reused, and how much must be new; erosion present in high-level stone; and many more. If your works include ground-level repair, then exploration under the floor or into the earth outside may identify archaeological issues, such as burials, or earlier works - drains that are so damaged that there is no pipe run to repair.

Almost always, the preparatory exploration will uncover a sample area where repair or new works are to happen, and effectively reduce the risk of the unknown and costly intervention.

I have, more than once, encountered holes dug in church floors, small areas of slate/tile removal, and, more recently, an upfront excavation across the churchyard for drainage pipes - the latter to reduce the risk of archaeological issues that may delay the main works when the contractors are on site. When workers are on site, their wages are paid by you, even when they can make no progress until an expert comes to site.

It is most likely that your architect knows a builder who will do the exploratory works at reasonable cost, knowing that this does not imply that when you go out to tender the builder will get preferential treatment.

Do ask the architect, with the builder, to give you an estimate, up front, for the exploratory works, so that you know what you are committed to. You can then identify how this cuts into the sums that you have saved for the main works stage.

For larger repair projects, as well as new works, it is advisable to have your quantity surveyor look over the exploratory works and resultant reports with you. He or she will be able to advise you on cost implications that may be outside your original indicative budget, or may have been hidden in the contingency the budget allowed.

Send your questions and comments to maggiedurran@virginmedia.com.