Different types of maps - Surveying

Maps used for measuring land and building boundaries come in three types outlined below. The only way to ensure your property is mapped with reliable is an onsite survey from professional surveys such as PCA.

Ordnance Survey Ireland (OSI)-Limitations

OSI maps are fit for purpose as national mapping. However, they are not intended be relied on for a high level of accuracy. Accoring to the OSI their maps are accurate only up to:

Property Registration Authority (PRA)

  • The PRA map is based OSI mapping and may miss detail missed by the OSI.
  • The PRA map is supposed to represent legal proprties not necessarily physical features. The OS maps physical features.
  • The PRA may now moves legal boundaries onto OSI physical detail. So if the OSI records a boundary as the centre line of a row of trees, not wall hidden beneath the trees, the new PRA map can also show the boundary as the centre line of a row of trees and not the wall or fence previously registered.
  • For this reason, surveyors are recently and increasingly encountering problems where the new PRA mapping has changed the legal title boundary to an incorrect physical boundary feature.
  • The PRA map "identifies property, not boundaries" for more information see Property Registration Authority (PRA).

    The following is taken from Land Registry FAQ 10 :

    I have a dispute with my neighbour over where the boundary lies. Can you tell me who is right?

    No. The Land Registry map is an index map and identifies property, not boundaries. Therefore, we are not in a position to advise.

    Professional Boundary surveyors

    Prendergast WP, Flynn M, Corrigan P, Sweeny BF, Martin Á, and Moran P 2008,

    Green Paper Proposing Reform of Boundary Surveys in Ireland, Irish Institution of Surveyors, Dublin, p. 109.