When it comes to building new houses or extensions, Irish people often don't see the need for construction drawings or haven't in the past. I've experienced it myself in the past, where people go off and get prices or engage building contractors based on information contained on "planning permission only" drawings.
What's the difference. Everything really, planning drawings are not required to contain detailed information on construction, other than to convey the basic design and outline finishes, overall dimensions, location and position of opening etc. Atypical drawing which I would include as part of a planning submission is indicted below
Construction drawings by their nature should contain sufficient information for someone to build the dwelling/building from. The information contained on the drawings should enable works be undertaken in compliance with the building regulations; be it thickness or position of insulation, opening sections to windows, or size of the roof timbers or whatever. Furthermore, construction drawings allow the designer, to convey how s/he wishes specific element of the building be finished, eave overhangs, downpipe poisitions or even finishes. While much of the information relating to building regulations is standard (or was ), as most regulations don't regularly change, except for Part L, relating toConservation of Fuel and Energy (insulation in otherwords), many building contractors are not always familiar with other amenements.
Why not provide construction drawings at planning application stage? Well it can be done, however in terms of providing value for a client, its not the best route; in many instances, the house or development granted permission, varies from that applied for, often requiring amendments during the planning process, be it minor amendments or sometimes a substantial redesign or in cases the development has been refused permission.Furthermore planning authorities do not access development in terms of compliance with building regulations, their is to access compliance with the planning policy.
Of course one benefit of construction drawings, it it allows a building/dwelling be accurately priced, when prepared in conjunction with a relevant specification. The less information a building contractor has, the more assumptions s/he makes and the greater chance what s/he delivers is not what the client had in mind.