How's it going LouthMan.
If you buy a site without planning you have 5 years as Carpenter said where the permission is valid from the time it is granted. Generally, before the planning consent is out of date, you need to have the project completed to the foundation/dpc stage to satisfy the local planning department. In some areas it could even be accepted with basic groundworks completed and trenches dug.
If a site already has a planning consent either outline or full in place, then you are already on a timeline and you need to be sure there is enough time remaining for you to submit your design if you want to apply for changes, wait for approval, find a builder and then get started.
If a site has outline planning permission, then you have to apply for full planning within 3 years of the date of issue. If you get full planning permission granted, then you do not get a further 5 years, but the 5 year term starts from the original outline permission granted date.
Build costs always have the piece of string analogy.
There are many many factors affecting the costing process. Site conditions, house design (4 walls or complex design), construction method, external finishes, internal finishes, windows, heating systems and on and on ...
If you are really looking for a finger in the air type approach then ring an architect or civil engineer in your area and ask what the current build cost per square foot is. These figures tend to reflect the lower to middle spec standard as applied by a general contractor, but it will give you a rough figure to work with. For direct labour knock off 25% to get an idea of what you could be looking at.
But any number of things could throw these estimates out. As soon as you start spec'ing luxury finishes in bathrooms, kitchens and floors, large amounts of glazing, high end electrical specs, slate and stone on your roof and walls etc, then your cost per sq ft starts to go up rapidly.
Another rough guide is the old one third/two thirds site value/construction costs. This is obviously just a real finger in the air approach.
If you are planning to build over 5 or 6 years, be careful to factor in labour and material cost rises into your budget.
Hope this helps.
AndyH
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