I am advised that it would not be appropriate to prescribe a mandatory limit on the gradient of the driveway to a house in the building regulations. The gradient of the driveway must be decided by the designer or builder taking into account all the circumstances, including the topography of the specific site and the needs of the potential purchaser or tenant. It would not, therefore, be possible to lay down a hard and fast maximum gradient rule which would be appropriate in all cases.
However, I agree it is desirable to have some general guidance in this area. My Department will shortly issue an updated edition of the booklet "Recommendations for Site Development Works for Housing Areas" which will include a recommendation on gradients for driveways. My Department accepts there are many sites where compliance with any general recommendation may not be possible if housing development is to be permitted.