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PHCPI Notes on changing specification or substituting house types

1. You will need to allow for a standard foundation design for your selected house type. If you are gathering data from sites which have a non-standard foundation design, the difference in cost should be calculated and added/omitted to/from the selected house type cost before calculating the change in cost (see Rule 2i).

2. Similar calculations should be made for other differences in specification between the selected house type design and the ones from which current data is being collected. This may be a temporary change in specification e.g. mahogany skirtings in lieu of softwood or to suit a particular location for planning reasons (see Rule 2ii), or a permanent change in specification e.g. a policy to change from timber windows to uPVC (see Rule 2iii). Both of these types of change in specification should be costed and appropriate adjustment made to the selected house type.

3. Where the selected house type is to be phased out, a new house type can be selected. If the new selected house type can be costed at the previous quarter’s mid-point, the change in cost can then be measured to the mid-point of the current quarter. (If the percentage change reported relates to a new house type please send details with this return). This then becomes the new selected standard house type.

Rules – each quarter

1.  Assuming the specification remains the same then:

(i) Cost selected (base) house type at mid-point of 1st quarter to be monitored (base cost).

(ii) From then on recalculate the cost at the mid-point of each quarter, and either state current cost or compare to the previous quarter’s cost and calculate percentage change.

2. Cost of changes in specification

(i) To adjust for non-standard foundations
Current cost of selected house type received from site but with non-standard foundation £50,000
Difference between standard and non-standard foundation -£3,000
(ii) Temporary change of specification e.g. mahogany skirting’s in lieu of softwood
Current cost of selected house type received from site but with mahogany skirting’s in lieu of softwood £47,250
Difference in cost between mahogany and softwood skirting’s -£250
(iii) Permanent change of specification e.g. uPVC windows in lieu of softwood
At the mid-point of a quarter when changing the specification, take the current cost of base house type and adjust for difference in specification at current costs. Current cost of base house type £47,000
uPVC windows in lieu of softwood £2,000
# This is now the cost to compare the next quarter's cost to (assuming the remainder of the specification remains the same)
* Compare to previous quarter's cost of base house type (assuming remainder of specification matches specification of base house type)

For further information and help

If you have any queries about how to allow for changes in specification, or any other matters, please contact Agnes Galeska on agaleska@bcis.co.uk or 020 7695 1515