The following examples have been prepared to illustrate how the additional cost of the changes in construction practice and the introduction of pre-completion testing will affect small sites:
Example 1. A small site with one pair of semi-detached dwelling houses.
Requires 1 set of tests (walls only)
2 airborne tests @ £240 per test = £480
Thus cost of tests per dwelling is 480÷2 = £240
Increased cost of separating construction per dwelling = £50
Increased cost of internal walls per dwelling = £8
Increased cost of internal floors per dwelling = £285
Total increased cost is £583 per dwelling
For dwelling houses, the increased costs are greatest on small sites like this.
Example 2. A site with 2 terraces each having 5 dwelling houses.
Requires 1 set of tests (walls only)
2 airborne tests @ £240 per test = £480
Thus cost of tests per dwelling is 480÷10 = £48
Increased cost of separating construction per dwelling = £50
Increased cost of internal walls per dwelling = £8
Increased cost of internal floors per dwelling = £285
Total increased cost is £391 per dwelling
Example 3. A site with 1 terrace of 5 dwelling houses and 3 pairs of semi-detached dwellings.
Requires 2 sets of tests (walls only)
4 airborne tests @ £240 per test = £960
Thus cost of tests per dwelling is 960÷11 = £87
Increased cost of separating construction per dwelling = £50
Increased cost of internal walls per dwelling = £8
Increased cost of internal floors per dwelling = £285
Total increased cost is £430 per dwelling
Example 4. A small site with 1 block of flats having 1 ground floor flat and 1 first floor flat.
Requires 1 set of tests (floors only)
2 airborne tests @ £240 per test = £480
2 impact tests @ £300 per test = £600
Thus cost of tests per dwelling is 1080÷2 = £540
Increased cost of separating construction per dwelling = £750
Increased cost of internal walls per dwelling = £8
Increased cost of internal floors per dwelling = £0
Total increased cost is £1298 per dwelling
For flats, the increased costs are greatest for small blocks of flats like this.
Example 5. A site with 5 blocks of flats each block having 1 ground floor flat and 1 first floor flat.
Requires 1 set of tests (floors only)
2 airborne tests @ £240 per test = £480
2 impact tests @ £300 per test = £600
Thus cost of tests per dwelling is 1080÷10 = £108
Increased cost of separating construction per dwelling = £750
Increased cost of internal walls per dwelling = £8
Increased cost of internal floors per dwelling = £0
Total increased cost is £866 per dwelling
Example 6. A site with 1 block of flats having 2 ground floor flats and 2 first floor flats.
Requires 1 set of tests (walls and floors)
4 airborne tests @ £165 per test = £660
2 impact tests @ £300 per test = £600
Thus cost of tests per dwelling is 1260÷4 = £315
Increased cost of separating construction per dwelling = £750
Increased cost of internal walls per dwelling = £8
Increased cost of internal floors per dwelling = £0
Total increased cost is £1073 per dwelling
The following example is given to illustrate typical costs with flats tested at the rate of 1 set of tests per 10 units and with a reduction in costs where there are multiple tests in the same block of flats.
Example 7. A site with 1 block of flats containing 78 flats.
Requires 8 sets of tests (walls and floors)
32 airborne tests @ £105 per test = £3360
16 impact tests @ £200 per test = £3200
Thus cost of tests per dwelling is 6560÷78 = £84
Increased cost of separating construction per dwelling = £750
Increased cost of internal walls per dwelling = £8
Increased cost of internal floors per dwelling = £0
Total increased cost is £842 per dwelling
There is considerable concern in the social housing sector at the number of neighbour disputes that relate to noise complaints and raising sound insulation standards has been an issue in the sector for some time.
In the example calculations shown above, the construction related compliance cost has been estimated by calculating the cost of moving from the current range of common constructions to the anticipated new situation. In order to ensure reasonable standards of sound insulation several registered social landlords already tend to use better performing constructions than many speculative small builders. Also, the cost of sound insulation testing has been shown as an additional cost, although many of the larger social landlords already conduct pre-completion testing on their sites.
Because of these issues it is thought likely that the increase in costs for the social housing sector may well be smaller than for speculative builders. It has been estimated, and agreed with the Housing Corporation, that the sector will lose between 70 and 100 dwelling units per annum (0.4% -0.6% of the number of new units approved by the Housing Corporation in 2001/02). Alternatively, the sector will require an additional public subsidy of approximately £5.5 million a year at 2001/02 prices in order to retain current levels of development.
As Housing Associations already build to a fairly high density it is unlikely that this estimate will be affected significantly by the PPG3 policy.
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