Chapter Eight Dampness, Condensation and Mould
Introduction to Dampness, Condensation, and Mould
8.1 While not a primary objective of the CHP, tackling dampness, condensation, and mould in Scottish housing has been a major priority in Scotland for over a decade. The general solution for tackling condensation and mould is to increase the heating used within the home, to increase the insulation of the dwelling, and to improve the ventilation. Thus, installing central heating and insulation under the CHP improvements should help reduce the extent of dampness and mould growth problems where they are condensation-related.
Dampness and Condensation
8.2 Both the household questionnaire and energy audit survey sought information on the presence and extent of dampness and condensation in each dwelling surveyed. Information was collected on a room by room basis, for the periods prior to the CHP improvements and subsequently, through questioning of the household and visual inspections of the individual rooms by the surveyors. Given the difficulties associated with identifying the actual cause of the problem, no distinction was made by the surveyors on whether the problem was condensation or some other form of dampness.
8.3 The presence of condensation and dampness was scored on a 3-point scale:
1. small spots on the walls or the ceiling or misting of window surfaces
2. hand-sized patches on the walls or the ceilings or streaming windows and minor pooling of water of window sills
3. large patches on walls or the ceilings, or the formation of large pools of water on the sills that risked overflowing onto the wall.
This information was then aggregated for the whole house and an overall average score for each dwelling was produced. The findings are presented below on an individual room basis before being summarised across the whole house.
8.4 From combining the information from the questionnaire and the energy audit survey, the majority of all of the individual rooms were recorded as being dampness and condensation-free for the periods before and after the CHP improvements (see Table 8.1). Subsequent to the CHP improvements, there is a reduction in the number of rooms where dampness or condensation was present, as well as a reduction in the overall severity of the condensation and dampness problem.
Table 8.1 Incidence and Severity of Dampness or Condensation
Room | Before CHP improvements | After CHP improvements |
|---|
Number of dampness and condensation-free dwellings | Average severity of dampness and condensation (across all dwellings) | Average severity of dampness and condensation (across only rooms with problem) | Number of dampness and condensation-free dwellings | Average severity of dampness and condensation | Average severity of dampness and condensation (across only rooms with problem) |
|---|
Lounge | 431
(n = 454) | 0.09 | 1.78 | 470
(n = 474) | 0.01 | 1.75 |
|---|
Main Bedroom | 412
(n = 454) | 0.18 | 1.90 | 468
(n = 474) | 0.03 | 1.62 |
|---|
Second Bedroom | 315
(n = 352) | 0.19 | 1.81 | 354
(n = 359) | 0.03 | 2.00 |
|---|
Third Bedroom | 115
(n = 175) | 0.27 | 1.74 | 173
(n = 177) | 0.03 | 1.50 |
|---|
Hall | 418
(n = 452) | 0.03 | 1.36 | 470
(n = 472) | 0.01 | 2.00 |
|---|
Kitchen | 399
(n = 453) | 0.19 | 1.95 | 462
(n = 473) | 0.04 | 1.64 |
|---|
Bathroom | 375
(n = 454) | 0.23 | 1.93 | 458
(n = 474) | 0.06 | 1.72 |
|---|
Overall House | 349
(n = 454) | 0.14 | 0.69 | 443
(n = 474) | 0.03 | 0.46 |
|---|
8.5 Generally, the use of more heating appears to have had a considerable effect on reducing the incidence and severity of condensation and dampness problems in the home. Where condensation and dampness problems had reportedly cleared completely, or the severity reduced, more heating was being used in:
- 34 of the 36 main bedrooms
- 24 of the 32 second bedrooms
- 17 of the 23 third bedrooms
- 8 of the 10 hallways
- 18 of the 39 kitchens
- 44 of the 45 bathrooms.
8.6 Overall, in 81.9% of all of the rooms where condensation or dampness problems had reportedly cleared completely, and lessened in another 4.2% of rooms subsequent to installing the new heating, more heating was used than before. In 12 of the rooms where there was no change in the use of the heating after the new system was installed, there was no change reported in the level of condensation.
8.7 When these room results were aggregated and averaged across the whole house, the overall incidence and severity of condensation and dampness decreased subsequent to the CHP improvements. The number of completely condensation and damp free homes increased from 349 (76.9%) prior to the CHP improvements to 443 (93.5%) afterwards (see Table 8.2). The average overall severity of condensation and dampness in the home fell from 0.69 on the 3-point scale before to 0.03 after the CHP improvements.
Table 8.2: Average severity of dampness or condensation: Overall dwelling
Severity of condensation (average on 3-point scale) | Number of Dwellings before CHP improvements | Number of Dwellings after CHP improvements |
|---|
No condensation | 349 | 444 |
|---|
up to 1 | 93 | 29 |
|---|
up to 2 | 10 | 1 |
|---|
up to 3 | 1 | 0 |
|---|
Presence of Mould in the Home
8.8 The presence of mould in the home was assessed in a similar way to the presence of condensation or dampness: through the questioning of the occupants and the visual inspection of the individual rooms by the surveyor. Again, the extent and severity of the mould was scored on a 3-point scale for both before and after the CHP improvements:
1. small spots on the walls or the ceiling;
2. hand-sized patches on the walls or the ceilings;
3. large patches on walls or the ceilings
8.9 The overwhelming majority of all the individual rooms were recorded as being mould-free for the periods before and after the CHP improvements (see Table 8.3). After the CHP improvements, there is a reduction in the number of rooms where mould is present, as well as a decline in the overall severity of the extent of mould.
Table 8.3: Incidence and Severity of Mould in Home
Room | Before CHP improvements | After CHP improvements |
|---|
Number of mould-free dwellings | Average severity of mould (across all dwellings) | Average severity of mould (across only rooms with problem) | Number of mould-free dwellings | Average severity of mould | Average severity of mould (across only rooms with problem) |
|---|
Lounge | 441
(n = 454) | 0.05 | 1.62 | 473
(n = 474) | 0.004 | 2.00 |
|---|
Main Bedroom | 428
(n = 454) | 0.11 | 1.92 | 470
(n = 474) | 0.01 | 1.25 |
|---|
Second Bedroom | 349
(n = 352) | 0.19 | 1.81 | 356
(n = 359) | 0.02 | 2.67 |
|---|
Third Bedroom | 161
(n = 175) | 0.16 | 2.07 | 174
(n = 177) | 0.03 | 1.67 |
|---|
Hall | 448
(n = 452) | 0.01 | 1.25 | 472
(n = 472) | * | * |
|---|
Kitchen | 416
(n = 453) | 0.17 | 2.11 | 463
(n = 473) | 0.04 | 1.90 |
|---|
Bathroom | 417
(n = 454) | 0.16 | 2.00 | 464
(n = 474) | 0.02 | 1.50 |
|---|
Overall House | 380
(n = 454) | 0.09 | 0.57 | 454
(n = 474) | 0.02 | 0.47 |
|---|
8.10 Again, the use of more heating appears to have had a considerable effect on reducing both the incidence and severity of mould problems in the home. In those rooms that were mould-free subsequent to the CHP improvements, more heating was used in:
- 3 of the 13 lounges
- 17 of the 26 main bedrooms
- 12 of the 20second bedrooms
- 10 of the 11 third bedrooms
- 2 of the 4 hallways
- 11 of the 21 kitchens
- 11 of the 28 bathrooms.
8.11 Overall, the mould problems reportedly cleared completely in 118 of the 154 (76.6%) rooms subsequent to the CHP improvements, of which more heating was used in 56% of these rooms. The severity of the mould problem was reduced in another 8 (5.2%) rooms where more heating was used. In 7 rooms where there was no change in the severity of the mould, there was no reported change in the use of the heating in that room
8.12 When these room results are aggregated and averaged across the whole house, the overall incidence and severity of mould has decreased subsequent to the CHP improvements. The number of completely mould-free homes increased from 380 dwellings prior to the CHP improvements to 454 afterwards (see Table 8.4). The average overall severity of mould in the home fell from 0.09 on the 3-point scale before, to 0.02 after the CHP improvements.
Table 8.4: Average severity of mould: overall dwelling
Severity of mould (average on 3-point scale) | Number of Dwellingsbefore CHP improvements | Number of Dwellingsafter CHP improvements |
|---|
No Mould | 380 | 454 |
|---|
up to 1 | 62 | 19 |
|---|
up to 2 | 11 | 1 |
|---|
up to 3 | 1 | 0 |
|---|
Overall Comment on Chapter Eight
8.13 Condensation and dampness problems were not as great a problem in the Year 2 survey as in Year 1. Increased use of heating, improved insulation, and extra ventilation are advocated as the solutions to tackling condensation and mould problems in homes. The CHP improvements addresses two of these solutions directly, and the dwellings with dampness, condensation and mould problems appear to have the reaped the benefits in terms of reducing both the number of dwellings suffering from condensation or dampness problems and mould problems, and the severity of these problems where they continue to persist.