Table 1. Results from yes/no questions to contractors and surveyors.
| Question | Contractor responses (n = 51) | Surveyor responses (n = 71) | ||
|---|---|---|---|---|
| Yes | No | Yes | No | |
| Q1: Was there evidence of defects or structural damage to the residential building caused by the Japanese knotweed? | 2% (1) | 98% (50) | 6% (4) | 94% (67) |
| Q2: Was there evidence of defects or structural damage to retaining garden walls, sheds, garages, greenhouses or lightly built garden structures caused by the Japanese knotweed? | 35% (18) | 65% (33) | 23% (16) | 77% (55) |
| Q3: Was there evidence of defects or structural damage to drains, sewers and other subterranean services caused by the Japanese knotweed? | 16% (8) | 64% (43) | 3% (2) | 97% (66) |
| Q4: Was there evidence of loss of amenity to the garden or grounds resulting from the presence of Japanese knotweed? | 51% (26) | 49% (21) | 18% (13) | 82% (55) |
Notes:
Results are presented as percentages for easier comparison between contractor and surveyor respondents and rounded to the nearest whole number. The actual number of responses are included in brackets. n = sample size. Three surveyors did not answer the third and fourth questions making n = 68 for those responses (see Supplemental Information S1 for more details).