BS 5250:1989

Foreword
Committees responsible
Section one. General
1. Scope
2. Definitions
Section two. The nature of condensation
3. Behaviour of water vapour in air
4. Causes of condensation
5. The effects of condensation and high humidity
Section three. Design to control condensation
6. Design objectives
7. Design procedure
8. Design principles
9. Application of design principles
Section four. Existing buildings
10. Diagnosis and remedial work
11. Particular aspects
Section five. Precautionary measures during building
works
12. Construction information
13. Site checks
Section six. Building user information
14. Manual format
15. Particular aspects
Appendices
A. The interrelationship of moisture contents and
    temperatures
B. Tables of thermal and vapour properties
C. Assessment of surface condensation risk
D. Assessment of interstitial condensation risk
E. Vapour resistances: conversion factors for unusual
    units
F. Bibliography
Tables
1. Typical moisture generation rates for household
    activities
2. Typical moisture generation rates from heating fuels
3. Daily moisture generation rates for households
4. Typical ventilation rates
5. Saturation vapour pressures for aid temperatures
    30.9 deg C - 20 deg C
6. Thermal and vapour resistivities
7. Vapour resistances
8. Thermal resistances for surfaces and air spaces
9. Total fabric thermal transmittance
10. Environmental conditions for HIGH moisture input
11. Environmental conditions for LOW moisture input
12. Conversion factors for unusual units
Figures
1. Relationship between air temperature, vapour pressure
    (moisture content) and relative humidity
2. Flow chart for condensation control
3. Balance of factors
4. Masonry cavity wall
5. Framed wall
6. Framed wall with tile cladding
7. Solid wall: internal insulation
8. Solid wall: external insulation
9. Pitched roof
10. Cross section through pitched roof
11. Lean-to roof
12. Pitched roof: insulation on pitch
13. Cross section through roof: ventilation at high
    and low levels
14. Pitched roof: minimum airspace between sarking and
    insulation
15. Pitched roof: inclined vapour resistant insulation
16. Ventilation positions for room in the roof
    constructions requiring ventilation
17. Ventilation positions for room in the roof
    construction requiring ventilation
18. Ventilation positions for roofs with dormers
19. Timber flat roof: cold type
20. Timber flat roof: minimum airspace between roof deck
    and insulation
21. Timber flat roof: warm type
22. Timber flat roof: warm type inverted
23. Concrete flat roof: cold type
24. Concrete flat roof: minimum airspace between roof
    deck and insulation
25. Concrete flat roof: warm type
26. Concrete flat roof: warm type inverted
27. Timber suspended ground floor
28. Precast concrete suspended ground floor
29. Solid ground floors
30. Timber deck with external finish of low vapour
    resistance
31. Suspended concrete slab
32. Uninsulated steel lintel
33. Steel lintel with insulation
34. Concrete boot lintel with insulation
35. Typical heat flow paths at a solid lintel
36. Jamb to cavity wall with an insulated return
37. Concrete sill with an insulated back
38. Wall/roof junction with overlapping insulants
39. Parapet/roof junction with insulation
40. Floor/wall junction with external insulation
41. Multi-directional thermal bridge paths at wall/
    ground floor junction
42. Wall/ground floor junction with insulation
43. Standard unit
44. Stepped unit
45. Example of use of the psychrometric chart
46. Psychrometric chart
47. Typical semi-detached dwelling
48. Relationship between r.h. and ventilation rate for
    HIGH moisture input
49. Relationship between r.h and ventilation rate for
    LOW moisture input
50. Pro forma worksheet example
51. Example 1. Brick/insulation/block wall: calculation
    worksheet
52. Example 1. Brick/insulation/block wall: graphical
    determination of condensation planes
53. Example 2. Unventilated cold deck flat roof:
    calculation worksheet
54. Example 2. Unventilated cold deck flat roof:
    graphical determination of condensation planes
55. Condensation predicted at one interface
56. Condensation predicted at two interfaces
57. Condensation predicted at three interfaces
Index

Causes and effects of condensation in buildings both new and existing and recommendations for their control. Methods to determine the occurrence and assess the effects of surface condensation on mould growth and interstitial condensation. Guidance on assessing whether any such condensation may be considered harmful.