Appendix F: Assessing air permeability of older dwellings in relation to permanent ventilation requirements

F1 The minimum requirements for permanent ventilation for certain appliances depend on a knowledge of the air-tightness of the dwelling where they are to be installed, Dwellings built after 2008 are likely to have evidence of the air-tightness either through an individual air permeability test certificate or through representative testing of the same design of dwelling on the same housing development. F2 Older houses are unlikely to have been tested but are unlikely to achieve an air permeability of less than 5.0 m³/(h.m²) at 50 Pa unless the building fabric has been substantially upgraded. That would include all or most of the following measures:

  • Full double (or triple) glazing
  • Effective closures on trickle vents and other controllable ventilation devices
  • All external doors with integral draught seals and letter box seals
  • Internal and external sealing around external doors and window frames
  • Filled cavity or solid walls
  • Impermeable overlay and edge sealing of suspended ground floors
  • Careful sealing at junctions between building elements such as between walls and floors or ceilings
  • Careful sealing around loft hatch
  • Careful sealing around chimney or flue penetrations
  • Careful sealing around internal soil pipe
  • Careful sealing around domestic water and heating pipes passing into externally ventilated spaces
  • Careful sealing of all service penetrations in the building fabric (electricity, gas, water, drainage, phone, TV aerial, )
  • Internal warning pipe for WC
  • All cable channels for light switches and power sockets sealed
  • All cable entry for lighting and ceiling roses Recessed lighting should not penetrate ceilings separating loft spaces.
F3 Failure to implement even a few of these measures will typically mean that the overall air permeability will probably exceed 5.0 m³/(h.m²) at 50 Pa. However, individual rooms in some older houses with solid walls and solid floors can be inherently air-tight when fitted with modern glazing. The situation may therefore need to be assessed with respect both to the overall dwelling and to the individual room where the appliance is to be fitted. If in doubt then assume that the air permeability is lower than 5.0 m³/ (h.m²) at 50 Pa and fit the appropriate permanent ventilation or seek specialist advice. Further information on sources of air leakage can be found in GPG224 Improving airtightness in dwellings.

  • Diagram 1 Boundaries in this Approved Document Part  J Diagram 1 Boundaries in this Approved Document Part J
  • Diagram 2 Chimneys and flues Part J Diagram 2 Chimneys and flues Part J
  • Diagram 3 Draught diverter and draught stabiliser Part J Diagram 3 Draught diverter and draught stabiliser Part J
  • Diagram 4 Types on installation Part J Diagram 4 Types on installation Part J
  • Diagram 5 Fireplace recesses Part J Diagram 5 Fireplace recesses Part J

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    Diagram 6 the function of hearths Part J Diagram 6 the function of hearths Part J
  • Diagram 7 Measurement of flues and ducts Part J Diagram 7 Measurement of flues and ducts Part J
  • Diagram 8 General air supply to a combustion appliance (for sizes see Section 2,3 and 4) Part J Diagram 8 General air supply to a combustion appliance (for sizes see Section 2,3 and 4) Part J
  • Diagram 9 Ventilator free areas Part J Diagram 9 Ventilator free areas Part J
  • Diagram 10 Location of permanent air vent openings,some examples Part J Diagram 10 Location of permanent air vent openings,some examples Part J
  • Diagram 11 Provision of permanent air vent openings in a solid floor Part J Diagram 11 Provision of permanent air vent openings in a solid floor Part J
  • Diagram 12 Material change of use fire protection of chimneys passing through other dwellings Part J Diagram 12 Material change of use fire protection of chimneys passing through other dwellings Part J
  • Diagram 13 The separation of combustible material from factory made metal chimney designated to BS EN 1856 part 1 2003 Part J Diagram 13 The separation of combustible material from factory made metal chimney designated to BS EN 1856 part 1 2003 Part J
  • Diagram 14 Example locations of access panels for concealed horizontal flues Part J Diagram 14 Example locations of access panels for concealed horizontal flues Part J
  • Diagram 15 Bends in flues Part J Diagram 15 Bends in flues Part J
  • Diagrams 16 Example notice plate for hearths and flues Part J Diagrams 16 Example notice plate for hearths and flues Part J
  • Diagram 17 Flue outlet positions for solid fuel appliances Part J Diagram 17 Flue outlet positions for solid fuel appliances Part J
  • Diagram 18 Flue outlet positions for solid fuel appliances clearances to easily ignited roof coverings Part J Diagram 18 Flue outlet positions for solid fuel appliances clearances to easily ignited roof coverings Part J
  • Diagram 19 Protecting combustible material from uniinsulated fluepipes for solid fuel appliances Part J Diagram 19 Protecting combustible material from uniinsulated fluepipes for solid fuel appliances Part J
  • Diagram 20 Wall thicknesses for masonry and flueblock chimneys Part J Diagram 20 Wall thicknesses for masonry and flueblock chimneys Part J
  • Diagram 21 Minimum separation distances from combustible material in or near a chimney Part J Diagram 21 Minimum separation distances from combustible material in or near a chimney Part J
  • Diagram 22 Construction of fireplace gathers Part J Diagram 22 Construction of fireplace gathers Part J
  • Diagram 23 Canopy or an open solid fuel fire Part J Diagram 23 Canopy or an open solid fuel fire Part J
  • Diagram 24 Constructional hearth suitable for a solid fuel appliance (including open fires) Part J Diagram 24 Constructional hearth suitable for a solid fuel appliance (including open fires) Part J
  • Diagram 25 Constructional hearth suitable for a solid fuel appliance (including open fires) Part J Diagram 25 Constructional hearth suitable for a solid fuel appliance (including open fires) Part J
  • Diagram 26 Non combustible hearth surface surrounding a solid fuel appliance Part J Diagram 26 Non combustible hearth surface surrounding a solid fuel appliance Part J
  • Diagram 27 Ways of providing hearths Part J Diagram 27 Ways of providing hearths Part J
  • Diagram 28 Fireplace recesses Part J Diagram 28 Fireplace recesses Part J
  • Diagram 30 Wall adjacent to hearths Part J Diagram 30 Wall adjacent to hearths Part J
  • Diagram 31 Types of gas fires Part J Diagram 31 Types of gas fires Part J
  • Diagram 32 Free areas of permanentlt open air vents for gas appliance installations (other than decorative fuel effect fires or flueless appliances) Part J Diagram 32 Free areas of permanentlt open air vents for gas appliance installations (other than decorative fuel effect fires or flueless appliances) Part J
  • Diagram 33 Ventilation for flueless gas appliances Part J Diagram 33 Ventilation for flueless gas appliances Part J
  • Diagram 34 Location of outlets from flues serving gas appliances Part J Diagram 34 Location of outlets from flues serving gas appliances Part J
  • Diagram 35 Location of outlets near roof windows from flues serving gas appliances Part J Diagram 35 Location of outlets near roof windows from flues serving gas appliances Part J
  • Diagram 36 Bases for back boilers(installation using a proprietary back boiler enclosure shown) Part J Diagram 36 Bases for back boilers(installation using a proprietary back boiler enclosure shown) Part J
  • Diagram 37 Hearths for decorative fuel effect(DFE) and inset live fuel effect (ILFE) fires minimum plan dimensions of non combustible surfaces Part J Diagram 37 Hearths for decorative fuel effect(DFE) and inset live fuel effect (ILFE) fires minimum plan dimensions of non combustible surfaces Part J
  • Diagram 38 hearths for other appliances plan dimensions of non combustible surfaces Part J Diagram 38 hearths for other appliances plan dimensions of non combustible surfaces Part J
  • Diagram 39 Shielding of appliances Part J Diagram 39 Shielding of appliances Part J
  • Diagram 40 Free areas of permanently open air vents for oil-fired appliance installations Part J Diagram 40 Free areas of permanently open air vents for oil-fired appliance installations Part J
  • Diagram 41 Location of outlets from flues serving oil fire appliances Part J Diagram 41 Location of outlets from flues serving oil fire appliances Part J
  • Diagram 42 Location of an oil fired appliance in relation to its hearth.Minimum dimensions of the heat resistant material in the hearth and the clear zone of non combustible surface Part J Diagram 42 Location of an oil fired appliance in relation to its hearth.Minimum dimensions of the heat resistant material in the hearth and the clear zone of non combustible surface Part J

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    Diagram 43 Separation of liquefied petroleum gas tanks of up to 1.1 tonne capacity from buildings,boundaries and fixed sources of ignition Part J Diagram 43 Separation of liquefied petroleum gas tanks of up to 1.1 tonne capacity from buildings,boundaries and fixed sources of ignition Part J

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    Diagram 44 Location of LPG cylinders Diagram 44 Location of LPG cylinders Part J
  • Table 1 Air supply to solid fuel appliances Part J Table 1 Air supply to solid fuel appliances Part J
  • Table 2 Size of flues in chimneys Part J Table 2 Size of flues in chimneys Part J
  • Table 3 Minimum performance designations for chimney and fluepipe components for use with new solid fuel fired appliances Part J Table 3 Minimum performance designations for chimney and fluepipe components for use with new solid fuel fired appliances Part J
  • Table 5 Size of flues for gas-fired appliances Part J Table 5 Size of flues for gas-fired appliances Part J
  • Table 6 Minimum performance designations for chimney and fluepipe components for use with new gas appliances Part J Table 6 Minimum performance designations for chimney and fluepipe components for use with new gas appliances Part J
  • Table 7 Protecting buildings from hot flues Part J Table 7 Protecting buildings from hot flues Part J
  • Table 8 Minimum performance designations for chimney and fluepipe components for use with new oil fired appliances with flue gas temperatures less than 250deg celsius Part J Table 8 Minimum performance designations for chimney and fluepipe components for use with new oil fired appliances with flue gas temperatures less than 250deg celsius Part J
  • Table 9 Protecting buildings from hot flues for flue gas temperature not more than 250deg celsius Part J Table 9 Protecting buildings from hot flues for flue gas temperature not more than 250deg celsius Part J
  • Table 10 Fire protection for oil storage tanks Part J Table 10 Fire protection for oil storage tanks Part J
  • Table 11 Fire protection for LPG storage tanks(see Diagram 43) Part J Table 11 Fire protection for LPG storage tanks(see Diagram 43) Part J
  • Table to Diagram 41 Location of outlets from flues serving oil fired appliances Part J Table to Diagram 41 Location of outlets from flues serving oil fired appliances Part J
  • ]Examples See Paragraph 1.55 Part J Examples See Paragraph 1.55 Part J

  • Calculation of opening area of Fireplace Part J Calculation of opening area of Fireplace Part J
  • See Diagram 40 Calculation of Vents for Open flue appliance Part J See Diagram 40 Calculation of Vents for Open flue appliance Part J
  • Calculation of Vents for Open flue boiler Part J Calculation of Vents for Open flue boiler Part J
  • Form Hearth,fireplace flues and chimneys Part J Form Hearth,fireplace flues and chimneys Part J

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    Table to Diagram 34 Location of outlets from flues serving gas appliances Part J Table to Diagram 34 Location of outlets from flues serving gas appliances Part J
  • Table G1 Temperature Classes Table G1 Temperature Classes Part J
  • Table G2 Pressure Classes Part J Table G2 Pressure Classes Part J
  • [caption id="attachment_8311" align="alignnone" width="1129"]Table G3 Corrosion resistance classes Part J Table G3 Corrosion resistance classes Part J