Reply To: Regulations for windows
The Building Regulations (Section B1, Second Schedule) require that â€œa building shall be so designed and constructed that there are adequate means of escape in case of fire from the building to a place of safety outside the building, capable of being safely and effectively usedâ€.
The Technical Guidance Documents are merely guidance in how to comply with the requirements of the Regulations. The Introduction to Part B (Fire Safety) clearly states this and goes on to say â€œthe adoption of an approach other than that outlined in the guidance is not precluded provided that the relevant requirements of the Regulations are complied withâ€
The TGD â€˜Bâ€™ also states (1.5.6.b) that â€œThe bottom of the window opening should be not more then 1100mm and not less then 800 above the floor level in the room in which it is situatedâ€.
In this instance I would assume that the disabled person would be accommodated on the ground floor as it would be unreasonable to assume that she would be able to exit unaided from a first floor window. On the ground floor there is usually no requirement for guarding (which becomes a requirement when the height differential is greater then 600mm). Therefore, ground floor windows can reasonably have the sill below 800mm above floor level. Any glazing below 800mm from floor level would though need to be toughened or laminated.
On first floor windows there is an obvious requirement for guarding and TGD â€˜Kâ€™ (2.4) states â€œWhere the window is capable of being opened, special care must be taken to ensure that the guarding must remain in place and effective at all timesâ€. If this provision can be safely met there would appear to be no reason why the bottom of the window cannot extend below 800mm above floor level. In fact the equivalent guidance for England & Wales, Approved Document â€˜Bâ€™ (2.11.b) states â€œThe window should have an unobstructed openable area that is at least 0.33m Â² and at least 450mm high and 450mm wideâ€¦.The bottom of the openable area should not be more than 1100mm above the floor.â€
This guidance, 2000 edition, is more up to date then the 1997 Irish guidance.
In other words, as some of the more astute readers may have deduced, you donâ€™t have to follow the TGD literally. A practical application of this from a fenestration perspective is that it will allow the use of windows other then your bog-standard 500x850mm casement window as an escape window â€“ a sliding sash window for example.