Fall prevention through windows: barriers and balustrades (Nat)

Transcription

1 Fall prevention through windows: barriers and balustrades (Nat) BCA Volume Two Housing Provisions has been amended under BCA 2009 to require a balustrade or other barrier where it is possible for a person to fall through an openable window from a floor or the like that is more than 4 metres above the surface beneath. For BCA 2009, Balustrades or other barrier construction was amended by adding (a) (ii) (c) to specify a height for the balustrade or other barrier at an openable window of 865 mm for consistency with the similar provision in Volume One. Prior to this change, the height of the balustrade or other barrier at these locations was 1 m. The clause now reads: Clause Balustrades or other barrier construction (a) The height of a balustrade or other barrier must be in accordance with the following: (i) The height must not be less than 865 mm above the nosings of the stair treads or the floor of a ramp. (ii) The height must not be less than (A) 1m above the floor of any access path, balcony, landing or the like (see Figure ); or (B) 865mm above the floor of a landing to a stair or ramp where the balustrade or other barrier is provided along the inside edge of the landing and is not more than 500 mm long. (C) 865mm above the floor beneath an openable window The requirement to provide a balustrade or other barrier at an openable window has caused confusion because of the implication that where a window was part of the area below the mandated height it was to be treated as a barrier or balustrade. Additionally the question was asked whether clauses (c), (d) and (e), as reproduced below, also therefore applied to the window itself? (c) (d) (e) Openings in balustrades (including decorative balustrades) or other barriers must be constructed so that any opening does not permit a 125 mm sphere to pass through it and for stairs, the space is tested above the nosing line. A balustrade or other barrier must be designed to take loading forces in accordance with AS/NZS For floors more than 4 m above the surface beneath, any horizontal elements within the balustrade or other barrier between 150 mm and 760 mm above the floor must not facilitate climbing. The above is intended to provide general information in summary form. The contents do not constitute specific advice and should not be relied upon as such. Formal specific advice should be sought by members with respect to particular matters before taking

2 Page 2 Clarification was sought on these matters at the ABCB s Building Codes Committee (BCC) meeting held on 2 April 2009, where BCC provided advice on the following four questions. 1. On what basis do we determine if it is possible for a person to fall through an openable window? a. Where a window is capable of being opened to create a gap greater than that where a 125mm sphere could pass through; and b. The gap is less than 865mm above the floor. 2. If it is deemed not possible to fall through an openable window, or the window is not openable, is the window required to be designed to take the higher balustrade loadings in accordance with part (d), that is AS/NZS and the increased glass thickness required by the balustrade requirements of AS 1288? The window is not required to comply with the requirements of Clause 3.6 Barriers of AS/NZS The window is therefore required to have glass that complies with the normal selection criterion of AS That is, wind loading on the glass, glass area and human impact requirements for the location of the window in question. 3. Does the window itself constitute a barrier, or is a separate barrier required? The window is not a barrier as the glass selection requirements account for normal human impact provisions. No barrier is required to the window, provided the glass type and thickness is selected correctly, and, the requirements for openable windows set out in 1 above are met The philosophy behind the answers above is that if one is able to verify that if a person is not capable of falling out of a window, then the balustrade requirements do not apply. Likewise for fixed glass windows, the glass selection needs to be the sole consideration. Hence awning windows with standard winders are acceptable provided they cannot be opened more than 125mm, and horizontal sliders and double hung windows would need a means of permanently restricting the maximum opening size to 125mm. 4. Are window sills deemed to be able to facilitate climbing? Yes, if the sill is between 150mm and 760mm above the floor.

3 Page 3 The following drawings are industry standard configurations commonly used on two storey domestic housing. They illustrate various situations that meet these requirements and would restrict a person from falling through the window. Note Awning windows fitted with a standard 300mm chain operator will leave an opening of about 260 mm. Awning windows fitted with a restricted 125mm chain operator will leave an opening of about 80mm. The following scenarios are represented in Diagrams 1, 2 & 3. Case 1(a): Case 1(b): Case 2(a): A window with a transom above 865mm, sill height less than 150mm and unrestricted opening above the transom. A window with a transom above 865mm, sill height greater than 150mm and opening restricted to 125mm above the transom. A window with a transom below 865mm, sill height less than 150mm and opening restricted to 125mm above the transom. The following scenarios have no diagrams. Case 2(b): Case 3: Case 4: An awning window with a transom below 865mm, Sill height less than 150mm, fitted with a standard 300mm chain operator leaving an opening of about 260mm. This configuration does not meet the 125mm gap requirement and would not be deemed compliant. A window with no transom, sill height greater than 150mm, opening restricted to 125mm above the transom. A window with no transom, sill height below 865mm. For further information on the BCA or these requirements, HIA members can contact HIA s Building Services staff on or hia_technical@hia.com.au. If you would like to become a HIA member, contact or enquiry@hia.com.au

4 Page 4 Diagram 1 - Case 1(a)

5 Page 5 Diagram 2 - Case 1(b)

6 Page 6 Diagram 3 - Case 2 (a)