search.noResults

search.searching

dataCollection.invalidEmail
note.createNoteMessage

search.noResults

search.searching

orderForm.title

orderForm.productCode
orderForm.description
orderForm.quantity
orderForm.itemPrice
orderForm.price
orderForm.totalPrice
orderForm.deliveryDetails.billingAddress
orderForm.deliveryDetails.deliveryAddress
orderForm.noItems
EXTERNAL ENVELOPE High rise not high risk!


Danny Birrel of Kawneer advises on how to design curtain wall facades to accommodate building movement


L


and-pressed developers are increasingly turning to high-rise buildings to deliver best footprint


value but the interaction between the facade of a building, particularly a tall one, and its structure is, sadly, frequently ignored in the design phase.


Analysis of the architectural intent, structural movements and specified glazing system is required during the early stages of a project design so that glazing and cladding systems can be designed to allow for build- ing movement without compromising the performance or safety of the system. Failure to provide sufficient allowance for in-service building movement in the connections between facade and structure may result in one or more issues, such as leaks, cracks, failure of connections, buckling of mullions or breakage of glass. Due to the extension of structural spans seen in contemporary building designs, slab deflection is increasingly placing additional demands on the facade design team to accommodate this differential movement between slab and facade. The solution to this is simple – early engagement with system specialists. While analysis of the structural movements, architectural intent and specified glazing system is usually carried out by the system supplier or specialist facade contractor, it is imperative that main contractors and building designers also engage with the system specialists during the early planning stages to ensure the proposed facade system can accommodate the associated building movements and is in line with the proposed site installation methodology. If the specified glazing system is not aligned with the building structure and installation plan at the early stages of a project, it can cause unforeseen delays and costs when it is aligned at a later stage. Accommodating building movement and the resulting interaction between the facade and structure is complex and there are many factors to consider. These include tempera- ture, moisture, floor loading, wind loading, snow loading, live loads, dead loads, settle- ment, creep and seismic sway.


ADF APRIL 2019


Selecting the most appropriate glazing system at the early stages in a project is vital as it can have a major impact on the intended appearance, and more importantly, lifetime performance. For example, wider framing members can accommodate more building movement, and in some instances double transom details are required at floor slabs for the accommoda- tion of differential building movement. One of the main complexities is designing the facade to accommodate differential slab deflection. These movements caused by post-installation dead and live loads are commonly found in the structural engineer’s report, which are typically defined by a span ratio. Due to a desire to extend structural spans in modern structures, slab deflection figures based on the span ratio are increasing significantly, making facade design and movement accommodation even more challenging. Arguably, floor slabs do not deflect


anywhere near the figures being documented but it is essential to design facades as if they do, including an allowance for manufactur- ing tolerances and thermal movement. Determining the limitations of a particular system or offered solution must be understood before complete alignment can take place. Failure to provide sufficient allowance within the system, or to design and/or specify a system with serious limitations, and failure to correctly design/detail the critical connections between the facade and structure may result in the issues mentioned earlier. Evaluating the various curtain walling options should be a first-case scenario as although conventional stick curtain walling is widely specified in the UK and can offer a cost-effective solution, compared to a unitised curtain wall it is very limited in terms of accommodating differential slab deflections.


Kawneer has recently developed a movement/expansion joint for ‘stick’ curtain wall systems that can accommodate up to +/- 15 mm of differential slab movement, so mimicking the ability of unitised solutions


WWW.ARCHITECTSDATAFILE.CO.UK


57


Determining the limitations of a particular system or offered solution must be understood before complete alignment can take place


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92