View source for Three Snowhill, Birmingham

==Article in [https://www.newsteelconstruction.com/wp/wp-content/uploads/digi/NSC_Sept18digi/pubData/source/NSC_Sept18digi.pdf#page=22 NSC September 2018]==
{{#image_template:image=File:Three_Snowhill-1.jpg|align=right|wrap=true|caption=The Scheme was originally envisaged as twin residential and hotel towers|width=300}}
'''Three up in second city'''<br>
The third of three [[Braced_frames|steel-framed]] [[Multi-storey_office_buildings|office blocks]] in Snowhill, Birmingham, is one of the UK’s largest speculative office developments to be constructed outside of London.<br>
''By Martin Cooper''<br>

Sat next to its sister buildings (One and Two Snowhill – see [https://www.newsteelconstruction.com/wp/wp-content/uploads/digi/2008pdf/0801NSCJan08.pdf#page=16 NSC January 2008] and [https://www.newsteelconstruction.com/wp/wp-content/uploads/digi/2012pdf/1209NSCSepOct12.pdf#page=22 September 2012]), Three Snowhill is a 19-storey [[Multi-storey_office_buildings|office tower]] that forms a stunning gateway to the city’s business district, completing the final phase of Ballymore’s Snowhill Estate development. Offering nearly 38,000m<sup>2</sup> of [[Sustainability#Understanding BREEAM|BREEAM ‘Excellent’]] rated Grade A office floor space, together with retail and leisure units at podium and ground floor levels, the building sits atop four levels of concrete basement and podium substructure. Three Snowhill, like its sister buildings, has a [[Composite_construction|composite design]] comprising a steel frame, with [[Steel_construction_products#Cellular beams|cellular beams]] supporting [[Steel_construction_products#Decking for floors|metal decking]]. As well as accommodating the office block’s services within the structural void, the Fabsec [[Steel_construction_products#Cellular beams|cellular beams]] have proven to be a cost-efficient option to create 10.5m-long internal spans.

This final plot of the Snowhill development has a long and varied history as initially twin residential and [[Residential_and_mixed-use_buildings#Hotels|hotel towers]], both constructed with reinforced concrete frames, were envisaged. In 2007 work began on this scheme and all of the basement and substructure work had been completed when the job was halted a year later. Due to market conditions, a redesign was undertaken and the project was resurrected as a solitary [[Multi-storey_office_buildings|commercial block]], which in turn led the team to choose a steel framing solution.

WSP Associate Director James Bodicoat says: “A single tower on the site necessitated some substantial alterations to the substructure, most notably a much thicker raft to accommodate the different loads. This meant the five-storey basement became four storeys as the lowest level was in-filled.”

Instead of two main [[Concept_design#Concrete or steel cores|cores]], one for each tower, the new scheme now has three [[Concept_design#Concrete or steel cores|concrete cores]], which provide the [[Concept_design#Structural options for stability|stability]] for the single tower. Two of the [[Concept_design#Concrete or steel cores|cores]], situated along the north elevation have the functionality of one core but are structurally independent. They are however linked together by steelwork that forms a frame for scenic lifts and a large [[Steel-supported_glazed_facades_and_roofs|glazed façade]].
{{#image_template:image=File:Three_Snowhill-2.jpg|align=left|wrap=true|caption=The structure has a large central [[Steel-supported_glazed_facades_and_roofs#Atrium Roofs and Sky lights|atrium]] that will have a glazed roof|width=300}}
Working on behalf of main contractor BAM Construction, Severfield has [[Fabrication|fabricated]], supplied and [[Construction#Steel erection|erected]] some 4,500t of steel for this project. All of the steelwork has been [[Construction#Steel erection|erected]] via the site’s three [[Construction#Tower cranes|tower cranes]], as none of the elements exceed 13t in weight.

Although the project sits on a busy inner-city area, it is well served with two material laydown areas, running along two main elevations, which have allowed steelwork to be delivered on a regular daily basis. While the city centre location has provided challenges with logistics, Severfield worked very closely with the site team to co-ordinate deliveries. Using its offload system has proved particularly useful, allowing the unloading of two [[Fabrication#Handling and transportation|steel deliveries]] at one time despite the tight conditions on site.

The building wraps around a large central [[Steel-supported_glazed_facades_and_roofs#Atrium Roofs and Sky lights|atrium]], which allows plenty of natural light to penetrate the building’s inner areas as it is topped with a glazed roof. This [[Steel-supported_glazed_facades_and_roofs|glazing]] also spans over the double-height upper floor, creating a large light-filled breakout space. A series of steel CHS trees, each with either two or three branches, along with CHS rafters support the [[Steel-supported_glazed_facades_and_roofs#Atrium Roofs and Sky lights|glazed roof]] on this upper level.

Large parts of the building’s roof support plant areas and, in order to create a visual screen to hide the equipment, two elevations have a 5m over sail. This high-level element is formed by a series of cantilevering [[Trusses|trusses]].

Possibly the most standout feature of the scheme are the raking [[Facades_and_interfaces|façades]] which, as well as providing the building with some architectural highlights, help the project to maximise the available floor space as the building’s floorplates gradually increase as one ascends towards the uppermost floor. The building’s north west and north east corners both feature raking [[Facades_and_interfaces|façades]], formed by a series of [[Steel_construction_products#Structural hollow sections|CHS]] columns, founded at basement level on large 5m-high steel nodes. The nodes have [[Construction#Site bolting|bolted connections]] to the raking columns, which merge at the ground floor level, and to perimeter perpendicular columns. Weighing approximately 9t each, the nodes are either connected to two or three columns, depending on their location.
<gallery mode="packed" widths=300px heights=250px> 
Image:Three_Snowhill-3.jpg| 
Image:Three_Snowhill-4.jpg|A [[Composite_construction|steel composite]] design was chosen for the new scheme 
Image:Three_Snowhill-5.jpg|The raking façade’s columns are founded at basement level on large nodes
</gallery>
<br>
Another sloping [[Facades_and_interfaces|façade]] is located on the south east corner, where a portion of the building, extending from level three to eight, is suspended from three large raking columns. “Severfield’s [[Design|design]] department has been key in developing solutions to issues such as the hung steelwork on the south east elevation, which had to be temporarily propped before it was fully suspended,” says BAM Senior Site Manager Charlotte Owen.

Summing up the benefits of the [[Braced_frames|steel-framed]] [[Design|design]], Ms Owen adds: “The steelwork frame installation sequence has allowed us to maximise programme benefits for following trades. For example, the floorplates being split in to four areas allows us to concrete the floors in two halves and then start installing the [[Facades_and_interfaces#Curtain walling|curtain walling]], while still ensuring exclusion zones are maintained for the steelwork erectors. By using steelwork, we have been able to monitor progress closely and forecast key milestone completion dates as the piece count is easy to measure on a weekly basis.”

Three Snowhill is due to complete by Spring 2019.

{|class="wikitable" width="400"
|-
|'''Architect'''||Weedon Architects
|-
|'''Structural Engineer'''||WSP
|-
|'''Steelwork Contractor'''||Severfield
|-
|'''Main Contractor'''||BAM Construction
|-
|'''Main Client'''||Ballymore Properties
|}

[[Category:Case studies - Multi-storey office buildings]]