Transforming an old brewery into six urban offices!
We were tasked with installing two mezzanine floors and new steel rafters for a development in Bournemouth for a returning client of ours.
The initial plans provided to us were very basic so we set to work with digitally surveying the two buildings with our Leica total station, most importantly to see how plum the walls were ‘not very’
Once we had downloaded the data, we soon realised the difference in the building shape compared to the original clients survey. Working with Smith Foster structural engineers we worked together to produce a scheme for new mezzanine floors and for the removal of the existing roof truss chords to provide first floor office space, this element of the project was always going to be a challenge with a fair amount of temporary works necessary prior to any removal.
Moving forward we decided to create a BIM model to fully understand the proposed steel layout, connections etc this is a critical element and assists the fabricators, which in return saves time and keeping on budget
Feel free to have an orbit of the draft model.
Once all the working drawings were ready and ‘double, triple’ checked, we worked closely with our chosen fabricators to start producing the steel sections for the mezzanine floors, this was approximately a 3 week turn around, which during this time the required pits for the first supporting columns were excavated along with the installation of the specialist padstones for the supporting beams.
Once the steel arrived on site, perfectly marked ready for positioning we setup the genie lifts ready for the first sections to be lifting and bolted to the columns, we left the columns free to ensure perfect positioning prior to concreting the holding down bolts, this was achieved be our surveying equipment, it was critical we were plum to the ridge of the roof although that element was a way off.
The first unit took us approx 7 days to install, this included moving all the sections into place and constantly checking their positions. (the delivery location was not on the doorstep!)
We swiftly started on the mezzanine in the next unit whilst the carpenters joisted out the first unit ready for decking so we could start our final checks for the order of the steel rafters. (more importantly our working platform!)
So a few weeks later we return to the finished decked out mezzanine floor ready for the temporary propping of the existing roof structure. And the challenge of hoisting the steels into position! as above this was never going to be an easy task, only a challenge.
There was no easy way of doing this, the stair void was left open for us to carefully maneuver the six 6m cranked lengths and 3 columns onto the mezzanine floor ready to slowly hoist into place. Each crank had a different angle due to the out of shape roof, mainy stressed purlins, some as precise as 29.8 degree etc.
Once propped we carefully removed the old truss chords, starting from the middle, this was a tedious and slow process but nevertheless went as smoothly as possible. The posts were positioned, with very little tolerance ready for the first cranked rafters.
The first rafters slowly hoisted into place, using genie lifts and a specialist made jig.
Using hollow sections the posts are tied together at the ridge height, each rafter was fixed at each rafter using a precision magnetic drill specifically for tight spaces, pre-drilling was never a good idea with old structures.