Claridge's 'Mega Basement Build'

06-03-2023

The Project

In the heart of London’s Mayfair, the Grade II listed, five-star hotel, Claridge’s, has been on its current site since the 1850s. The owners had been planning expansion work for some time to improve its offering to their clientele.

The ambitious expansive work planned included creating a new five-story basement. In place would be a spa, 2 swimming pools, gym, wine cellar, kitchen, back of house facilities and new plant room.

To be one of the biggest basements in the country, it would go as deep as the hotel is high. The five story, 65,000sqft space would take over 6 years to complete and open to hotel guests. This ambitious project began in 2015.

The Challenge

This seemingly impossible renovation had many challenges. The managers of Claridge’s were insistent that closing the hotel whilst the renovation commenced was not an option. Claridge’s clientele would find other hotels to stay and would simply not return.

Throughout the project, Claridge’s upmost priority were the guests and they had to ensure their guests were not disturbed during their stay. Any complaints were made, and work would have to stop.

All contractors at every stage of the project had strict time schedules of when work could commence and the noise limits.

The work was carried out in tightest of spaces. Products and systems selected had to be adaptable to the requirements of the project. Meticulous planning and coordination were required throughout.

Phase One – Structural Work

The new basement first had to be excavated. Miners from Ireland, renowned for their expertise, were brought in to embark on the almost impossible mission. In the only excavation of its kind to ever have happened in the UK, the first phase involved digging a network of tunnels just two meters under the art deco guest lounge.

The plan was to dig vertically down creating 61 shafts, 30 meters deep into the dense earth. Concrete would then be poured to form foundations of 23-meter-deep columns which the art deco wing would balance on and would allow the minors to excavate the earth around the shafts.

To avoid disturbing the guests staying in the hotel, the miners were to dig out the vast subterranean extension under Claridge’s hotel by hand. In total, the miners would remove 45,000 tones of London clay. This first phase of the renovation would take just over 2 years to complete.

Phase two – Basement Layers

Now that the hotel is settled onto the new 61 foundation columns, work can begin to create the 5-level basements.

Contractors started a top-down excavation; they would excavate down to the first level, then pour in reinforced concrete to create the floor of each basement and ceiling to the level below.

Once completed, they can move down to the next level until all 5 floors are created. In total 5,000 cubic meters of the earth is removed for each level.

This part of the phase was much quicker due to being able to dig with machinery and took just over 1 year to complete.

Plant Room

As part of the hotel's upgrade, the engine room for the plumbing and wiring was moved from the rooftop to 55 meters down to the deepest level of the basement. This would allow for the re-development of the upper floors with 40 new rooms & new six-star suites.

The new ‘nerve center’ would then be joined to the network of pipes back on the other side of the hotel. To do this, at the same time as they started the basement excavation, the team dug two 4-meter-wide vertical channels beneath the hotel. Once at the 5th level, two horizontal tunnels were then dug to join to the bottom of the vertical shafts. Over 100 meters of pipework could then be connected across the hotel.

In 2020, using offsite modular construction, 70 tonnes of new plant room machinery were installed into the 5th-level level basement, ahead of schedule.

Supply of Products

To overcome all the challenges, plant room contractors needed reliable suppliers. Especially a supplier who could organize just-in-time delivery of high-quality, specialist products.

Brymec was appointed as one of the chosen suppliers for this expansive project. With more than 40 years of experience, Brymec was ready to help support contractors with the products required for the plant room.

Product Selection

Only the best, highest quality products could be used on the project, which also has the performance to be able to cope with the hotel requirements.

Over 900 Brymec Cast Iron Valves were installed as an integral part of the plumbing & heating system whilst 1230 metres of Plumbing Copper Tube, ranging from 15mm to 133mm, was supplied to the plant room build to connect the system to the other side of the hotel. Alongside the copper tube, 1415 Brymec End Feed and End Braze fittings were delivered.

The Result

Brymec ensured all products were suitable for the purpose and met the requirements of the project.

Due to logistics capability and planning software, Brymec was able to deliver high-quality products within a tight time frame. With the in-house technical team, Brymec also offered technical advice throughout the installation program.

With the size of the plant room to support the luxurious hotel, vast quantities of products needed ordering. With a 99% fulfillment rate, the products required were in stock, and ready for delivery. Having the product in stock gave contractors the confidence that there would be no extra trips back to the site or having to source elsewhere.

Using Brymec products suited to the plumbing & heating systems, the new ‘nerve center’ can supply the whole hotel at full occupancy constantly for 24 hours.

The plant room also cuts 45% of the hotel's carbon footprint. The key to this improvement is the state-of-the-art energy capture system which allows excess heat produced in the plant room to be re-used elsewhere in the hotel.

TV Documentary

Due to the uniqness of this almost impossible project, the build gained interest from around the world. So much so, BBC saw the opportunity to film insight into the extensive project. Filmed over 6 years, the 3-part series follows the work to dig out the five-storey mega basement as well as work done to create the world's most exclusive apartment. You can watch the series here: BBC The Mayfair Hotel Megabuild.

Nathan Gardiner, Key Account Manager, Brymec

“This was a particularly challenging project at a prestigious address and Brymec saw this as a fantastic opportunity to be involved!

We have a long-term relationship with the appointed contractors who knew that we could supply the materials required and were very happy with the quality of the products and services we offer. We worked closely with the project managers to meet their bespoke requirements and were able to offer the flexibility and support to get the job done”