New Build Basement Remediation

The Challenge

Within weeks of the project beginning in October 2015, rogue contractors had performed a disastrous basement excavation attempt contrary to the Structural Engineer’s instructions, leaving unsupported banks of earth falling in beneath the street and shutters bursting inwards under the weight of the concrete.

This first attempt, described as “spectacularly shambolic” by Kevin McCloud, more than doubled Joe and Lina’s budget for the excavation from £48k to £100k, and caused months of delays in order to get the project back on track.

  • From the ridiculous - the shocking state in which the basement was left by the first contractor

  • To the sublime - a pristine, innovative and completely waterproof new build basement design

The Solution

Having already contacted Newton Waterproofing Systems to consult on the poor workmanship, Joe and Newton soon determined that if he were to save his home and get it out of the ground, he would need a specialist contractor to actively communicate, collaborate and listen to him as both the engineer and client.

MJ Rooney Construction came on board as contractors in November 2015, and following discussions to determine exactly what was required, modelled the entire project in 4D to ensure that all potential difficulties were solved before work began.

With the right lines of communication in place, work recommenced in late January 2016, with the first challenge being to make safe a 3.5 metre high bank of unsupported earth with sheet piles, before creating a new and waterproof structural shell of reinforced concrete. 

The waterproofing catered for the unique brackets for supporting the suspended slab, which were designed by Joe and the Structural Engineer

Innovative Engineering

With the shell of the structure in place, Newton and MJ Rooney’s next challenge was a much more welcome one, as they created a bespoke waterproofing solution to accommodate Joe’s ingenious design for a suspended reinforced slab that acted as both a floor and a prop force against the lateral pressure from the basement walls. 

This entire slab rested on brackets designed by Joe and his structural engineer, insulating it from the external walls by ensuring minimal contact, and only making contact through insulated blocks with enough compressive strength to take the vertical loading. The design also created a cavity around the slab that can be fully insulated, allowing the slab to be used as a thermal mass inside the building without having to insulate the entire external envelope.

Working closely with Joe, a solution was devised that enabled the continuity of the waterproofing behind the brackets without compromising the structural design.

The innovative ‘floating slabs’ mean that Joe and Lina are able to maximise their 38m2 of land into 83m2 of home

Completing the Grand Design

With a pristine below ground and waterproof concrete structure in place, complete with ‘floating’ slab, MJ Rooney and Newton handed the site over to the next stage in June 2016.

Despite the overall project cost coming in at £250K for Joe and Lina, to overcome such challenges and revive their dream home from a collapsing hole in the ground is a testament to the power of collaboration and teamwork between supplier, contractor, engineer and client.

Related Articles

  • Waterproofing a New-Build Basement

    The waterproofing method adopted for a new-build basement requires careful consideration as failure to make the correct decision can have a major impact on the effectiveness of the system and the potential use of the basement. 

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