A retro-fit basement is a basement under a house where there was not one before. This represents structural, waterproofing and construction challenges. Whilst the excavation occurs the whole house above, along with neighbouring houses must be supported to prevent collapse.

Waterproofing was a challenge as this property already had a small basement which needed to be incorporated into the new basements waterproofing design. Construction wise, working and making significant changes to houses that are 150 years old is always very tricky as unique problems are always around the corner.

Excavation begins for a new light wellNew external stair case being excavatedCreation of opening for new external door to basementRetaining wall for new light well ready for concreteReinforcing for underpinning wallsUnderground drainage leading to a sump for the waterproofing systemSump located in new external stairwellNew window created to allow natural light, floor reinforced ready for concreteSteel beams and new blockwork creating a new window and escape route to the light wellNew window aperture following the bay window aboveNew internal wallsCavity drainage membrane applied to all wallsAll walls waterproofed and floor cleaned ready for flooring membraneAll joints in cavity membrane taped and sealedNew ceiling joists installed and insulated, Door way to new toilet createdNew bespoke sash windows installedInternal walls, creating a bathroom area for the new self-contained apartmentUnderfloor heating on top of insulationNew external stairwellWaterproofing in new stairwellNew external staircaseNew external staircase with render being applied for a finishTile finish to new external stairsTiled finish to new external stairsExternal staircaseTwo new doorways in external stairwellRailings and hand rail for new staircaseCover for new light wellNew living room spaceBasement and cellar conversionsNew bay window to allow natural lightNew kitchenetteStudio apartment with living areaRetro-fit basementStylish decorations & lighting throughoutRetro-fit basement apartmentEntrance hallwayNew fireplace on ground floor above

Build Method

Beautiful Basements was asked to take the lead on a retro-fit basement project in central Leicester to create a brand new, self-contained apartment, and make liveable. During the project the whole house needed to be supported and all works be carried out around these supports to avoid disaster. During the design phase it was very clear to all that a basement expert was required to carry out all the works, and so Beautiful Basements was the natural choice.

The first step was to excavate externally for the new stair and light wells. Once formation was reached, the concrete slabs could be cast and the excavation could begin under the house. Done in one meter sections, the existing walls were underpinned, and the central spoils were removed, creating a concrete walled basement. The new concrete floor was tied into the new walls and the ground floor supported above with new steel beams. Once the shell had been finished the basement could be waterproofed and finished as any normal conversion.

Waterproofing Method

Type C – Drained cavity protection

When designing existing basement waterproofing systems, the substrate of the building needs to be considered. This project involved the conversion of an old pub.

The existing basement in the old pub was traditional brick walls and concrete floor, allowing for a straight forward design & installation. According to BS8102:2009, the most reliable form of existing basement waterproofing is a Type C – drained cavity protection system.

All walls and the floor were lined with a cavity drainage membrane (CDM). These membranes were linked to sump chambers via a combination of preformed perimeter channels and underground pipes with inlets cut off at floor level. Within the sump are two pumps and a high-level alarm. This system is designed to catch any water, direct it to the sump and discharge it automatically. Flushing and maintenance points were installed to allow future servicing of the system.

The waterproofing in the existing basement was designed by Structural Surveyors in Structural Waterproofing (CSSW) in accordance with BS8102:2009

All waterproofing materials were supplied by Triton Systems Ltd

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Location: Leicester City
Completed: 2019