Knebworth House is a historic manor house built in Tudor Gothic style around a central square court and surrounded by a historic deer park covering over 250 acres.
The building had a history of movement, having undergone remodeling and restyling by generations of the Lytton family. Monitoring of visible cracking and progressive movement to the to the north-west turret had been ongoing for almost 30 years. More recent inspections had highlighted some considerable advances in movement on the turret showing cracking increases of 8.5mm to just under 16mm in places.
Investigations carried out to the south side of the turret identified a range of possible causes for the movement. A series of boreholes established the ground conditions and a trial excavation uncovered the existence of a considerably shallower turret foundation as compared with foundations to the existing main building and the adjacent cellar.
Geostructural Solutions was appointed to carryout the structural works to permanently stabilise the turret. Our solution involved increasing the depth of the turret foundations to the same depth and bearing stratum of the main house, through. The increased depth foundations would be constructed using hand excavated underpinning techniques.