Cellar and Basement Underpinning in Liverpool

Which Liverpool homes have cellars?

Cellars are common in Victorian and Edwardian houses across Liverpool and the Wirral, from bay-fronted terraces and villas in Aigburth to larger houses in Oxton and Claughton around Birkenhead. Some run under the whole ground floor; many sit only beneath the front rooms, so the house has deep foundations at one end and shallow footings at the other. That change in depth is one reason cracking in these houses can show up at the junction between the cellar walls and the rest of the building.

Cellar walls do more than hold up the house. They also retain the soil, and any water in it, on the other side. That makes them part foundation, part retaining wall, and it explains why problems can come from several directions.

What problems do we see with cellar walls?

• Cracking through the wallStepped or vertical cracks, sometimes continuing up into the room above, which may or may not mean continuing ground movement.
• Bulging or leaningA wall pushed inwards by soil and water pressure, or one that has lost lateral restraint from the floor above.
• Movement at a change in depthCracking where a part-cellar meets shallow footings under the rear of the house.
• Failed openingsCracked brickwork over old coal chutes, windows or doorways where a lintel has corroded or rotted.
• Disturbed groundWet or softened soil near the footings, often linked to a leaking drain running past the cellar.
• Floor lowering plansOwners wanting more headroom, which means the walls must go deeper before the floor can.

Damp in a cellar is very common and is not, on its own, a sign of structural movement. It does need to be thought about in any design that alters the walls or floor, but waterproofing is a specialist subject of its own.

When does a cellar actually need underpinning?

Less often than people fear. If cracking is old and stable, the engineer may only specify crack repair, perhaps with crack stitching to restore the masonry. If a wall is bulging because it has lost restraint, the answer may be ties or straps rather than deeper foundations; see bowing wall repair. If a drain has softened the ground, fixing the drain comes first. Underpinning is the right tool when the cellar walls are bearing on ground that keeps moving and the cause cannot be removed, or when the floor is being lowered and the walls must go deeper to stay supported.

How is cellar underpinning carried out?

1. Inspection and investigation. A structural engineer survey looks at the walls, floor, openings and the house above. Trial holes may expose the footings, and drains near the cellar may be surveyed.
2. Design. The engineer specifies the method, depth, bay sizes, sequence, any temporary propping and how the new floor and walls tie together.
3. Permissions. We submit the Building Control notice. A party wall surveyor deals with notices to neighbours where the Act applies; our party walls and underpinning page explains how that usually works.
4. Preparation. The cellar is cleared, services are located, and temporary supports are installed where the design needs them.
5. Underpinning in bays. The walls are underpinned in short sections in a hit-and-miss sequence, so no long length is ever left unsupported. Each bay is inspected before concrete is placed and then dry-packed to the old footing.
6. Floor and finishes. Once the walls are complete, the floor is formed as designed, and the engineer and Building Control sign off the structural work as applicable.

Most cellar work uses mass concrete underpinning, because the excavation is already partly done and the work happens from inside. Where firm ground is deep, the engineer may consider other methods. Restricted access down narrow stairs and through small coal-chute openings shapes what plant can be used, and much of the digging is done by hand.

Is your insurer involved?

If cracking in a cellar is new or growing and you think the house may be subsiding, contact your buildings insurer first. The insurer and its engineer decide on investigation and repair, and whether underpinning is needed at all. Floor lowering for extra space is your own project and is not normally an insurance matter.

What affects the cost of cellar underpinning?

The length of wall, the depth to suitable ground, access into the cellar, temporary propping, groundwater, party wall involvement, Building Control, drainage work and what finishes are needed afterwards. Floor lowering adds the removal of spoil, which from a cellar is often carried out by hand. We price only once the engineer's design is ready; the underpinning cost guide explains the published national figures and the factors behind them.

Cellars are one of the more specialised corners of underpinning in Liverpool, and the planning matters as much as the digging.