Method Statement

Stage 1

For suspended floors, remove the floor boards. Skirting boards are not normally removed so if a planking board goes under the skirting board, an area of approximately 2.5m2 will be cut with a circular saw. All lifted materials are carefully set aside for refitting.

In the event of a floor covering being ceramic tiles or concrete screed then the excavation process begins with a heavy duty breaker to the marked circumference of the hole. The use of the breaker will continue until the sub soil is reached. In the event that the sub floor is a beam/block structure or timber floor joists, the necessary beams/joists will be cut by using a disc cutter/hand saw. Upon removal of the cut beams/joists, the existing remains of all sides of the beams/joists will be supported by a concrete lintel or timber support on pads of Thermolite blocks and concrete.

Stage 2

The excavation of the sub soil can begin. The process is hand digging a spit section and removal of the spoil to a skip. This method is used down to approximately 1 metre without the need for shoring unless the team leader deems it essential. The use of a mini breaker with a point/chisel/spade may still be necessary if the sub soil ground  conditions  demand. At approximately 1 metre deep a form of shoring will be constructed. The shoring will be sectional corrugated steel sheets with 6 sections forming a ring at 750mm effective height. The sections are dropped down into the hole as the excavation progresses. As the excavation deepens all spoil is removed from the hole by bucket and hoist. The extraction of sub soil will continue for approximately 2 to 3 days. There may be a need to pump out water from the hole during the excavation and this process will continue until completion of the dig if necessary. The team leader has the ultimate say as to whether the excavation target can be reached safely without risk to the health and safety of his team. This may mean that a project target is reduced thus meaning that a finished cellar of a lesser depth may be achieved. The project manager will keep you informed. This is an extremely rare occurence.

The fitting of the cellar (Full Installation and Fit Only Installation)

1. The team will check site datum, in particular the finished floor level and that the hole is at the right depth and shape.

2. Upon completion of the excavation a geotextile base disk will be laid in the ground. A 50mm thick sharp sand blinding will be poured into the geotextile disk. This will prevent any 'sharps' rising in the ground in a high water table environment and causing damage to the butyl liner. A geotextile lining sheet will be inserted into the excavation.

3. A heavy duty Butyl tanking liner will be fitted inside the geotextile and both will be lamped/supported at the top of the hole using scaffolding planks as a safe working platform, thus keeping the bag taut.

4. A base slab of concrete, specified by the engineer, will be poured into the bag and levelled.

5. The modules are lowered into the bag via supports and one man will be at the bottom setting out/fitting the modules and step modules. The top ring is fitted just below finished floor level and one half of the ring is covered by soffit boards.

6. The ring/void outside the bag is then back filled with wet concrete and strux fiber reinforcement (refer to Strux engineering bulletin for Strux technical specification).

7. The plastic ventilation pipes are fitted. One length of pipe is fitted down the centre column and one pipe is fitted through a pre cast hole in the flat soffit board. Both pipes are then directed to the nominated outside wall (in a fit only project, pipes are already channelled beneath floor level to this wall by the contractor). The pipes will rise up either the inside or outside of the wall with any joints being solvent welded. The pipe will exit the wall via a hole prepared with a 55mm core drill. This is then sealed and made weather tight. One pipe will be raised to 0.50m height and the other pipe will be raised to a minimum height of 2.0m. The pipes will be clipped to the wall and the open pipe will have rodent guard covers fitted.

8. Electric bulk head lights will be fitted to the top and bottom of the cellar. They will be linked and a switch fitted at the head of the cellar. A feed for connection to an existing ring main will be linked from a socket to the cellar light switch and all cabling will be routed in conduit underground. A fused spur may be fitted where applicable. LEDs are also available for the White Cellar.

9. The trap door is fitted onto the open half side of the cellar. It is set on a 25mm bed of mortar and the finished detail inside is haunched in to leave a smooth finish.

10. The door is tested for opening and closure.

11. Thereafter the floor area around the cellar is reconstructed as directed and in accordance with the order specification.

12. The site is then cleared of waste and cleaned/washed down as required.

13. All protective coverings are removed and disposed of.

The sequence for point 5, 8, 9 is different for a round glass trap door.

The team leader will fill in a ’job completion form’ illustrating any differences to the pre order requirements, risk assessment variations, incidents/accidents, snags required, difficulties, incomplete items or other. At stages through the construction process the Project Manager will have visited the site.

Also we will have requested that the local authority Building Inspector visits the site to ensure approval of the construction method.

Following Trades

• The trap door must be left open for a minimum of two weeks to allow the cellar to dry out.

• Do not allow rubbish and site debris to fall into the cellar – this increases the risk of the cellar being damaged.

• Under floor heating.

If there is under floor heating in the same room, then  NO UNDERFLOOR HEATING pipes to be laid within the circular area  of excavation PLUS 300mm all round. Vent pipes are to be fully wrapped and insulated if shallow, or may have to run under the slab. NO OTHER SERVICES SUCH AS HOT WATER PIPES TO RUN ACROSS CELLAR AREA OR VENT PIPE RUN.

• The trap door should remain protected until the after sales visit is complete.