Purpose of the method statement
The purpose of this method statement is to outline the sequences and methods of works intended to be used for the execution of substructure waterproofing of building basement raft slab & basement walls. The Contractor reserves the right to adapt the methods of execution as contained in this document, modification to this document if required from time to time according to specific site conditions.
1. Scope of works
The scope of works comprises:
Pre Applied System under Raft Slab
Surface Preparations prior to water proofing.
Installation of geotextile slip sheet over the blinding concrete.
Installation of Water Proofing Membrane to basement raft slab.
Installation of geotextile separation layer over the water proofing membrane.
Installation of Swellabel water bar over the membrane in compartment joints.
Protection screed installation over the membrane.
Installation of PVC water bars in construction joints.
Installation of re-injectable hose in construction joints.
Post Applied System on Basement Walls
Installation of Swellabel water bar over the shutter for compartment joints.(prior to casting)
Installation of PVC water bars in construction & Expansion joints.(prior to casting)
Installation of the waterproofing membrane on basement wall.
Installation of protection board for waterproofing membrane on vertical sides.
Installation of re injectable hose in construction joints.
2- DEPENDENCIES AND COMPLIANCE STATEMENT
The present Method Statement is depending on the following approvals:
Material submittal for Waterproofing system for the substructure.
This method statement should be read in conjunction with the following documents:
4 – Method of Work
4.1 General Surface Preparations prior to installation of Water Proofing
For application of water proofing system the blinding concrete surface should be free, loose aggregates and sharp protrusions. Unsound concrete scale if any to be removed and exposed area to be repaired.
The surface should be free from contaminants such as grease, oil, dust, dirt, loose stones debris etc. In general all surfaces to receive membrane to have even finish.
In all internal corners should be provided with 50X50mm angle fillet(cement mortar) is formed. In all external corners chamfers are formed.
4.2 Installation of GEO-FABRIX GT-12 Geotextile slip sheet on Horizontal Areas
Horizontal concrete is thoroughly cleaned to remove all loose particles and dust etc.by main contractor.
A layer of GEOFABRIX GT-12 geotextile layer is loose laid over the cleaned concrete surface. (The geotextile may be mechanically fixed to blinding with nail beyond the concrete limits) All laps of geotetile are spot bonded using contact adhesive at regular intervals. Geotextile is extended beyond the concrete casting limits by 200mm.
4.3 Installation of SOPREMA SOPRALENE FLAM S 180-40 on Horizontal Areas
One of SOPREMA SOPRALENE FLAM S 180-40, 4.0mm thick torch applied SBS membrane reinforced with 180g/M 2 of polyester reinforcement is loose laid over the geotextile slip sheet. The membrane is unrolled and oriented such a way that all side laps will be 100mm and end laps 150mm .
Using a blow torch all laps are fully welded and seamed. The membrane is extended beyond the building limits by minimum 200mm for future lapping with vertical water proofing membrane. At the location of construction joints membrane should be extended beyond the lap length of projecting steel.(approximately 1500mm).
200mm strip of SOPREMA SOPRALENE FLAM S 180, 3.0mm thick torch applied SBS membrane reinforced with 180g/M 2 of polyester reinforcement is then installed on all over laps(side and end) covering the lapped portion using a blow torch. Care will be taken to ensure proper bonding at seam ends, corners etc.
4.4 Installation Of SUPERCAST SW 30 swellable water bars at compartment joints.
SUPERCAST SW30 swellable water bar is installed on edge of each compartments using SUPERCAST SW ADHESIVE over the water proofing membrane.(compartments are designed in co ordination with main contractor)
4.5 Installation of GEO-FABRIX GT-16 Geotextile separation layer on Horizontal Areas
A layer of GEOFABRIX GT-16 geotextile layer is loose laid over the completed water proofing membrane All laps of geotextile are spot bonded using contact adhesive at regular intervals. Geotextile is extended beyond the concrete limits by 200mm. At the location of Swellable bar geotextile is discontinued for direct contact of raft slab concrete with water bar.
4.6 Application of Protection layer (screed) on horizontal membrane
Once installation of swellable water bar & geotextile is completed, Suitable timber formwork is then placed along the compartment so that when protection screed cast on the membrane water stops are not covered in the screed.(main contractor)
A layer of polythene sheet is laid over the membrane and 50mm thick cement sand screed is cast over the membrane(main contractor) Polythene sheet is discontinued at the location of swellable bar direct contact of raft slab concrete with water bar.
4.7 Installation Of SUPERCAST REARGUARD R pvc water stop at construction joints
SUPERCAST REARGUARD R externally placed PVC water stop is installed over the protection screed. At all change in direction and angles water stops are butt joined using PVC heating element. (Location of water stop will follow the construction joint schedule)
4.8 Installation Of SUPERCAST PREDIMAX INJECTION HOSE in raft construction joints.
In all construction joints in raft slab, once the first stage casting is completed SUPERCAST PREDIMAX INJECTION HOSE is installed. The hose system is connected with a network of junction boxes(supplied in the same kit) placed at every 10mts interval on basement wall for future maintenance of water proofing system.
4.9 Installation Of SUPERCAST SW 30 swellable water bars at compartment joints vertically
SUPERCAST SW30 swellable water bar is installed on the wall form work using nails on each compartments prior to casting of wall concrete.(compartments are designed in co ordination with main contractor)
Once the wall shutter are removed exposed side of SUPERCAST SW30 is cleaned and SUPERCAST SW ADHESIVE is applied and 200mm wide piece of 1.5mm self adhesive membrane is installed on it . At the location of expansion joint self adhesive membrane of approximately 250mm width will be installed over the water stop covering swellable bars on both side.
4.10 Installation of SOPREMA SOPRALENE FLAM S 180-40, 4.0mm thick waterproofing membrane on vertical basement wall
Cold applied primer IMI CONCRETE PRIMER is applied on the prepared wall surface at the rate of 250-300g/M 2 depending on the porosity of the substrate. Primer is applied evenly on the substrate using roller or brush. Primer is allowed to dry for about 6 – 24 hrs depending upon the weather conditions at the time of applications. Care will be taken to avoid flooding of the primer. Primer is not applied over the SUPERCAST SW 30 swellable water bar.
240mm wide strip of SOPREAM SOPRALEN FLAM S 180 3.0mm thick torch applied SBS membrane reinforced with 180g/M2 of polyester reinforcement is applied on all internal corners over the angle fillet and bonded to the primed concrete surface by torching.
One layer of SOPREMA SOPRALENE FLAM S 180-40 4.0mm thick torch applied SBS membrane reinforced with 180g/M 2 of polyester reinforcement is applied by heating the lower surface of the membrane by torching and bonding to primed concrete surface as the membrane is hot. On horizontal areas membrane is extended over the previously laid horizontal membrane and torched to form a form a water tight seal the vertical area membrane.
The membrane is fully bonded to the substrate by heating with a blowtorch with 100mm side laps and 150mm end laps. All side and end laps will be fully torched and seamed. Care will be taken to ensure proper bonding at seam ends, corners etc.
200mm strip of SOPREMA SOPRALENE FLAM S 180, 3.0mm thick torch applied SBS membrane reinforced with 180g/M 2 of polyester reinforcement is then installed over all laps covering the lapped portion using a blow torch. Care will be taken to ensure proper bonding at seam ends, corners etc.
Water proofing membrane is terminated into the preformed groove at the ground level.
4.11 Installation of PROTECTAR 60 protection board over Waterproofing Membrane on vertical areas.
The membrane is protected using IMI PROTECTAR 60, 6.0mm thick pre moulded bituminous protection board thermally bonded to water proofing membrane by slightly warming the lower side of the board.
4.12 Termination of Protection board on Vertical Basement Wall.
Protection board is terminated by 80mm wide, 0.7girth aluminium strip mechanically fixed to the basement wall using screws having special rubber washer. The top of the strip is sealed with approved sealant.
4.13 Installation of SUPERCAST PREDIMAX INJECTION HOSE SYSTEM in construction joints in the wall
In all construction joints in basement wall SUPERCAST PREDIMAX INJECTION HOSE is installed after completion of first pour. The hose system is connected with a network of junction boxes terminated in basement wall for future maintenance of water proofing system.
5- PRECAUTIONS AND SAFETY MEASURES
- All site personals will be briefed about the safety regulations, requirements and their importance.
- Primer is a flammable liquid with flashpoint around 65 0 C precautions will be taken handling and storing of primer,
- Primer to be used in well ventilated areas.
- In the absence of natural ventilation forced ventilation arrangements will be made.
- Naked fires, smoking and sparks should not be allowed near the storage area or area in use.
- While handling the primer care will be taken to avoid contact with foodstuffs, eyes and mouth.
- The primer containers will be kept properly closed during and after use.
- Protective clothing, hand gloves, goggles etc to be worn at site all the time.
- Fire extinguishers to be kept always at the proximity of works.
- Blow Torch
- Gas Cylinder
- Rubber Hose
- Hand gloves
- Cutting knife