Construction Method Statement Sample - Structures Made Easy

Consulting Structural Engineers and Surveyors Construction Method Statement Sample Client For Ref: 123457

Location xxx Structures Made Easy Limited South Ealing Road London W5 4RL Telephone: 07525 047778 E-mail: support@structures-made-easy.co.uk Principal: Consultant: xxx xxx Copyright Structures Made Easy Ltd. Unless explicitly stated otherwise, all rights including those in copyright in the content of this document are owned by or controlled for these purposes by Structures Made Easy Except as otherwise expressly permitted under copyright law , the content of this document may not be copied, reproduced, republished, broadcast or transmitted in any way without first obtaining written permission from the copyright owner. Consulting Structural Engineers and Surveyors i

Location xxx 1. Scope of Work 1 2. Property type and proximity to other properties and trees 1 3. Soil Condition and Ground Investigation 1 4. Planning drawings with Construction mark up 2 5. Design Philosophy 2 6. Construction Sequence 3 7. Prevailing ground conditions & adverse risks 4 8. Surface Water run-off 4 9. Appendices 5 Consulting Structural Engineers and Surveyors ii

Location xxx 1. SCOPE OF WORK This Construction Method Statement (CMS) is produced for submission to the London Borough of [borough name] in relation to a planning application at [property address], for a front and rear basement extension. The CMS is only to be used for this purpose and may not be reproduced and used for any other property without the express permission of its author, without which, no liability for the accuracy of the contents contained within can be granted or guaranteed. 2. PROPERTY TYPE AND PROXIMITY TO OTHER PROPERTIES AND TREES The property is a mid-terrace dwelling arranged over 3 floors above ground level with a partial lower ground floor. The property is constructed in solid brickwork (no cavity) with suspended timber floors above basement under a slate covered traditional cut and pitched mansard roof. There are no trees in the vicinity of the proposed excavations that would normally constitute further design considerations in accordance with B.S.5837:2012 ‘Trees in relation to design, demolition and construction – Recommendations’. The adjoining property at [neighbouring property address] has very recently carried out a full excavation of the front and rear garden areas to form a new lower ground floor throughout the property. 3. SOIL CONDITION AND GROUND INVESTIGATION The existing ground conditions are noted from the British Geological Records as being Kempton Park Gravels overlying London Clay. Consulting Structural Engineers and Surveyors 1

Location xxx No formal trial pit or borehole log has been carried out at the property given the prevailing conditions whereby there is an existing basement and no obvious hydro-static ground water problems manifest in the existing basement area. Additionally, no pump system was used to enable the excavation to the adjoining basement at [property address] further reinforcing our opinion that the level of the water-bearing strata is below the excavations and intrusions. 4. PLANNING DRAWINGS WITH CONSTRUCTION MARK UP Architect drawings [drawings number] show the existing and proposed basement layouts. Structural drawings [drawings number] show the underpinning sequence and retaining wall sequence and sections. 5. DESIGN PHILOSOPHY The basement design will be carried out following relevant statutory design guidance in the British Standards, namely: B.S.8102:2009 ‘Code of practice for protection of below ground structures against water from the ground’; B.S.8004:2015 ‘Code of practice for foundations’; and B.S.8002:2015 ‘Code of practice for earth retaining structures’. Steelwork support for the existing superstructure will be designed to B.S.5950-1:2000 ‘Structural use of steelwork in building. Code of practice for design. Rolled and welded sections’. Reinforced concrete retaining walls and underpinning will be designed to B.S EN 1992-11:2004 A1:2014. Design loads will be calculated in accordance with B.S.6399-1:1996 ‘Loading for buildings. Code of practice for dead and imposed loads’. Consulting Structural Engineers and Surveyors 2

Location xxx 6. CONSTRUCTION SEQUENCE 1. Excavation will commence at the front of the property with arisings being removed by ‘grab lorry’ on a daily basis. When complete, excavation will continue at the rear of the property with arisings being moved from rear to front by small Bobcat skidsteer machine and/or wheel barrow. The arisings will be lifted from basement level to ground floor for removal using a mechanised conveyor belt. 2. The new retaining walls 1-5 are formed in sequence so that the back of the excavation can be utilised for supporting the back props until the last wall is constructed. Wall 5 will be propped using a sacrificial thrust block cast into the base below the drainage runs to support the inclined props supporting the shutter forming the wall. 3. The existing walls to be retained will be underpinned as necessary using traditional methods in a ‘hit and miss’ sequence as outlined on SME drawing [drawing no.] with underpins typically 1000mm width. Each underpin must be 48 hours old before dry packing. After underpin 3 is formed and dry packed a further 72 hours must pass before excavating for the last underpin 4 is excavated in order to preserve the structural integrity of the other underpins and the party fence wall above. 4. Each underpin is formed using a base and stem. The base is cast first then the stem with continuity reinforcement supplied to tie the two elements together and laterally. 5. Dry packing 75mm thick will be carried out in a specific time sequence to each underpin as outlined in a specification accompanying the underpin installation design to ensure structural stability of the property is maintained throughout the operations. 6. Temporary Works (TW) design to support the front and rear party fence walls and footpath will be designed by a qualified Engineer and followed as excavation proceeds to full depth. Lateral support props will be incorporated at specific depths of the excavation in line with the TW Method Statement. 7. The retaining walls will be formed in elevational sequence with starter bars to connect to the adjacent wall subject to the TW design. 8. The basement slab will be designed to provide lateral support to the finished retaining wall base. 9. Propping for basement wall removal and back propping for ground floor alterations and new steelwork will then be carried out and completed prior to the next item. Consulting Structural Engineers and Surveyors 3

Location xxx 10. The sump pump chamber and below slab drainage for both foul and surface water will then be installed to correct falls leading to the existing main sewer connection for foul and surface water. 11. The new basement slab will then be constructed with soft joints formed around each drainage pipe before pouring concrete. 12. The waterproof membrane will then be applied to the slab and walls in accordance with the warranted design for the membrane and immediately covered with the appropriate level of rigid insulation to protect against damage and for thermal value. 13. The correct thickness of screed will then be applied including any underfloor heating provision to the required floor level prior to applied floor finishes. 7. PREVAILING GROUND CONDITIONS & ADVERSE RISKS Where the ground is found to be stable, excavations can proceed in accordance with the TW design and method statement. Ground water should not present a problem given the absence of hydrostatic ground water arising in the existing basement; however, should ground water ingress occur, a sump pump must be supplied and discharged into a skip or other receptacle to first permit silts to settle before the pumped water is allowed into the below ground drainage system. The primary risk comes from inadequate propping during underpinning and wall removals by not following a clearly defined methodology for Temporary Works. Selection of a suitably qualified and competent contractor is essential combined with professional supervision by the relevant designers. 8. SURFACE WATER RUN-OFF The existing impermeable areas at the front and rear are not materially increased by the construction of the proposed extended basement and therefore do not constitute a net increase of surface water run-off to be considered in design. Consulting Structural Engineers and Surveyors 4

Location xxx 9. APPENDICES Prepared and approved by [SME Consultant] Consulting Structural Engineers and Surveyors 5

Beam over 1 3 4 2 1 3 4 2 Beam over Beam over Beam over Sacrificial Thrust Block Beam over New Column New Column Proposed Basement Existing wall Wall to be properly propped during construction Neighbour's Garden Level Well rammed in dry pack 300 300 RC Retaing wall Patio Level Sub-strata to be passed as suitable by LABC prior to commencement of the work Wall Section Underpinning Section 17 GREEN LANE MS PARSONS Sample Contact:Support@structures-made-easy.co.uk www.structures-made-easy.co.uk · · A3 Structural Details

MS Sample

This Construction Method Statement (CMS) is produced for submission to the London Borough of [borough name] in relation to a planning application at [property address], for a front and rear basement extension. The CMS is only to be used for this purpose and may not be reproduced and used for