Cavity wall Method statement

BLOCKWORK CAVITY WALL

1.0 OBJECTIVE

1.1 Is to define the method of construction and quality requirements of blockwork cavity walls for the contract no GTC.101/ED/01 Engineering, Procurement, Installation and Commissioning (EPIC) of Ras Laffan Utilization Project –Buildings and utilities and support service Phase 1-Utilities.

2.0 SCOPE

2.1 Blockwork Cavity wall for the buildings in Service Base Area, Service Berth and Telecom building.

3.0 REFERENCE

3.1 Project Approved Drawings

3.2 Qatar Petroleum Standard Specification for Civil Works Vol. I, Section 4

3.3 British Standards BS 6073, BS 4027, BS 12, Bs 1200 table 1, BS 4887, BS 1243           Table-3, BS 743 type-C, BS 3416-type 1, Class A

4.0 PROCEDURE:

4.1 BLOCKWORK CAVITY WALLS WITHOUT INSULATION

• Approval shall be taken from QP for the materials – Blocks, cement mortar, wall ties, DPC, insulation board if any prior to commencement of work. Sample of all the materials shall be available at site for QP verification/reference at all times.

4.1.2 Settingout and marking for the cavity walls shall be done as per approved drawings. QP approval shall be taken before proceeding with construction work.

4.1.3 Cavity wall shall be constructed of two leaves of blockwork, separated by a cavity and united by building wall ties spaced at 900 mm horizontal centers and 450 mm vertical centers and staggered vertically. Wall ties shall be built into each leaf a minimum depth of 50 mm. Additional ties shall be provided at the vertical edges of the openings built in at 450 mm vertical centers within 150 mm of the cavity closing.

4.1.4 Ties shall be placed as the work proceeds and set with a slight slope towards the external leaf. One leaf shall generally not rise higher than 450 mm above the other.

4.1.5 Cavities shall be kept clear of all mortar dropping by means of a temporary wooden lath laid on top of the wall ties and raised as the work proceeds. Temporary openings shall be left at the base of cavity walls so that the bases of the cavities may be cleaned free of mortar dropping. The temporary openings shall be properly closed.

4.1.6 Cavities shall be closed at the free ends of walls or at the sills and jambs of openings with solid blockwork minimum 100 mm thick bonded to one skin.

4.1.7 In external cavity walls, vertical damp proof course materials shall be built in between the closing and the other skin, to the widths indicated on the drawings.

4.1.8 Request for Inspection shall be applied to QP for inspection and approval during construction. 

4.2 CAVITY WALLS WITH INSULATION.

4.2.1 Wherever cavity walls are required to be insulated, the insulation shall be installed as the wall is constructed. One skin of the walling shall be built upto a height of 450 mm and a 450 mm high insulation board placed against it and held in a position with galvanized nails driven into the mortar joints. The second skin of wall shall then be built and cavity ties placed in position on top of the insulation and bedded in the joint mortar. The insulation shall be carefully notched to receive the wall ties.

4.2.2 The next and subsequent insulation boards be installed in the same manner, care being exercised to ensure that horizontal and vertical joints are closely butt jointed together and the insulation is carefully notched around and closely fitted against opening, pipes and the like passing through the cavity walls.

4.2.3 All the inspection requirements are as above.

  5.0 RECORDS:

• Inspection Reports

• Check list