Standards for a Two to Three Story Residential Concrete Structure

Works should conform to the current National Building Code of the Philippines, National Structural Code of the Philippines, National Plumbing Code of the Philippines, and National Electrical Code of the Philippines.

First off, make all formworks strong enough for all types of load. It should be constructed efficiently – supported and horizontally and vertically so as to retain shape and form. Joints should be proofed against leakage and seepage. It should be strong enough to allow easy removal in pre-set sequence without undue damage to the concrete set. Materials should be set correctly to the accurate line and levels and it should have perfectly flat surface.   It should be made of the lightest possible materials. It is preferred that form materials should be easy to find and should be re-usable such as phenolic boards supported by metal tubes or rods. It should not warp, shrink, or bloat when exposed to all kinds of weather. Its base should also be firm and solid.

When removing the formworks, start with the vertical faces of the walls, beams, and column sides. Followed by the forming soffit of slabs, then finally the forming soffit of beams, girders and other heavy loads.

Footings should stand and bear on undisturbed on firm natural earth or compressed fill that can withstand supporting a design pressure of 2,000 PSI. Foundations concrete should have a 28-day compressed strength of 3,000 PSI. Concretes that are always exposed to weather should be low density allowing micro bubbles to 5% (+/- 1%) through an admixture that conforms to American Society for Testing and Materials (ASTM) C-260. Concretes works should follow Association of Construction Inspectors (ACI) 301 (Specification for Structural Concrete Buildings). Reinforcing steels should meet ASTM A-515, Grade 60. If otherwise specified, the following cover should be observed for reinforcements: a. Concrete cast permanently exposed to earth – 75mm; b. Concrete exposed to earth and weather – 20mm Ø through 36mm Ø – 50mm, 16mm Ø bars smaller – 38mm. Reinforcing marked continuous on the plans and designs should be lap 40 x Bar diameter on splices unless otherwise specified.

Cast-in-place Concrete mixes should meet ACI 301 – using Portland cement that conforms to ASTM C-150 of C-595, aggregate conforms to ASTM C-33, and admixtures conforms to ASTM C-494, C-1017, C-618, C-989 and C-260. Ready mixed concrete should meet ASTM C-94. It should also conform to the following strengths, slump and water/cement ratio requirements:

Supervising engineers may use admixture to produce easy flowing mixture. The maximum slump should not go beyond 10 inches. The supervisor should submit test results of the proposed concrete mixes together with the manufacturer’s technical data before pouring. Concreting shall meet ACI 301 (Specification for Structural Concrete Building). Rebars shall meet ASTM A-615 – Grade 60. Welding of reinforcing metals should meet AWS D1.4. Epoxy coatings should meet ASTM A-775. Steel reinforcements should be set and placed before pouring the concrete, except when vertical dowels for walls reinforcers are “floated”. Do not pitch bent bars that are partially embedded in hardened concrete unless specifically indicated or approved. Steel reinforcers, including the hooks and bends, shall be specified to meet with ACI. Further, steel reinforcers specified as continuous should lap with type 2 Lap Splice unless otherwise specified. Edgings of exposed surfaces should be cut away at a right-angle edge or corner 20mm unless otherwise specified. Do not remove formworks until the concrete is at 90% of its 28-day compressive strength curing.

Masonry works should meet the “Specifications for Masonry Structures (ACI 340.0-95)” – published by the American Concrete Institute. Hollow load-bearing masonry units should meet ASTM C-90, Grade N-1 and should be of lightweight aggregates. Minimum prism compressive strength (f’m) should be 1,550 PSI at an age of 28 days, as set by the unit strength as per ACI 530.1. Put grout on all bond beams and reinforced cells solidly. Grout should meet ASTM C-475 and should be in a minimum 28-day compressive strength curing of 2,500 PSI. Steel reinforcers should meet ASTM A-615, Grade 60. Fabricated reinforcer bars that are to be hooked or bent should Provide a minimal lap of 48 x bar diameters on all splices unless otherwise detailed. Mortar should meet ASTM C-270, Type S. All mortar should meet the “Proportion Specification” of ASTM C-270 and be made with Portland Cement/ Lime (Non air-entrained). Unless otherwise set, all walls should be laid in running bond. Put rebar dowels from foundations to match vertical reinforcement size and spacing. Dowels must be 90º hooked and lapped with the first lift of reinforcing. Place horizontal bond beams with continuous reinforcers as specified. Finish all horizontal reinforcers at the control joints except for the bond beams at the bearing elevations. Provide bond beam lintels and brick shelf angles above all wall openings for door and windows. On masonry reinforcements, always use 10mm Ø vertical bars spaced at 600mm O.C. and 10mm Ø horizontal bars per 3 layers of CHB unless otherwise specified by the structural engineer.

All Structural Steel must meet the 1994 edition of the Load and Resistance Factor Design (L.R.F.D.) (Manual of Steel Construction) of the AISC. When otherwise designed, all materials shall meet the following ASTM requirements:

Connections must be shear type – factory set for the factored shear forces as per design to meet American Institute of Steel Construction (AISC) specifications for load and resistance factors. Bolts must be minimum of 20mm in diameter unless specified otherwise, bolts must be shear/bearing type and “snug-tight”. Welding works must meet American Welding Society AWS D1.1 using E70xx electrodes, unless specified otherwise. Make continuous minimum sized fillet welds per AISC requirements. Filler materials must be a minimum yield strength of 58 KSI. If “Continuous Chord” angles are indicated, you must provide a continuous butt weld or full penetration weld at the splice points. Steel fabricators may submit an alternate bolted connection detail. Holes must be drilled or punched. Slotted holes must have smooth edges. Hole burning and cutting of torch at the site will not be allowed. If not otherwise specified, structural steels must be double coated with Type I (Red Oxide) Paint that meets The Society for Protective Coatings (SSPC) 15-68. All temporary guying and bracing must be done with structural steel erectors. Columns, anchor bolts, base plates, etc. must be designed for the final completed condition. Steel erections for columns, anchor bolts, base plates, must be duly designed. Protective paintings that are damaged during transit, erecting and field welding processes must be restored on field and must match the factory applied coatings.

Exterior walls must be plain cement finished with a thickness of 1/2 inch. Interior walls must also be plain cement finished with a thickness of 3/8 inch. Glazed tiles must be properly placed on specified locations indicated in the design. Paints must be flat latex. Painted walls and columns must be treated first with concrete neutralizers then with a primer and finished with double coats of paint. Openings on walls must be properly sealed. Moldings, if provided must be made as indicated in the plans and must be located accordingly.

Flooring finishes must be as indicated in the design: a. Patio, Service – 3000mmx300mm Unglazed Terracotta Tiles; b. Living, Dining, Kitchen and Bedrooms – 300mmx300mm glazed ceramic tiles; c. Toilet and Baths – 300mmx300mm unglazed; d. Stairs, Roof Deck- 300mmx300mm non slip Ceramic Tiles. Tiles must be grouted.

Ceilings must be 4’x8’x1/8” fiber cement with a first coat of flat latex primer and finished with two coats of the same. Lighting fixtures must be of the design specified by the architect or owner. Ceiling height must be a minimum of 2.4m.

Panel Doors must be wood with the option of a customized or manufactured design that is approved or chosen by the owner. Windows must be at least made of aluminum frames customized to size by the chosen manufacturer, or Unplasticized Polyvinyl Chloride UPVC if required by the owner. Window and door heights must be minimum 2.10m. Window sills must be 900mm from finished floor, kitchen window sill at 1.3m and toilet and bath window sill at 1.5m.

Plumbing lines must be concealed as much as possible. Pipes must not be embedded in structural members unless otherwise designed or allowed. Run all horizontal piping in perfect alignment and at uniform grade of not less than the slope of 1:50 for sewer lines and 1:100 for drainage lines. Floor drains must be vented individually. Cleanouts must be flush mounted to wall and must have cover caps. Do not install floor cleanouts except at lines on grade and service areas not service to traffic. Sanitary sewer pipes and fittings must be Atlanta polymerizing vinyl chloride (PVC) pipes. Provide vent pipes and vent stack thru roof as specified. Place gate valves on all water supply lines to fixtures. Individual branches to fixtures or groups of fixtures and / or equipment must be placed with air chambers or capped with vertical pipe extensions. Plumbing works must be under the direct supervision of a licensed Sanitary Engineer or Master Plumber.

Electrical materials must be brand new and installed in applications for which they are intended. Metallic conduits, cabinets and related equipment must be properly grounded and bonded by means of copper straps connected to the copper grounding rod. Size of conductors must be minimum of 3.5mm THHN in 20mm Ø PVC unless otherwise required by the electrical engineer. Exposed conduit runs must be parallel to or perpendicular with building lines supported by anchors or clamps. The engineer shall verify and orient the actual location of the concrete terminal pole for connection to the power supply, telephone, & CATV services. Switches must be rated 15A, 250V and shall not carry a load greater than 50 Amperes. Light switches must be placed for operation on vertical position. Duplex receptacles must be rated 10A, 250V. Special purpose outlets must be rated 15A or 20A, 250V or as required. Electrical works and installations must be done under the direct supervision of a duly licensed Electrical Engineer or Master Electrician.