CWE/CHM-48/2026-27 SPECIAL REPAIR TO ROOF AND OTHER CONNECTED ITEMS AT BLDG NO P-783 (ASHA SCHOOL) AT CHANDIMANDIR MIL STN UNDER GE CHANDIMANDIR

Dismantling brick tiles or terracing tiles on roof any thickness jointed in any mortar (including cement mortar), stacking serviceable tiles and removal of rubbish off the premises complete all as specified and as directed by Engineer-in-Charge.

Demolition of mud in roofs, any thickness, including plastering and leeping (whether full thickness removed or only a part thereof) including removal of material outside the defence land complete all as specified and as directed by Engineer-in-Charge.

Material and labour for PCC 1:2:4, type B-1 (using 20 mm graded stone aggregates) as in roof padding, roof kerbs rounded or chamfered on edges, 50 mm average thickness, laid to slope as required complete all as specified and as directed by Engineer-in-Charge.

Material and labour for 20 mm thick rendering over roof slab in cement mortar 1:4, finished even and fair including mixing with water proofing compound complete all as specified and as directed by Engineer-in-charge. (NOTE : WPC will be measrued and paid separately as supply only)

Supply only liquid water proofing compound, ISI Marked, complete all as specified and as directed by Engineer-in-Charge.

Supply and fixing Heat Resistant Terrace Tiles (300 mm x 300 mm x 20 mm) with SRI (solar refractive index) > 78, solar reflection > 0.70 and initial emittance > 0.75 on waterproof and sloped surface of terrace, laid over and including 20 mm thick cement sand mortar 1:4 and grouting the joints with mix of white cement & marble powder in ratio of 1:1, including rubbing and polishing of the surface upto 3 cuts complete, including providing skirting upto 150 mm height along the parapet walls in the same manner complete all as specified and as directed by Engineer-in-Charge.

Material and labour for waterproofing treatment to roof complete in the following stages :- (a) SURFACE PREPARATION: Cleaning top surface of roof/ RCC slab using electric wire cup grinder to remove surface imperfections, sharp edges or protrusions at the junctions to achieve a uniform surface profile. Cleaning thoroughly the concrete surface using a high-pressure water jet to eliminate all dirt, dust, oil spillage, laitance, and other contaminants. (b) SURFACE CRACK REPAIR: Cracks on top surface/ RCC slab wider than 1 mm required to be cut and open in V-groove manner (8 mm wide x 6 mm deep) by using mechanical cutter, clean the same and fill with high modulus, moisture curing, silyl modified polymer (hybrid) sealant and allow sealant to air cure for 3 days

(c) ANGLE FILLET TREATMENT: Providing and preparing angle fillet at all vertical up stands and junctions/ corners. Moist the surface with water, apply bond coat prepared by mixing universal repair polymer (URP) and cement in 1:1 ratio by volume and apply using brush, preparing PMM by mixing 1 kg of URP, 5 kg fresh cement and 15 kg graded quartz sand, (i.e. in the ratio of 1:5:15 and preparing angle fillet (gola) of size 50 mm x 50 mm over the wet bond coat and finishing the same followed by moist curing the surface for 48-72 hours complete

(d) RAINWATER OUTLET TREATMENT: Hacking and chipping the surface around the rainwater drain outlet up to 25 mm in depth, applying bond coat of universal repair polymer (URP), in ratio of 1:1 (URP 1 : cement 1) by volume, over the corners and pipe insert outlet gaps, filling the gaps around drain mouth with PMM (Polymer Modified Mortar), mixed with universal repair polymer (URP) 10% by weight of cement, in the ratio 1:3. Providing and fixing 100 mm width, 225 GSM, fiber glass chopped strand mat around the periphery of drain mouth of rainwater outlet, sandwiched with two-component UV resistant hybrid urethane elastomeric waterproof top coat. Applying two thick coats of two-component UV resistant hybrid urethane elastomeric waterproof coating to completely cover the mesh/ fabric and surrounding area. (e) WATERPROOFING APPLICATION: Preparing premix of two-component high-strength hybrid urethane elastomeric waterproofing coating using an electric double paddle mixer at low speed for 2-3 minutes until a uniform blend is achieved without dilution. Applying the waterproofing coating on an SSD (Saturated Surface dry) condition, apply first coat mix at the rate 0.8-0.9 kg/sqm using a lamb's wool roller

Contd.. While the coating is still wet, roll and embed a 225 gm fiberglass chopped strand mat ensuring full bonding without air bubbles or wrinkles and overlap joints by at least 5 cm at end points & allow the first coat to dry for 3-4 hours. Applying the second coat at 90 degrees angle to the first coat at 0.9 kg/sqm once the surface is dry enough to walk on. Additional coats may be applied as required to achieve a forced material consumption to obtain a DFT of 1000 to 1200 microns with minimum material consumption of 1.8 kg/sqm over 2-3 undiluted coats. The coating should terminate below the drip mold on vertical surface. The system complies achieving tensile strength 215 N/mm2 (ASTM D2370 : 2016), Tear strength 2100 N/mm2 (as per ASTM D624), Dynamic crack bridging (EN 13251 : 2016), Shore A hardness: 85, zero water permeability: at 15 bar as per (EN 12390-8: 2019), passes water migration resistance: no leakage, no temperature flexibility: (-) 20 degree Celsius after 1000 hours, UV (ASTM D1970 : 2021), Solar reflectance index : 90 (ASTM E1980 for white), Peel adhesion to concrete (wet condition, 24 hours.), ASTM C794-12, root resistance according to CEN/TS14416-2014 complete all as specified.