128 Repair & Renovation Guide Problems with the roof 4.3 Detached concrete pieces (from the slab) and/or steel reinforcement exposure SOLUTION • Remove the detached pieces, foreign and loose objects and dust from the area. • In places where the steel reinforcement (rebar) has become visible and is rusted, clean it with a wire brush or remove the rust with RUST REMOVER (p. 267). Coat the clean steel reinforcement (rebar) with the corrosion inhibitor RUST FREE POWDER (p. 267). • Depending on the extent of the damage, select one of the resin and fiber-reinforced repair mortars: D-55 (p. 237) for thicknesses of up to 2cm, DS-245 POWER MORTAR RAPID (p. 244) for thicknesses of up to 4cm, DUROFIX (p. 248) or DS-244 POWER MORTAR RESIN (p. 243) for thicknesses of up to 6cm. Repair the areas by covering the steel reinforcement and smoothing the surface. • Waterproof the surface with the waterproofing product of choice, as described in PROBLEM - SOLUTION 4.1. 4.4 Detached or cracked roof coving mortar around the roof area and/or other roof elements (e.g., chimney penetration) POSSIBLE CAUSES Common issue due to subsidence, vibration, earthquake, expansion and contraction or other causes. SOLUTION • In most cases, it is possible to effectively tackle the problem by coating the surface and filling the voids created by the detachment with the two-component cementitious flexible sealant and adhesive DUROFLEX POWDER (p. 249). • In some cases, it may be necessary to completely remove and create them from the beginning, using the resinous and cementitious, fiber-reinforced repair mortars D-55 (p. 237), DUROFIX (p. 248) or DS-247 (p. 244), with the addition of the improving construction resin for mortars DUROMAX (p. 251), in a 1:1 dilution ratio with water. 4.5 Moisture penetration straight through the slab (or the lining installed on it) and formation of mold and black spots on the ceilings directly below the slab POSSIBLE CAUSES The concrete slab, which has not been protected with some form of waterproofing, and its lining, which was possibly installed on the slab without waterproofing it, or without any waterproofing on its top surface, are both vulnerable to moisture penetration. Moisture penetration contributes to both weathering and oxidation of the steel reinforcement (rebar) of the slab but also for that moisture load to transfer to the adjacent or nearby structure elements affecting them, eroding them, and ultimately creating damage. SOLUTION Concrete slab without waterproofing: It is absolutely necessary to waterproof the slab (as described in PROBLEM - SOLUTION 4.1). Concrete slab with failures or damage: It is absolutely necessary to restore all the damage (as described in PROBLEM - SOLUTION 4.2). Lined roof: Related PROBLEM - SOLUTION 6.1 and 6.9. In each of the above cases, after dealing with the problem(s), repair the collateral damage to the structural elements.
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