Repair of Damaged SFRM After Rough-In
After mechanical, electrical, and plumbing rough-in, a 4-ft² area of SFRM on a W14x90 column is damaged. The approved design requires 1-1/2 in. of SFRM for a 3-hour rating. The existing material is 1-1/2 in. thick and appears sound except at the damaged area, where bare steel is exposed and the edges of the remaining SFRM are crumbly. Paint overspray and construction dust cover the steel. The applicator proposes to spray new material directly over the area without removing loose material, because 'the new material will encapsulate the old.' The product's repair instructions require removal of loose and damaged material to sound material, cleaning of the substrate, a bonding agent where recommended, and application in lifts not exceeding 1/2 in. Ambient temperature is 50°F and the substrate is dry. The inspector must specify the repair procedure, acceptance criteria, and documentation.
1. Evaluate the applicator's proposal to spray over the damaged area without removing loose material.
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The proposal should be rejected. Loose, crumbly SFRM and construction dust or paint overspray prevent a reliable bond. New material sprayed over the old surface would not encapsulate the defect; it would create a patch that depends on the weak interface and could delaminate later. The product's repair instructions are controlling and require removal to sound material, substrate cleaning, and a bonding agent where recommended. The inspector should require the contractor to cut back or remove the damaged and loose material, clean the exposed steel and the edges of the sound SFRM, and prepare the surface before any new material is applied. The repair should not proceed until the inspector has verified the preparation.
2. Describe the repair procedure and acceptance criteria.
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The contractor should remove damaged and unbonded material to sound SFRM, clean the exposed steel of dust, oil, and paint overspray by the method acceptable to the manufacturer, and apply the specified bonding agent if required. The new SFRM should be applied in lifts not exceeding 1/2 in. and built up to the required 1-1/2 in. thickness, with adequate cure time between lifts. Acceptance should include a visual check for voids, cracks, and unbonded edges; thickness measurements meeting the 1-1/2 in. minimum; and adhesion/cohesion testing if required by the project specification or if the repair is large enough to warrant it. The repair should blend into the surrounding material without leaving a feather edge that can lift. If the repair fails thickness or bond checks, additional removal and reapplication are required.
3. What documentation should the inspector require for the repair?
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The record should identify the column, the damaged area and dimensions, the date of repair, the material and batch, the surface preparation method, the bonding agent and batch, and the environmental readings at the time of application. The inspector should record the lift thicknesses, final thickness readings, visual observations, and any adhesion test results. Photographs or sketches may be used to show the repaired area and the extent of removal. The daily report should note that the repair was made after rough-in and that the contractor followed the product's repair instructions. The final inspection report should cross-reference the discrepancy report, the corrective action, and the passing verification so that the repair is closed out in the project records.