Cladding remediation

How does Cladding remediation work, step by step?

1. 1

   Step 1: Establish the scope from the assessment and the record set

   The starting point is the fire engineer's assessment of the external wall and whatever record set exists - original drawings, warranty and handover information, records of previous repairs and alterations, and any earlier investigations. These are read together to define what has to be remediated and what can remain. The standard the rebuilt wall must reach comes from the fire engineer and the building safety regime, and it is fixed before pricing so that everyone is bidding the same job. Where the record set is thin, that uncertainty is priced and programmed as uncertainty rather than assumed away - typically as a provisional sum with a defined opening-up allowance.

2. 2

   Step 2: Open up and survey the wall as it really is

   Intrusive openings are made at locations agreed with the fire engineer - commonly a dozen to several dozen on a single block - chosen to sample the variety of the building rather than the easiest spots - different elevations, different levels, and every junction type: window heads and reveals, balcony connections, compartment floors, parapets, corners and service penetrations. Every layer, fixing, cavity barrier and void is recorded as found and reconciled against what the assessment assumed. Where no scaffold is up yet the openings are made off rope access or a MEWP and made good and weathered the same day. This step is where the real job is defined, so a change control route has to exist before it starts, because it will be used.

3. 3

   Step 3: Set up the building: residents, access and the temporary fire strategy

   A resident liaison plan comes before the scaffold. Residents get a named contact, notice of what happens when, and a booking system for any work needing entry to a flat - and flat access, not trade productivity, becomes the critical path. One liaison officer to something like 100-150 flats is a common ratio, and on a large block it is a full-time team rather than a part of somebody's job. In parallel the fire engineer sets a temporary fire strategy for the works, agreed with the fire service and the responsible person, covering detection and alarm arrangements, the evacuation strategy while the wall is disturbed, and protection of escape routes. That strategy is a living document reviewed at every change of stage, not a one-off submission.

4. 4

   Step 4: Design, erect and control the access

   Scaffold to a high occupied building is significant temporary works: it is designed for the loads and the exposure, and it has to be tied into a wall that is being dismantled as the job proceeds, so the tie strategy is designed around the strip sequence rather than fixed at the start. It is also slow - erecting to a fifteen- to twenty-storey block commonly takes two to four months, and it then stands for the whole of the works. Sheeting, encapsulation and any temporary roof have to satisfy the fire engineer. A scaffold outside occupied flats is also a security problem and a privacy problem - alarms, anti-climb measures, screening and lighting are part of the design, not extras. Where scaffold is not viable, mast climbers or rope access change the sequence and the storage arrangements entirely - a mast climber goes up in weeks rather than months but carries far less material to the face at a time.

5. 5

   Step 5: Strip, repair and rebuild the wall

   Removal is done in controlled zones - commonly a bay or two wide and a few storeys high - so that the building is never widely open at once, and each zone is worked through to a weathertight, closed state before the next is opened. A rainscreen strip produces a large volume of light, bulky waste, so chutes, segregated skips and frequent collections are planned rather than improvised. Behind the cladding the crew commonly finds work that was not in the scope - substrate damage, corroded fixings, structural defects, water ingress, missing or damaged cavity barriers and unrecorded service penetrations - and each of those is a design question for the designer, not a site decision. Rebuilding reinstates the wall as designed, including the continuity of the fire-stopping line and the barriers around every opening, and then windows, balconies, penetrations, rainscreen and weathering are reinstated. The interfaces are where the difficulty lives.

6. 6

   Step 6: Inspect, record and hand over the evidence

   Inspection hold points are set at every stage where something is about to be permanently concealed, and the designer or the fire engineer witnesses them before the wall closes. On a large block that runs to hundreds of witnessed hold points, so the inspection resource is programmed like a trade rather than squeezed in around one. Photographic and written records are taken of every concealed layer, located and indexed so a specific point on a specific elevation can be found again. Installer competence and training records for the systems installed form part of the file. At the end, the whole set - assessment, design, change records, inspection sign-offs, product information, the photographic record and the completion certification - is handed over as the building's information record for the accountable person to hold and maintain.