All four options will require some form of secondary framing to support the new cladding and to take this back to the existing steel columns. We expect the existing frame to be in serviceable condition although the cost plan has included for some localised repairs to column base plates once these are exposed.
Where brickwork is adopted at Ground Floor level, some foundation work may be required but this will only become clear once the existing foundations are fully exposed. Our trial pit result would suggest that this is a marginal risk. At this stage we would not recommend new brickwork re-cladding above first floor level to avoid the need for significant foundation strengthening.
It is anticipated that Unit 69 has a limited useful life-span (approximately ten years) due to operational reasons which are outside the scope of this report. The Unit is therefore likely to require replacement within this timeframe irrespective of the findings of this report into the options for over cladding.
The net present cost calculations shown in Appendix I indicate the option to over clad now and replace the Unit in ten years as financially favourable when compared with replacement of the Unit now.
Four over cladding options have been considered by this report. The difference in estimated costs for each of these options is relatively small with Option 2 (over clad with Structherm) the least expensive in terms of initial capital cost. The Structherm system includes on site rendering which is potentially more disruptive to occupants of the existing building during construction, and its medium to long term success is reliant on good site quality control. Should the Unit be retained for more than ten years, maintenance costs will be become an issue.
It is recommended that over cladding is commenced as soon as possible on a phased basis in line with Option 3 (over clad at ground floor level with brickwork and at first floor level with Kingspan Optimo). This should be followed with a planned replacement of Unit 69 after ten years. This option is considered to carry the least risk in the medium to long term despite there being other cladding options with slightly lower initial estimated costs.
©2004 Oxford Method Royalties Management Group