Clad over roofs are often sold as an alternative to replacing a conservatory roof. A layer of insulation is added internally by attaching insulation to the ceiling area and possibly also adding boarding externally, that is then fitted with metal sheets to look like tiles. Clad over solutions do not include removing any of the existing structure and do not account for outdated glazing and frames, all to often resulting in a roof that is much too heavy for the structure below.
Drilling into the original structure can encourage condensation so you’ll need to keep an eye out for damp spots. Plus, this type of roof is often not Building Control compliant, or fire safety rated. We recommend you discuss any such plans with a conservatory design company before going ahead.