1. Hello Mike
    Most purchasers undertake a basic home survey which does not look at the condition of the lower, hidden portion of the steel frame.
    The surveyor will enter the loft space and check the condition of the steel roof trusses and also conduct a visual inspection of the exposed upper portion of the frame.
    Often the only indication of lower stanchion corrosion is degradation or “blowing" of the concrete foundation pad at the corner ends of the property. The render (if applies) in this area or indeed along any part of the ground floor exterior walls can be cracked or degraded but this does not automatically mean that the inner stanchions are corroded.
    Significant corrosion of the frames base usually only occurs where water has been allowed to enter through the render as a result of poor maintenance or through poor application of insulation which can allow condensation to build inside the cavity and around the frame.
    Severe corrosion is rare but it does occur.
    Take a look at these earlier posts

    Corroded Stanchions

    Rust Prevention and Maintenance – BISF House.

    The cost for repair can vary considerably depending on the location of the corrosion and the number of stanchions affected.
    Repairs can range from around a thousand pounds up to several thousand but in essence the repair is pretty straightforward and simplistic compared to say a foundation repair of a brick house.