You are doing a proper job there.
What are the sills, especially the inners like? These rot from inside out, so the outers may seem solid......
and you have had water entering the sill structure
You did repair the jacking points, hopefully the rot was just restricted to the ends.
epcot_pete wrote:then plaster the box sections and inner areas with waxoyl
In my experience Waxoyl is awkward to spray into box sections.
I tried the Bilt Hamber aerosol and found it works well. To improve access to the sills I drilled holes through the steps, these being then
covered by the tread plates.
Ian.