Concrete walkways in London
The front walk is the first piece of concrete on a London property to fail, and clay is why.
A walkway is a narrow slab. It has an enormous amount of edge relative to its area and very little mass to resist movement, and the older ones were almost always built on a thinner base than the driveway beside them. Clay holds water. Water under a narrow slab freezes and expands every winter, and the walk lifts, tilts and cracks while the driveway, with four times the mass and usually a better base, stays where it was. That is the whole mechanism, and it explains why a homeowner can have a perfectly sound drive next to a walk that looks twenty years older.
The answer is base depth and a real drainage path, and it is worth more per square foot on a walkway than on any other pour. It is also why walkways cost more per square foot than a driveway: forming a three-foot-wide run takes nearly as much edge work as forming something four times the area, and edge work is where the labour goes.
On the heritage streets there is a second question before any of that. A walkway is exterior work, and in a heritage conservation district a new or reconfigured front walk can require a heritage alteration permit. On a century street where the original approach is narrow and part of the streetscape, that is worth confirming before designing something wider.
Where the walk meets the porch, the steps or the driveway apron, each seam gets an isolation joint. On an older house that detail does a second job: it keeps the slab from being locked rigidly to a stone or soft brick foundation that needs to move and dry.
Broom finish gives grip. Exposed aggregate sits well against brick on the older streets and grips just as well, and it hides wear better.
We also pour the steps these walks connect to and the driveways they meet, and cover the rest of our London service area.
East along the 401 the ground and the municipal process change, covered on concrete walkways in Cambridge. Further east the tri-city lots and apron rules differ again, dealt with on concrete walkways in Kitchener.