"John" wrote in message
...
Two questions really: Our semi (c.1962) has a concrete slab outside the
front door, approx 2m by 1.5m. I feel I ought to replace it ...

(1) Not only is it very grotty by now, but it has sunk by about 3.5cm,
away from under the front step. (If you see what I mean: the front step
is of course a big concrete block which presumably is built into the
walls; you step down on to the concrete slab; the slab was originally
laid flush up to, and under the front edge of, the step; there's now a
3.5cm gap between the top of te lsab and the bottom of the step.)
Question: should I be worried that the slab has sunk by such a depth
over the years?

(2) Question: If I just break up the slab in situ, and possibly remove
an inch or two of the rubble, can I save on new concrete by just using
it as (rather deep) hardcore?

Cheers - (and thanks for all the inestimable advice gleaned by us
lurkers!)
John

Hi John,

Seen this before many, many times, and the only answer is to take the lot
away and build up the ground below it ready for a new pour of concrete.

What happens when you add to the surface of it is, you're also adding more
weight to it, and so you make it sink faster. If you take the whole thing
away and treat the ground underneath with a new bonding of modern fibre
webbing and build it back to where it should be. Then shutter it off to
size and pour a new base, then it will last a whole lot longer. The one
that's there has lasted since 1962, so you can expect the new one, if done
right, to last just as long. How do the old timers say it ? "Will see my
boots off" :-))


---
BigWallop

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