digging out to get 6" beneath DPC

[DIYedboy]

Currently the dpc is about 1" above the outside concrete surrounding my 1908 'villa'. I've dug out to get me the 6" height required, what I'd like to do is spread pea shingle over the clay subsoil, but then I thought, if I do that, during the hot summer, the clay beneath can dry out, shrink n I'm likely to get subsidence. So now I'm thinking I'd better spread concrete all across, that way the ground can't dry out beneath the concrete and I won't have any problems.....................or am I totally wrong and just a big fartypants?

 

[Mikest]

My previous house had a trench filled with pea shingle, for exactly the same reasons as you describe. I had no problems with it at all.

 

[DIYedboy]

I assume after the pea shingle came concrete, which was also 6 inches higher than mine will be, therefore no evaporation.

 

[r896neo]

A pea shingle trench is used in a situation like yours to avoid having to dig out the whole area. Instead you lower the level with a trench maybe 6 inches wide beside the wall and then fill will gravel. This stops any water lying against the house.

Your worries about clay heave and subsidence are totally over the top, it is barely even theoretically possible nevermind practically.

Now write 100 times ' I am a big fartypants'

 

[DIYedboy]

Good man r896, being the fartypants that I am, I've already dug out the 6 inches all the way across. I really don't want to spread concrete over the area, so I'll be buying a jumbo bag of pea shingle then

 

[^woody^]

Also too late now, but you could have just painted some Thompsons (or other clear water repellent) onto the base of the wall 200mm high

 

[janz70]

surely thats not adequate is it ?

 

[^woody^]

What is not adequate?