How can i permanently kill off weeds coming through patio slabs?

Question

after pulling out,jet washing and spraying weedkiller for the last 6 months i still have a problem with weeds coming through the cracks in my patio.

does anyone have any ideas that work in this situation such as homemade solutions or even a good brand of weedkiller that will do the business?

i live in the uk if anyone is recommending a brand to buy.

thanks for any answers in advance

Answer 1

No not permanent I think.   A powerful kill all is sodium chlorate.  Don't get any on plants or beds  . Will kill everything.  But  will need doing again next year    

Answer 2

tractor diesel

Answer 3

You cant, weed killer only lasts for 3 to 6 months, then the little rascals will grow again,boiling water will stop them for awhile, re pointing in tails lots of work and expense,tractor diesel ( as suggested will contaminate the whole area and stink) sorry everybody has the same problem so keep on weeding.