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Hi, Got a mega problem here i hope you may be able to help.. had a patio laid with indian sandstone flags..50m. The builder used the dob and dab method of laying, hence leaving large voids in the underside of the ground he was laying on. When it came to grouting.. the voids underneath never seemed to fill, he used sand&cement..it collasped..then just cement, sweeping the entire area, and leaving it..the damage to the stone is awful(he's nowhere to be found needless to say) have used stone cleaning solutions, power washed it also.. most of the grouting and collasped, weeds growing thru. Have managed to clean alot of cement off, but have cement around the edges of most of the flags, have tried to softly wire brush clean, but still looks terrible, and its too costly to replace. Is there anything more i can do? Would appreciate some expert help as i'm all out of ideas here

See our project on cleaning drives and patios. You can try power washing and acid.

Many thanks for your reply... I have already used both methods you have suggested, even the acid didnt work...

Hi Amanada,

I really feel for your problem. It drives me mad when i hear of these sloppy builders who bring such a bad name upon the landscaping industry. As you are now aware, "dot and dab" is not the way to ever lay paving. Until recently, I believe Marshalls showed this as a method in their brochure for laying paving. However they have recently seen the light and changed. Another down side to laying stone like this is that you will have visible witness marks where the stone touches the mortar underneath, since the areas in contact with the mortar remain damp, and the air gaps dry out, giving a very visible "staining". However this seems to be the least of your problems. As a professional paver, I can see little remedy for your situation other than the obvious - renewal. I assume you have tried a standard mortar removing agent from any of the DIY stores to no avail. I am very sorry to hear of your predicament. Hopefully you can find a satisfactory solution, or a good lawyer!!

hi Amanda ,re:indian flagstones,your solution to cleaning may be to have them sandblasted, when done they look wonderful.Grinch

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