weed problem with block paved patio

mapuche

Hi.
I have a block paved patio. The blocks are small (cobble block I think you call them). No matter how I try ican't get rid of weeds which keep growing up in the narrow gaps between the blocks. It is very unsightly. I've tried sprays as well as removing the material from between the cracks and replacing with builders sand. I've come to the conclusion that the best way to deal with it is to apply a grout in the gap between the blocks. This gap is quite narrow however and I was thinking of lifting all of he blocks and replacing them with a wider gap between each. Before I do that I was wondering if here is a grout that will work with the existing narrow gap.

Or, is the grout route not the right way at all.

Thanks in advance for any help with ths

foxinsox

Roundup is usually the most effective weedkiller. You may have already tried this?

I know there is a trick of mixing sand and cement then sweeping the powdery mixture into/over the cobbles, when all the grooves/gaps are filled you do a final sweep over to remove as much excess as you can. Then using a watering can with rose on it apply a fine sprinkling of water over it all, hence the cement sets.

I have no idea on the exact mix of sand cement or if this is suitable for cobblelock paving. I would also imagine spraying with weedkiller before applying this would be advisable.

Check it out elsewhere though, this is the interweb, I could be just making all that up!

CJhaughey

Before trying an weedkiller, get some coarse salt (lidl) and sprinkle it on the joints where the weeds are growing.
This will kill them off and stop future growth.
Better and cheaper than weedkiller.
About a Tablespoon per plant will kill them effectively.

Graaaaa

If you decide to take them up to relay them, then check if there's a weed barrier under. Very cheap in hardware stores and will prevent the deep root weeds coming back.
As for joint widths and jointing: very much depends on whether they're clay, concrete, stone, reconstituted stone (concrete really) and what sizes - width, length and depth.
If you let me know I can tell you what mortar or joint sand would most likely be specified.
There will always be some maintenance to keep shallow weeds and mosses out - the better the drainage (slope of the surface in this case) then the less moss.

mapuche

Thanks for the replies everyone. Graaaa, my paving is reconstituted blocks, small rectangular blocks, various sizes. Have silica sand now for the joints. have been advised not to lift and relay but rather wash with a power washer. have tried this but still very difficult to get the dirt out between the gaps. Thinking of lifting to do proper job but very time consuming. also have found a good sealer - AdSeal. More expensive than Thompsons but much better and less expensive than the most expensive (Resiblock). Loathe to use solvent though (have a veg patch nearby). Will prob try washing one more time and them silica. Jointing using sand and cement sounds promising also.