Laying Paving Slabs In Garden

[Dave1UK]

Hi,

We have garden paving slabs (430mm x 430mm) in about 6m sq section. There are always weeds growing out of the gaps, have plucked them out several times and also several slabs are slightly uneven with a few cracked.

Slabs can be lifted off quite easily as they are just laid on sand. I am aware this isn't the right/best way to do it but this is a rental property so not responsible for whoever done it this way (whether previous tenant/landlord).

I am going ahead and removing all the slabs and thereby removing any weeds/roots present underneath. I will also be putting the cracked slabs onto the back sections for now - will potentially replace if I find a good deal on second hand marketplace/elsewhere.

I am wondering however how I can make the best of this? The ground is basically already level although some slabs were uneven. I don't want to uproot the whole garden and redo it as it should be done as it would frankly be quite costly and time consuming.

I was wondering whether there would be any benefit to laying mortar (mix of 3/4 sharp sand to 1 cement) on top of the compacted sand and levelling the slabs off that way? I can remove about 1+inches of the top so it levels off well. Or would this be just as bad as just putting the slabs back on as they are?

Thanks.

 

[berty3000]

Looks identical to what I had up until two weeks ago. Those concrete block things retaining a load of sandy muck stuff with old concrete flags on top. All gone now, I'm happy to say.

Indian sandstone flags are the cheapest hard surface option and can he found for decent prices online (like Inifinite Paving) who I ordered mine from. It has absolutely transformed the back garden. Really beautiful stuff. I did have to put hardcore down and then coarse sand mortar... anyway, just thought I'd mention that...

If you're really on a budget... if that sand and soil crap is stable and well compacted, possibly has hardcore under it as well, then you can do the mortar option you've suggested then relay your old concrete flags. You'll then want to point up the joints. A decent jointing compound is worth investing in so it doesn't all break out as soon as you use a jet wash to clean it all up.

Just a tip on weeds... they're not coming from underneath. They result from seeds dropped in very primitive "soils" that have accumulated in the surface joints and cracks, basically dust, dirt and other bits. You cannot escape this. You have to pull them up every year, several times probably over a summer. The longer you leave it, the more likely the roots will go deeper and underneath stones, and then be harder to remove. This is one of the reasons people with block paving are always moaning about weeds. Their surface has hundreds and hundreds of joints for stuff to accumulate in, seeds end up spouting, and they then leave the weeds to grow and the roots get under the bricks.

 

[Murdochcat]

If it’s a rental property shouldn’t you be getting the landlord involved?

 

[Dave1UK]

Looks identical to what I had up until two weeks ago. Those concrete block things retaining a load of sandy muck stuff with old concrete flags on top. All gone now, I'm happy to say.

Indian sandstone flags are the cheapest hard surface option and can he found for decent prices online (like Inifinite Paving) who I ordered mine from. It has absolutely transformed the back garden. Really beautiful stuff. I did have to put hardcore down and then coarse sand mortar... anyway, just thought I'd mention that...

If you're really on a budget... if that sand and soil crap is stable and well compacted, possibly has hardcore under it as well, then you can do the mortar option you've suggested then relay your old concrete flags. You'll then want to point up the joints. A decent jointing compound is worth investing in so it doesn't all break out as soon as you use a jet wash to clean it all up.

Just a tip on weeds... they're not coming from underneath. They result from seeds dropped in very primitive "soils" that have accumulated in the surface joints and cracks, basically dust, dirt and other bits. You cannot escape this. You have to pull them up every year, several times probably over a summer. The longer you leave it, the more likely the roots will go deeper and underneath stones, and then be harder to remove. This is one of the reasons people with block paving are always moaning about weeds. Their surface has hundreds and hundreds of joints for stuff to accumulate in, seeds end up spouting, and they then leave the weeds to grow and the roots get under the bricks.

Yeah the sand/soil seems to be well compacted. If you see that huge root in the photo that spanned along about 8 slabs assuming that's why nearly all were basically cracked in that section.

The slabs had/have no pointing at all just basically soil in there...will be doing the pointing either way.

If it’s a rental property shouldn’t you be getting the landlord involved?

Landlord is fine with these sort of works/'improvements' always inform them of anything. This is just a DIY/improvement I want to go ahead with as see ourselves staying here for few more years. Will be out of my pocket as it isn't really a necessity but just something I wish to have done, don't mind as not a huge investment.

 

[DiyNutJob]

This is one of the reasons people with block paving are always moaning about weeds.

If you kill one weed, a different weed species will grow. Roots are not relevant, I don't think. I don't pull them up, I just string trimmer what is on the surface. Chemicals are no use either. Rain washes them down the soil leaving good soil on top. Biology is resilient. You'll just have to keep fighting them for space.

 

[cdbe]

As you say, clean off the organic material, level and re-lay on 5 dabs of 6:1 sharp/cement. Not the most professional method but will be fine for a good few years, point with a slightly stronger mix 4 or 5:1.

 

[Dave1UK]

If you kill one weed, a different weed species will grow. Roots are not relevant, I don't think. I don't pull them up, I just string trimmer what is on the surface. Chemicals are no use either. Rain washes them down the soil leaving good soil on top. Biology is resilient. You'll just have to keep fighting them for space.

Yeah although as I have the tiles up may as well kill whatever I can before placing them back. Can also see there are actually a lot of dead roots, assuming the survivors were due to no pointing having been done or that it just broke down and was left unfixed who knows.

As you say, clean off the organic material, level and re-lay on 5 dabs of 6:1 sharp/cement. Not the most professional method but will be fine for a good few years, point with a slightly stronger mix 4 or 5:1.

Appreciated, few different ratios being thrown about online.

Any advice on doing this during the heatwave in the shade, should the mixture be "wetter" so it doesn't set as quick/crack or keep watering it slightly after being done?

 

[cdbe]

Any advice on doing this during the heatwave

I would wait till next week, or mix in small batches and give the back of the slabs a good wetting. I'm doing 30 m² of porcelain tiles and the heat's killing me - but better than trying to do it in the rain.

 

[23vc]

I’d also slurry the back of them before laying with at least a cement and water paste, in my experience less likely to pop that way

 

[Dave1UK]

I’d also slurry the back of them before laying with at least a cement and water paste, in my experience less likely to pop that way

Yeah I ordered some SBR bond for the tiles to stick to the cement. If anything may be of a little more help.