Patio cleaning

[Android 07]

Good evening.

The slabs in my patio were laid incorrectly by the builder. The idiot did not lay weed control fabric underneath. So, weeds grow in abundance from between the slabs.

I have pressure washed away the weeds today.
What should the next step? Brush in kiln dried sand in between and then brush in dry mortar and then sprinkle/spray water on top?
I am rying to prevent the weeds from growing again.

 

[Cheslea2010]

The weeds won't be growing up from underneath they are caused by seeds landing in the joints and germinating. Dry mortar will crumble and wash out next time the patio is cleaned. I would opt for a strong wet mix and apply with a pointing gun. Should stop the weeds. There are also various jointing compounds in different colours which give a firm finish but at greater cost.

 

[Android 07]

The weeds won't be growing up from underneath they are caused by seeds landing in the joints and germinating. Dry mortar will crumble and wash out next time the patio is cleaned. I would opt for a strong wet mix and apply with a pointing gun. Should stop the weeds. There are also various jointing compounds in different colours which give a firm finish but at greater cost.

It is a bit of a pain going round the patio kneeling down and applying wet mix. I was hoping to be clever

 

[Cheslea2010]

It is a bit of a pain going round the patio kneeling down and applying wet mix. I was hoping to be clever

I know what you are saying, but you will be re-doing it every year if you just brush in

 

[Android 07]

I know what you are saying, but you will be re-doing it every year if you just brush in

Forgive me but I tried wet mixing and gave up after half an hour. It is way too much work. I have gone down the route of dry mix and then hosing it to make wet.

I have bricks on my driveway and an abundance of weeds growing from in between them. What is the sealing solution here? Pressure wash > Kiln dried sand > Seal with mortar?

 

[Cheslea2010]

Forgive me but I tried wet mixing and gave up after half an hour. It is way too much work. I have gone down the route of dry mix and then hosing it to make wet.

I have bricks on my driveway and an abundance of weeds growing from in between them. What is the sealing solution here? Pressure wash > Kiln dried sand > Seal with mortar?

By 'bricks' do you mean Block Paving? If so, traditionally Kiln Dried Sand was used but it is now preferred to use a 1-4mm Joint Aggregate as it is more free draning and tends to stay in place bettter than sand. A bi-annual dose of glyphoshate weedkiller should keep the weeds at bay.

 

[Android 07]

By 'bricks' do you mean Block Paving? If so, traditionally Kiln Dried Sand was used but it is now preferred to use a 1-4mm Joint Aggregate as it is more free draning and tends to stay in place bettter than sand. A bi-annual dose of glyphoshate weedkiller should keep the weeds at bay.

Yes, I meant to say block paving. Will aggregate brush in between? The builder I used did not lay weed control fabric underneath!

By the way, I have to redo my dry mortar mix in my garden. The mix did not solidify at all even after hosing. I have a feeling that the Blue circle cement is at fault as it is a year old and has been sitting in the shed.

 

[Munroast]

the seeds just grow in the sand, a membrane underneath wouldn't help.

I use roundup about every 6-8 weeks through the summer, and power wash it and resand (kiln dried really fine stuff) maybe every 3 or 4 years

I once dried my own sand off the beech and brushed that in, I think the salt content helped keep the weeds at bay, for maybe a year very very little tried to grow, of course by the following year all the salt would be washed out with rain, and the weeds just came back.

 

[bob_fossil]

The builder I used did not lay weed control fabric underneath!

I've been doing groundworks since the 80s with the original old Marshalls 63mm blocks and using a non-woven geotextile under everything since the late 90s buying PolyFelt in 450m rolls. It absolutely does help both preventing ingress from the sub-grade into the sub-base and at a macro level helps slightly disperse a load over a greater area; has to be the right stuff though- no point using that cheap "garden fabric" stuff they sell in DIY shops, yet I've seen people using it... even directly under the blocks, on top of the screed, lol.

Weeds growing in block joints is not always a membrane issue. If the installer threw the blocks down on a dusting of sand and cheap garden geotextile then it's going to sink, pump, pond and have all kinds of junk growing through in no time. If it's on 4" of MOT and 2" of grit or granno, it'd take longer, but stuff would eventually get through.

Often it's a maintenance issue - owner or "professional" contract cleaner. Power washing blocks, firing out all the good stuff, depositing all kinds of junk deep into the joints and topping up with sand just provides perfect growing conditions for a better crop of weeds later in the year or the following Spring... not to mention ruining the paving surface by removing all the fines, exposing the aggregate and giving moss plenty more anchor points to have the paving look untidy.

This is how I clean my own paving: Sodium Hypochlorite 14%/15% (strong bleach, sold as swimming pool chlorinator), dilute with water 2:1 or 3:1, give it a jiggle with a stiff brush on any particularly bad areas, then hose it away 30 minutes later. No harm done to the paving, looks new. Top up any missing sand when dry. I'm not suggesting anyone else do this, not my advice, it's just what I do to my own driveway (Tobermore Tegulas, so massive joints in the corners, very little between paviours as no lugs).

Once you take a pressure washer to block paving, even if it's got a fancy directional surface cleaning attachment you paid extra for along with assurances it did far less harm, then you're forever chasing it and it'll only get worse.

 

[JohnD]

Pathclear

A weedkiller which leaves a film preventing the germination of seeds.

Do all your scraping, pulling and filling before you apply it, because disturbing the surface breaks the film, allowing weeds to grow.