Green algae on the york stone flags

[handyman270470]

have my parents house whose backyards always turns green and the walls.

What is the best remedy to cure it permanently, as i always wash it with Karcher jet wash and still appears after few months.

I applied Dulux Fungicidal wash and it still appears back.

Please adivse if there is any solution to stop this green Fungicidal/mould coming back.

How do i add picture on this site please ? or see the below link if this opens.

http://s268.photobucket.com/albums....064.jpg

[msh paving]

Look like the patio has no slope on it so it lays wet all the time,is it possible to relay it with a slope,
as for the stain that dulux stuff comes under the heading of neither use nor orniment...lol

look on this web site
stain stopper
stain stop is the product MSH

[Amogen]

We have some stuff we can put on for you. Its not a permenant resoluton, but is far easier than doing what you doing at the moment.

Let us know if we can be of help.

[Tony McC]

I'd agree with MSH - poor falls are not helping the issue.

The only long term fix other than a lift-and-re-lay would be to have them properly cleaned and then get a quality sealant applied to severely limit the ability of the algae to re-colonise the surface. Even the very best of biocidal washes will have a limited effect over time. A good sealant should give you a least a couple of years.

[handyman270470]

Thank you all for your reply and taking the interest.

It has a fall, but i do not know how the fall has been calculated per metre.

There is a fall straight run i think from the patio door leading to backdoor to the Alleyway.

It is approximatley 10 meter yard length.

These Marshall york stone flags are not smooth surface flags, as it has these corrugated shapes which can hold the water, which is not helping.

I will have to buy the Algex or Outdoor cleaner to remove the Algae.

[Rich H]

It's called a riven surface, although of course they are moulded concrete slabs so it's more accurately a 'riven-effect surface'!

That's not the cause anyway, although it is exascerbating the problem to a certain degree. The main problem as said above is that the paving does not have an adequate fall to drain the water. A slight fall is almost pointless as surface tension will keep enough water on the paving to allow algae to grow. Chemical solutions will only inhibit the problem, and then only temporarily. If you want the problem to go away, re-lay the paving with proper drainage.

[handyman270470]

Thank you for your reply.

Do i need to have the fall one way leading to the alleyway or do i need to do it both way where the Gullys are which i have 3 at the moment on the side building annexe and the new extension.

Which fall do i need to work on is it for every 1 metre a inch fall.

I will measure the party wall from the highest point which is near the french door and the lowest point which leads to the back door leading to the alleyway to see the difference in height, as this will tell me the difference of the height, so i will know exactly the fall.

I have the algae on the brickwork some are mid way of the wall and some are just on the lower part. Algae should not realistically occur on the mid part of the wall, as the water runs down the wall quite quickly and there is less chance of the water to be stagnated.

However you will know well, so any advice will be appreciated.