I've got an old crazy paving patio, which while still structurally good,
look its age, so Im planning on facing it with blocks.
My plan is (after pressure washing) to cement the outside rows in with a
mix of 3 sand to 1 cement to form a strong outside frame.
For the middle Im planning on putting 2cm of sand or sand / cement mix
to lay the blocks on top of.
The current patio is at a slight angle to keep water away from the house
which is good and I intend to keep that angle.
Im worried that any water will eventually liquefy the sand. so I
thought about either putting a number of holes in the 2cm layer of
cement on the lower level to let the water out, but then the sand will
also leave, making the blocks uneven over time. The other options I
thought of were
1. Break the cement in-between the crazy paving to allow water to leak
though, although I suspect there will be some movement, but not as much
as before.
2. Use a dry bonded mix of 10 sand to 1 cement mix to hold the main area
of the blocks in place. The water will simply run off and water my lawn.

Either way given the thickness I was wondering if tamping the sand down
with a vibrating plate was required with such a little depth.

Any views or other options?



---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On Wednesday, 17 February 2016 06:36:39 UTC, AndrewW wrote:
I've got an old crazy paving patio, which while still structurally good,
look its age, so I'm planning on facing it with blocks.
My plan is (after pressure washing) to cement the outside rows in with a
mix of 3 sand to 1 cement to form a strong outside frame.
For the middle I'm planning on putting 2cm of sand or sand / cement mix
to lay the blocks on top of.
The current patio is at a slight angle to keep water away from the house
which is good and I intend to keep that angle.
I'm worried that any water will eventually liquefy the sand. so I
thought about either putting a number of holes in the 2cm layer of
cement on the lower level to let the water out, but then the sand will
also leave, making the blocks uneven over time. The other options I
thought of were
1. Break the cement in-between the crazy paving to allow water to leak
though, although I suspect there will be some movement, but not as much
as before.
2. Use a dry bonded mix of 10 sand to 1 cement mix to hold the main area
of the blocks in place. The water will simply run off and water my lawn.

Either way given the thickness I was wondering if tamping the sand down
with a vibrating plate was required with such a little depth.

Any views or other options?



---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

You must use "sharp" (coarse) sand.
If you use fine sand, it comes up the cracks when wet and walked/driven on & you get low spots/puddles.
Laying these blocks is not as easy as it looks.
If you don't compact the sand you get low points/puddles after a while.
The main snag is the weeds you get with so many cracks.
And they look **** with algae if you don't pressure wash regularly.
Especially light colours.

AndrewW wrote:
I've got an old crazy paving patio, which while still structurally
good, look its age, so I'm planning on facing it with blocks.
My plan is (after pressure washing) to cement the outside rows in
with a mix of 3 sand to 1 cement to form a strong outside frame.
For the middle I'm planning on putting 2cm of sand or sand / cement
mix to lay the blocks on top of.
The current patio is at a slight angle to keep water away from the
house which is good and I intend to keep that angle.
I'm worried that any water will eventually liquefy the sand. so I
thought about either putting a number of holes in the 2cm layer of
cement on the lower level to let the water out, but then the sand will
also leave, making the blocks uneven over time. The other options I
thought of were
1. Break the cement in-between the crazy paving to allow water to leak
though, although I suspect there will be some movement, but not as
much as before.
2. Use a dry bonded mix of 10 sand to 1 cement mix to hold the main
area of the blocks in place. The water will simply run off and water
my lawn.
Either way given the thickness I was wondering if tamping the sand
down with a vibrating plate was required with such a little depth.

Any views or other options?

You might be better off using slabs rather than blocks laid over the crazy
paving.

Blocks allow a lot of water through and really require a porous bed, either
sand over stone or sand over compacted soil if it's just for foot traffic.
You won't get them anything like level using 20mm of sand or mortar and that
will wash away pdq, my advice (if you really want to use blocks) is to
remove the crazy paving and put 50mm of sand in it's place and lay the new
blocks on this