Garden Wall Project - help required

[r896neo]

If you use a cheaper flag the secret is to detail it well by adding perhaps a border of setts.

Something like this

http://s3.tstatic.co.uk/images/logos/9875/MayfairFlagsSandstone.jpg

 

[spiidey]

r896neo

Thanks for this - we'll have a look at the suggested flags and come back with any further queries.

 

[spiidey]

Finally time for us to get back out in the gold ol' garden and finish last year's job, hopefully well in advance of the summer.

We need to lay flags/slabs in our "middle" section, behind the retaining wall we've built.

I've attached a diagram below that hopefully shows this. Key points:-



1. The retaining wall is 6 bricks / 600mm high.

2. Behind the retaining wall, there is 200mm wide clean gravel (up to 400mm high / the 4th brick high), with 200mm wide top soil for some plants (behind the top 200mm / 2 bricks).

3. Behind all of that is where we want to lay the flags (dashed pink line).

4. The dashed blue line is the original, sloping, ground level. Note that we did not excavate any earth below the blue line, OTHER THAN (a) the "clean gravel" area, (b) directly below the bottom brick and (c) 150mm either side of the bottom brick.

5. Behind the clean gravel/top soil, we have infilled with some of the clay soil that was excavated on site (green area). Each infill was compacted down at each 50mm depth of soil added.

6. We've levelled the infilled clay soil off to leave at least 200mm from the top of this soil to where we want to lay the flags (yellow area).

7. We are proposing infilling this final 200mm with:- 160-180mm Type 1 (compacted), and 20-40mm wet mix mortar bed (to hold the flags). As I say, the flags would run along the dashed pink line.



Q: Will 160-180mm Type 1 (yellow area) on top of the compacted soil (green area, max 200mm depth of compacted soil), be enough support for our flags, or should we we get rid of all of the infilled soil (green section) and infill that with type 1 instead?



Trying to save us a bit of money by using some of the existing soil we had on site (green area) but don't want to end up in the situation where flags break.

LINK TO ORIGINAL IMAGE:- http://i61.tinypic.com/242sk7c.jpg


Some pics of area that we're referring to in garden:-

 

[spiidey]

Anyone able to help with this - question boils down to whether we:-

1. Leave the infilled soil in the green area and lay the type 1 on top of this

OR

2. Excavate the green area back out and infill the green and yellow areas with Type 1.

 

[spiidey]

Anyone able to help with this - question boils down to whether we:-

1. Leave the infilled soil in the green area and lay the type 1 on top of this

OR

2. Excavate the green area back out and infill the green and yellow areas with Type 1.

Anyone able to help out with this?

 

[r896neo]

you should never put dug out material back in.

Fill it all with type one or type 2. Feel free to throw any rubble you have in first but space it out so as not to create voids amongst it.

you will need a decent weight and quality of plate to compact that depth of fill. A heavy 80kg-ish plate would be best.

 

[spiidey]

you should never put dug out material back in.

Fill it all with type one or type 2. Feel free to throw any rubble you have in first but space it out so as not to create voids amongst it.

you will need a decent weight and quality of plate to compact that depth of fill. A heavy 80kg-ish plate would be best.

Thank you, will fill with type 1.

Was going to give it a go with a good old manual tamper rather than machine. Thoughts?

 

[r896neo]

No. you must use a machine. the heavier the better.

If you were only filling 3 inches a hand tamper might suffice but not for your job.

 

[spiidey]

No. you must use a machine. the heavier the better.

If you were only filling 3 inches a hand tamper might suffice but not for your job.

Why is this the case??

So e.g. filling at depths of 30mm at a time with a hand tamper is no good? If so, why?

 

[r896neo]

You will never achieve the same level of compaction and importantly, even compaction of all areas.

After spending so much time and money skimping the 30 quid for hiring a plate is crazy.

You would need to spend a good day with a hand tamper and you would be broken at the end of it to get the same result of using a 80kg plate for 30 mins.

 

[spiidey]

You will never achieve the same level of compaction and importantly, even compaction of all areas.

After spending so much time and money skimping the 30 quid for hiring a plate is crazy.

You would need to spend a good day with a hand tamper and you would be broken at the end of it to get the same result of using a 80kg plate for 30 mins.

Ok, gotcha, it was just good for my waistline as (you're right) it is tough going with a tamper but was prepared to put in the effort. Tamper was a meaty 8x8 inch cast iron bad boy so was probably doing just about as good a job manually as possible.

Using a machine then, is there any issue using this close to / behind the already built wall? I.e how much of a gap do we need to leave to ensure the vibrations from the machine don't interfere with the structure of the wall (if this is even an issue?)?

We've currently got a 200mm wide clean gravel/top soil section directly back from the wall as shown in the cross section diagram at the top of the page
Is this enough? Wall is the croft wall bricks that arent mortared together.

 

[r896neo]

200mm back from it is plenty As long as you dont actually hit it the vibrations will only serve to lock the clean stone in and make it stronger

 

[spiidey]

200mm back from it is plenty As long as you dont actually hit it the vibrations will only serve to lock the clean stone in and make it stronger

Excellent, thanks.

When using the plate, should we rake in the type 1 in increments of 100mm deep at a time and compact with the plate?

Or can the whole lot up to the 400mm depth be raked in and compacted in one go with the plate?

 

[r896neo]

It depends on the weight and spec of the machine. I would do it in 3'' layers.

 

[spiidey]

It depends on the weight and spec of the machine. I would do it in 3'' layers.

Thanks.

So what exactly should we be specifying when hiring the machine? 80kg weight? What kind of "quality"?

Does the medium version on the link below do the job? Presume we don't need the "hauc" models on these?

http://www.hss.com/g/47428/Vibrating-Plate-Wacker-Plate.html


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Also need a laser level to allow us to measure the level across the site to create the required fall in the sub base for our paving slabs. Had something like this in mind:

http://www.brandontoolhire.co.uk/en/site-works-and-safety/457-multi-directional-laser-level.html

I.e. A self levelling laser level that would rest at one end of the site, with a hand held sensor that we could then take to the other end of the site and ensure we were levelling the points at each of the site with each other, which would then allow us to add in the required height gain to create our fall in the sub base via a builders line.

But £64 for one day hire seems pricey. Is there another similar product we could use that we could either purchase outright for less than £50, or hire for a day/weekend at the £20-30 mark?