Mowing strip

[Tone0101]

Hello, hopefully I'm posting in the right place but sorry if I'm not.
I've read through this extremely helpful site and have a rough idea of what I'm about to do but my head's well and truly done in so it's time to ask the experts what's what.

I've finally caved in to the the missus and agreed to do a bit of very light landscaping in the back garden which is 10 metres x 8 metres and is at present a full lawn with nothing else in it.

The aim is that there will be the existing square lawn in the middle (which I'll make smaller to accommodate the following....), then moving out from that a mowing strip perimeter square of granite slabs around the lawn and then a perimeter of white spar chippings around the slabs (they will be put on weed block fabric). So, working your way out from the centre of the garden, what we'll have is lawn, then granite slabs, then chippings to the edge of the fence.

I hope you can answer some questions as I'm a reasonably handy DIYer but I'm a bit confused about sub bases etc.

The mowing strip will consist of granite slabs which are
Width: 20cm, Depth: 2cm, Length: 80cm,

What sub base do I need to put under them? Is 5cm or 2 inches of sharp sand enough? I want these slabs to look flush and butted up neatly to each other with minimal gaps and whilst there will be a very minimal foot fall I don't want any movement in the slabs, what would you recommend as a sub base? Do I need to bother about cement etc?

I'm expecting the granite slabs to be a nightmare to cut with an angle grinder - any advice?

I'm thinking about setting out the granite slabs and then taking the ones to be cut to a stonemasons - good idea? or go with an angle grinder (which I'd have to hire) and do it myself?

Thanks a lot for any advice - it really is greatly appreciated.

Cheers.

Tony

[Rich H]

A mowing strip 200mm wide? No point in having a sub-base unless the ground is soft. I'd use a medium strength mortar mix (yes you do need cement), nice and wet to bond to the very dense granite. Usually, digging out turf will leave you with a depth of about 100mm, which means 80mm for the mortar plus 20mm for the slab. 80mm is a bit thick for a bedding course but if you use a wet mix it'll be fine.

At 20mm thick, cutting them won't be a problem with a 12" cut-off saw from a hire shop. Far cheaper than taking them to a mason.

[Tone0101]

Thanks a lot for that Rich, bearing in mid the quantities involved could I get a ready mixed mortar or is it best to mix my own?

[msh paving]

Just mix it yourself, you can go at your own pace then MSH

[Tony McC]

1 - lay the granite pieces on a full mortar bed, as suggested by Rich. You might want to use a bond bridge as described here

2 - some people have had bad experiences laying the silver grey granites on mortars prepared using red or orangey sand. Use silver sand, if you can get it.

3 - some people have had bad experiences laying the silver grey granites on mortars prepared using OPC. Use white cement, if you can get it.

4 - what's going to retain the white spar chippings on the outermost edge?

[Tone0101]

Thanks a lot for the reply 'msh paving'.
I've never prepared mortar or laid blocks before so thanks very much for all your help in educating this very enthusiastis but cautious apprentice.

Tony, in reply to your question:
4 - what's going to retain the white spar chippings on the outermost edge?
The answer is that I'll be digging down a couple of inches so that the white spar will be level with the granite slabs. The garden fence will retain the chippings on 3 sides and some decking will retain it on the fourth side.

Here's a link to the slabs:

http://www.diy.com/diy....ch=true


I reckon you boys in the trade and in the know are probably going to tell me I'm being royally shafted on the price but here goes anyway. I was considering this as a cheaper alternative but the wife wanted the flashier granite.

http://www.diy.com/diy....ch=true

Any tips or advice you have would be more than welcome.
I'll be using 33 of the granite blocks, with ideally silver sand and white cement as per your advice, any idea how much and of what to buy to make the mortar? I'll be using B and Q by the way and will probably keep their Christmas staff booze fund going fo rthe next few years after this 'little' job's done.

I'll keep it simple for this novice and not use a bond bridge - is this OK?

Thanks for taking the time to reply.

Cheers.

Tony

[Tone0101]

I've received some 'advice' from a builders merchant which I seriously question but they've told me that I can make the process far easier. Can I check some questions:

Would I get away with using sharp sand rather than builders sand in the mortar mix?
or
Would I get away with using the sharp sand as a base and sprinkling the cement on top then laying the slabs?

[Tony McC]

Sharp sand for bedding is preferable to building sand, but silver sand is what you really want.

As for the BMs recommendation of sprinkling cement on top of the sand: there's a reason why we keep those f*ckwitts behind a counter. If they had any genuine construction skills, they'd be out on the job with those of us that do. But, as their sum total of knowledge comes from watching Groundforce and Loose Women, we don't allow them out in the fresh air. Pillocks!

[Tone0101]

Cheers Tony, I thought as much. Which just goes to show how invaluable this website and yours and other users help is.

I'm having problems getting the silver sand so I'll probably go with the sharp sand for my mortar bed and the mix will be 4:1.
Unless....another merchant has offered me kiln dried sand, is that silver sand? Can I use kiln dried sand for my mortar?

If that's the case then they are offering exactly the same stuff that I use for the gaps in the block paving. Is that silver sand or does silver sand have something especially different about it from kiln dried sand.

Sorry, I know this must seem like pulling teeth with my lack of knowledge but these are probably the last of my questions!

If I could use this kiln dried sand for my mortar mix 4:1 then I'm there. Is this right ?

Thanks for your patience.

[Tony McC]

KDS might be a sliver sand, but it's not always a silver sand. Stick with the sharp sand and, in almost all cases, you'll be absolutely fine.

[Rich H]

Mixing it is dead easy. Take a decent wheelbarrow, add one bag of sharp to one shovel of white cement (given its cost maybe a spade instead of a shovel). Mix it well then add water, a little at a time, until you've got a mortar which is wet but can 'stand' on its own. Don't get any on the surface of the granite; if you do, sponge it off right away. It'll set like rock and be hard enough the next day to add your chippings.


PS your missus is right, and that's not a bad price for an 800mm granite edging slab.

[Tone0101]

Thanks a lot again for the replies, that's me sorted. I'll get it all ordered and will get cracking - will probably be delivered in about 10 days. I'll let you know how it goes.

[Tone0101]

Job done, and the missus seems happy with it. Took me about 5 days in all to do. I used about one quarter building sand in the mix to add a bit of stickiness to the granite. I know what you mean about the cement burns where you talk about mixing mortar elsewhere on this website - despite wearing gloves, I got a few burns which are on their way to healing.
Thanks again for all your help.

[Tony McC]

So: do we get to see a photie?

[Tone0101]

You could if I could work out how to post one, I click on the image button and it's asking for a URL. How do I add an image?