The Brew Cabin

Posted: **Wed Apr 07, 2010 10:15 am**

I'm laying about 55 square metres of indian sandstone (30-40mm thick) in the garden. I've read lots and lots of the site, but I'm not sure I've understood it properly. It seems to suggest a bonded base of about 9 grit sand to 1 cement, no gravel (sounds fine), but only 35-50mm of it, directly onto the soil (I was expecting to have some other sub-base underneath). Have I read that correctly, and do I just need to run a compacter over the soil first?

Thanks

Posted: **Wed Apr 07, 2010 6:39 pm**

do you know del-boy and dave?

you really should have some subbase,trig
i know its hard work digging it out but such is life in the paving game
for pedestrian only dig out any topsoil,and lay 100MM of type to your falls then compact
then start laying flags/slabs
LLL

Posted: **Wed Apr 07, 2010 8:18 pm**

Thank you for the reply. I would like to do it properly, whatever method that is. I'm trying to get my info from the Laying Paving and FLags page. The individual bedding method seems appropriate for my choice of stone, and under the Construction heading it says:
"There are only two essential layers to light-use flagged paths and patios: the flags themselves and the bedding. For pavements experiencing heavier usage, or where the ground (sub-grade) is unreliable, a sub-base may be used. Drives, forecourts and public footpaths should use the thicker type of flags (50/63/70/80mm) or may use a concrete sub-base onto which the flagstones are laid directly before it sets."
Given that my usage will not be heavy, that means no sub-base is required?

Under the Sub-grade heading it says:
"The surface needs to be dug off to a depth of approx. 90mm, assuming no sub-base is required. The depth of dig can be calculated as...
(average depth of flagstones + 35-50mm bed + any sub-base required)"
which would sound fine, except that it's suggesting I don't need a sub-base?

Again under the heading Sub-base it says
"This will not normally be required for a path or patio unless there is concern regarding the suitability of the sub-grade."

So are these instructions not right?

Many thanks

Posted: **Wed Apr 07, 2010 8:30 pm**

depends on your subgrade, the lightly-hood your subgrade is not solid enough

Posted: **Wed Apr 07, 2010 8:40 pm**

i`m not a pro mate but if you dig down 100-150mm below your patio and fill with type one, hire a whacker plate (medium heavy) and compact thoroughly the subase will never move.

all of this information and more is on the main site, grab a beer and spend another few hours reading.

Posted: **Wed Apr 07, 2010 8:40 pm**

technically you don't need a subase, if the subsoil is sound. As we don't know if you subsoil is sound, we 'err on the side of caution and advise you put a subbase in.. Only you know the answer :;):

Posted: **Wed Apr 07, 2010 8:43 pm**

No my subgrade is nothing special. I was just following the instructions on this site which seem to suggest you don't need more than sand and dust. Anyway, ignoring that...

how would you suggest I construct it all (in basic, as I'm just a DIYer).
EDIT
Just seen the other replies, thanks

all of this information and more is on the main site, grab a beer and spend another few hours reading.

I've seriously read loads form this site. There is loads of useful information, I've learnt about picture framing and spot bedding and plenty more, but I'm sure some of what I've read has spilled out, and as I've quoted above, the 9 grit sand: 1 cement under indian sandstone is what the site recommends.

technically you don't need a subase, if the subsoil is sound. As we don't know if you subsoil is sound, we 'err on the side of caution and advise you put a subbase in.. Only you know the answer

The sub-base isn't great, so shall I go for:
soil
sub-grade - compacted MOT or something? - how many mm?
bedding later, 30mm ish of 9:1 grit sand:cement

Posted: **Wed Apr 07, 2010 9:12 pm**

Yes it does show on the site that there is no need for a sub base and a mix of 10:1 sand/cement as bedding. I can see your confusion but it is advice for a diyer etc.
But when you ask a question in the forum the advice you receive will be from contractors etc, and they will recommend a sub base of 100mm of type 1 stone which will be compacted. Then a bedding mix of 6:1 or 5:1 and so on.

Posted: **Wed Apr 07, 2010 9:14 pm**

have you no chalk where you are?
chalk is a great subbase
failing that 100mm type1 wacked,25-40 mm bedding of 6:1 wettish mix,then your slabs
it will last a lifetime
bedding onto mud is pure cowboy stuff, and Will fail in quick time in most locations
regards LLL

Posted: **Wed Apr 07, 2010 9:51 pm**

Thank you all for your help, I really appreciate it.

Yes it does show on the site that there is no need for a sub base and a mix of 10:1 sand/cement as bedding. I can see your confusion but it is advice for a diyer etc. But when you ask a question in the forum the advice you receive will be from contractors etc, and they will recommend a sub base of 100mm of type 1 stone which will be compacted. Then a bedding mix of 6:1 or 5:1 and so on.

Well I sure am confused. If bedding onto mud is pure cowboy stuff, why is it recommended on the site (because the site doesn't say 'only if you have a good sub-base').

I appreciate that a lot of posters here are contractors, but we all have to do it properly - the only difference is the intended use, whether it's public, vehicle or light pedestrian.

have you no chalk where you are?
chalk is a great subbase

My sub-base is mostly light soil, so I will follow the recommendations here.

failing that 100mm type1 wacked

I have a lot of hardcore left over that I will have to skip - if I break that up nicely can I mix it with type1? And is mot type1?

25-40 mm bedding of 6:1 wettish mix,then your slabs

Reading the site about dry, moist and wet mixes, I'd prefer not to use a wet mix for a couple of reasons: I don't want water containing cement to soak into the slabs, and I don't want to accidentally stain the slabs. I'd also like laid slabs to stay put while I'm tapping the next slab down.

Posted: **Wed Apr 07, 2010 11:11 pm**

as long as the hardcore is 35mm and smaller you will be ok
when i say wettish I dont mean sopping wet
i mean wet enough so that it will hold its shape a little bit if you tipped a bucket upside down
too dry can lead to rockers IME especially for DIYers

also i have never encountered the staining from too much cement,maybe i have just been lucky
cheers LLL

Posted: **Thu Apr 08, 2010 12:25 am**

excellent, thanks

Posted: **Sat Apr 10, 2010 8:05 pm**

I've popped a photo of the dig for the brick path in the block paving sections, so to be fair to the flags, here's where they are going:

Garden Design - large 2 rectangles are grass, path is obvious, patio at the top (there's a guest house there) is fairly obvious too, but the patio at the bottom (by the main house) isn't too clear... the rectangle to the left is an existing pergola and the patio will go under that and to the main house that just comes into view at the bottom:

This pic shows where the patio will go by the main house and pergola:

And this pic shows the area for the patio outside the guest house:

Finally, here's the dig for the path that links the two patios:

The path is mostly dug, as is the patio by the guest house, and I won't start on the patio by the house until the others have made a lot more progress. Any comments/suggestions welcome

Posted: **Thu Apr 15, 2010 6:05 pm**

I've got most of the mot compacted (wow, didn't expect to use so much, more arriving tomorrow). I was then going to lay the slabs on 30mm ish of 6:1 sharp sand to cement, but on reading through the website I'm now confused and am wondering if I'd be better off with some soft building sand?

Is it all just personal preference, or is there a reason to use one option over the others?

Thanks

It's 100mm of mot:

Posted: **Thu Apr 15, 2010 8:24 pm**

i lay on 40-50mm 5-1 sharp sand/cement wettish mix, i would post some photos of a job were on at the moment of some indian sandstone we have laid that im especially proud of but my internet is cack....maybe another time.

Building sand is for building with, sharp sand is the stuff you want

Subbase looks good and i must say i realy like the brick path you have laid, wouldnt mind doing one like that myself!

The Brew Cabin

What base for a new patio?