The Brew Cabin

Hi,

With the help of your excellent web site I'm renovating my back yard which is the first time I've really done anything like this. I have a few questions for which I haven't managed to find answers to on the site and would be very appreciative of your advice.

The yard is roughly "L" or perhaps "P" shaped and I intend to lay Indian sandstone flags down the "long arm" and fill most of the rest up with pebbles. Although part of the slab path will be bordered by a wall on either side I'm concerned that the part of the path that abuts the pebbles may slip or creep, over time.

so...

1. Do I need to use an edging or can this be avoided

2. should I use a 10:1 sand:cement mix rather than just sand in the bedding layer.

Initially I was just going to use sand and was going to lay it all in a "oner", then compact it all and then start to lay the flags. I'm assuming that laying the flags may take me a couple of days and so I'll need to add the cement gradually to avoid it going off too early. should I also lay and compact the sand in small doses as I go?

3. Finally (for now) if I put a weed barrier below a layer of sub-base beneath the pebbles will it just get ripped (and therefore becoem useles) when I compac the sub-base? Is there anything I can do to prevent this? I know you're not too keen on these fabrics but the old asphalt in the yard had loads of weeds pushing through it and I'd like to avoid the same fate.

Cheers

Gareth

Hi Dr G,

1 - No - see the adjacent thread about choice of edgings. It covers this very topic.


2 - yes! because the Indian sandstone varies in thickness so much, it's more or less impossible to lay on a pre-screeded bed, and so you have to use individual bedding, and a cement-bound bedding material (the 10:1 mix I keep banging on about) is the best option.
Just mix enough of the bedding to keep you going for an hour or so, and then mix more as and when you need it.

3 - If you have a sub-base AND a cement-bound bedding material, the weed membrane is a complete and utter waste of time. Treat the existing ground (asphalt???) with a good weedkiller before starting work. I prefer Sodium Chlorate, but I have a feeling it's not generally available to the public, so summat like Round-Up or PathClear will have to do. Once the ground has been doused with that, and overlain with cement-bound bedding and the flags themselves, the weeds will not come through - but see the newly uploaded Membrane FAQ for more info.

Good luck!

Thanks Tony for such a quick reply.

I saw your answer to the other edging thread just before I read your answer above so had realised I didn't need an edge. :)

I take it from your reply to my second question that I should be only bedding a small amount at a time so I should follow the sequence

mix sand:cement - lay - compact - lay flag (s)

and then start again when I've got close to the edge of my original bed.

Opps, looks like I didn't explain properly. I wasn't going to use a sub-base beneath the flags (as it's only light use), planning on just putting the bedding mix directly onto compacted soil (I have excavated the old asphalt and soil to ~ 100mm). The sub base is only to go under the pebbles. In light of this is your answer to my question still the same?

Yours

Gareth

When it comes to mixing the bedding, I'd suggest doing a barrowful at a time. Because there's no water added to the bedding mix, you get a reasonable amount of working time - something around 4 hours, so you could knock-up as much as you think you'll need to keep you busty for a couple of hours, rather than mixing just enough to lay one flag at a time.

The membrane - my mistake, I didn't read your post properly. Yes, you could use a membrane beneath the sub-base for the gravelled/pebble-covered area, as that will be prone to weed colonisation. If you level out the sub-grade, compact it and make sure there no sharp stones or bits of glass to puncture the membrane, that will be adequate preparation. These weed membranes are not intended to be 100% weed-proof, but to reduce the opportunities for weeds to get a foothold, so any moinor tears or areas not completely covered are not critical.