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Posted: Tue Jul 12, 2016 7:11 pm
by dominoman
I am about to start laying a winding garden path made of square pavers. I've been reading everything on this site and have learned a huge amount. Now time to give it a go!
Could someone check if this plan makes sense?
1. Excavate to depth of paver plus 125 mm (80mm MIN base, 25 MIN laying course)
2. Add hardcore / sub base / MOT type 1 – 60mm. Compact with plate whacker
3. Use Moist mix to do 100mm high for first edge. When dry top up the hardcore
4. Use dry mix to lay pavers. Then compact using a plate whacker
5. Haunch outside edge pavers at the end
I can't decide whether it is better to use bedding of just sharp sand, or to use a Lean Mix of dry sand and cement? If I use sand cement mix I guess it will be stronger, but do I have to compact it quickly after laying it before the cement in the bedding mix starts to go hard?
Thanks a lot for any advice.
Posted: Wed Jul 13, 2016 9:44 am
by Tony McC
Dig depth too shallow
Sub-base way too shallow - read this FAQ
Always lay on flexible bed unless there are *very good* reasons not to do so.
Posted: Wed Jul 13, 2016 7:11 pm
by dominoman
Tony McC wrote:Dig depth too shallow
Sub-base way too shallow - read this FAQ
Always lay on flexible bed unless there are *very good* reasons not to do so.
Many thanks for the reply.
That FAQ article says unbound sub-base needs to be at least 50mm deep, so if I use compacted hardcore then I thought that 80mm (after compaction) would be OK for a garden path?
I think I wrote it badly. I meant to say I do 60mm hardcore, compact it, then lay edge course on that, and then fill in and add another 30mm hardcore, compact it and then add a 25mm bed on top of that.
By flexible bed, you mean a bed of sharp sand, rather than a sand/cement dry mix?
Many thanks for the help.
Posted: Thu Jul 14, 2016 11:25 am
by Tony McC
Where does it say 50mm depth is acceptable? I can't see that and I certainly wouldn't have written that!
The FAQ makes clear that, at the very, very minimum, 75mm compacted thickness *might* be acceptable for very light usage.
Posted: Thu Jul 14, 2016 2:25 pm
by dominoman
Ok. Thanks. I was referring to the first sentence in the FAQ "Generally, a flexible sub-base of unbound material needs to be at least 50mm deep".
I will make sure mine is at least 80mm-100mm after compaction. It's for a garden path so I'm not expecting much weight on it.
When you say "Always lay on flexible bed unless there are *very good* reasons not to do so.", can I ask why that is? I would have just assumed that a sand/cement dry mix bed would be stronger and less prone to insect attack etc.
Posted: Fri Jul 15, 2016 7:16 am
by seanandruby
If you read it all you will see that Tony doesn't recommend that, the recommendation is in the boxes, minimum 75/100 ml. You need to read all the information and absorb, not just one liners :;):
Posted: Fri Jul 15, 2016 9:40 am
by Tony McC
I'm not sure how that reference to 50mm got in there. It must be a typo - whatever: it's gone now!
As Sean says, the minimum depth is given in the table accompanying that piece, and the reasoning behind minimum depths is also given....which makes it even more mysterious how that 50mm reference got there!
Good reasons not to use flexible bed? Where there is no sub-base or a very shallow layer because of, say, tree roots; appallingly bad ground; an area known to be prone to mining/burrowing by invertebrates or small mammals; regular inundation by water.....it goes on.
A bound bed is, by definition, stronger than an unbound layer, but it brings its own problems and cost implications which is why a flexible/unbound bed is preferred over a flexible/unbound sub-base.
Posted: Fri Jul 15, 2016 12:18 pm
by dominoman
Great! Thanks for explaining.
I've taken a week off work to do this path (20 metres long winding path done in Marshall's block paving). Hopefully it will go well. This site is my bible.