Laying in the rain; drain cuts

[markocosic]

Hi,


DIYer here laying ~36m^2 of boggo Marshalls block paving in Cambridge (mostly) using Tony's excellent advice. (except when it comes to carrying on regardless of it pushing it down)


Background first then two questions!


Background:

Postcode is CB4. The first 4 feet are clay. Proper sticky compacted clay that's liquid in winter (like walking on the the dried surface of cold porridge and you can sink bricks into it with your feet) and concrete in summer (when doing the fenceposts I used an Aldi kango hammer for the first foot)

After 4-5 feet you hit a sand/gravel layer that drains ok. Kid brother also lives in CB4 and block paved his 50 m^2 (courtyard) back garden by dropping a 1 m^3 soakaway in the middle sat on the sand/gravel layer then paving over the top of it and this works fine. I've copied this with an overflow to the drains so I'm happy that once at finished level it should drain ok.

Unfortunately the heavens opened in October, it hasn't really stopped since (we usually get ~50 mm/month but it's been >100 mm/month for the pas 5 months), and I didn't get to finished levels before it started.


Specifically:

- Excavated 250 mm of compacted clay (previously there were PCC flags "laid" directly onto the soil and these sank relatively evenly...until the water board can along and dug a 2 m^3 hole in the front garden to fit a meter)

- Terram T1000 textile (if you don't put this the rocks just sink into the clay porridge and the fines come to the surface in winter)

- 18 tonnes of crusher run compacted to refusal in 75 mm layers; nominally 150 mm thick compacted but where it sank (I hired a Wacker DPU3050He from Speedy and knocked seven bells out of it) it might be nearer 230 mm

- Soldier course laid on 100 mm of concrete against pavement to the front is the front edge edge. Solider course laid on 100 m of concrete against concrete fenceposts with concrete gravel boards is one side (public footpath). Solider course laid on 100 mm of concrete against wooden fenceposts / haunching is the other side (neighbour). Line drain set in 150 mm of concrete plus a solider course sat on ~30 mm of concrete on top of the 150line drain concrete is the back edge.

- 1:60 fall in both directions; line drain along the back edge nearest the house; to a gooey bit of garden to get some shrubs etc later.


Question coming...

I was ready to screed, started spreading the sharp/grit sand, then the day job got busy, the heavens opened, and the whole bloody lot is very, very, wet.

The crusher run was "40 mm to dust" concrete, bricks, and mortar. I've wacked the living daylights out of it and that wacker was more than capable of turning any protruding brick into more dust or bashing any protruding lump of concrete into the surrounding bricks/mortar until they became dust.

It's stable (and was a bugger to scrape down any high spots) but isn't exactly free draining. I've now compounded the issue by (1) adding the line drain/edge courses that prevent runoff into the garden and (2) starting to spread the sand (had to move it because of where it had been dropped, and had the bad idea of putting it into its final position)

So now I have a bowl with some sharp sand soup in it. Put a couple of blocks on this and whack them with a hammer and lump of wood and it settles very easily with water oozing out of the joints. Shovel it into a bucket and "drop" the bucket on the ground a few times and it settles down with the top surface just water.

Where I'd like to start the paving (downhill edge nearer the line drain) is wetter than where I'd like to finish.


Question...

What should I do next given that I've done an oopsie?

- spread it, wait a bit, lay anyway
- pile it up in a big heap, wait a bit, then shovel from the top and try to lay in sections
- other?


Second question is easier!

There's a water meter in the driveway. I'd like to set the cover and an edge course around it in concrete so that if it sinks (hopefully it shouldn't - I excavated a deep cone around the water meter and backfilled first with weak concrete mix then with some layers of crush before the texitle went down) the whole assembly sinks evenly.

What patten do you suggest around this drain cover? My edge elsewhere course is solider course. All the blocks are charcoal colour. (SWMBO hates brindle and charcoal or brindle were the only ones on offer at Travis Perkins...)


Photos:

Original


It's all clay up top and wet


View towards road you can see tight surface and wetter its towards the house/drain edge. The far end wasn't wacked at the time because the sand got delivered onto it whilst I was out


High spots scraped down again ready for me to make the mistake with sand and whack the last bit. Note water meter surround poking up:


Dunno what pattern to use around this drain. The other 4 edges are simple solider course:



Also this is super easy to use for what it's worth:
https://imgbb.com

[markocosic]

Another question:

Which plate would you use for the sand and blocks rather than the sub base?

https://www.speedyservices.com/plate-compactors-hire

Would the electric (12 kN) jobbie do the trick? (thinking of noise/neighbours given I'd be doing this outside working hours)

[Tony McC]

Question...

What should I do next given that I've done an oopsie?

- spread it, wait a bit, lay anyway
- pile it up in a big heap, wait a bit, then shovel from the top and try to lay in sections
- other?


Second question is easier!


What patten do you suggest around this drain cover?

You need to let the sand drain before you attempt to lay. The key assessment we use is to squeeze a handful of the sand and see what happens. If water oozes out, it's too wet; if dry sand trickles out between your fingers, it's too dry.

It should clump together loosely, with no excess moisture.

Piling it up will helkp the upper section drain out, but the base will still take a while. Spreading it out will also work but it all depends on that sub-base you have. Cruched 'hardcore' is never as free-draining as a crushed primary aggregate, so it may take a few days of dry weather before trhe sand is usable.


As for the gully detail, I'd use either a 100mm or 200mm wide soldier around the fitting. You could consider using Mitred Corners for a more professional finish but it's not critical.

Here's a few examples.....

[Tony McC]

Another question:

Which plate would you use for the sand and blocks rather than the sub base?

https://www.speedyservices.com/plate-compactors-hire

Would the electric (12 kN) jobbie do the trick? (thinking of noise/neighbours given I'd be doing this outside working hours)

The little farty lecky thing would be OK for blocks and jointing but it's neither use nor ornament for sub-base compaction.

[markocosic]

Thanks Tony,

Once you see those part blocks inboard rather than outboard the mitres make complete sense. Couldn't see that looking at the drain and the whole blocks to save my life though! #1 looks nicest to my eye and is as easy to cut as #2 with diamond disk in 4.5" grinder. (chop top and bottom then tap with lump hammer)

On the sand...

https://youtu.be/ocHrr3FcFOU

Dry enough?

[Tony McC]

Ooooooh.....very borderline. Probably just about OK but I'd prefer to see it slightly fluffier

[markocosic]

Update, thoughts, and stuff learned for what it's worth:


I gave up waiting for the sand, bought myself a 36" rake, thoroughly mixed the stuff so that it was evenly damp, and cracked on with this very borderline sand. In hindsight I think this was a good move as it's not stopped raining since and it would never have got done otherwise. I won't pretend the following is strictly in accordance with Tony's age advice (thanks) but I think it'll do.


Rain was such that once the edging course was laid I had to hammer drill through my sub base to drain it...




Then I left "the last bit" of exceedingly we sand at the bottom of the drive to dry out whilst screeding and carefully laid to a line:





Here's why you mix blocks form packs. She and I quite liked the effect but sadly they've all dried out evenly now:




Drain ended up looking like this:



Which drew attention to it. So I removed the blocks and did this:




I hated that less and figured that it was less likely to move than laying up to a border as one block width immediately around that drain are laid on the flat-topped concrete haunching of the drain using a thin (~5mm) layer of 3:1 dry mix. They didn't break when I wacker-ed the drive so it must have been enough to stop them rattling against the concrete. ]


It was dry enough at the end fo Jan to screed and lay the last bit afterwards. Avoid wacker-ing within a metre of the unbound edge and they didn't move. Then screen, lay up to the line drain, and beat the daylights out of it.


Wacker-ing on moist sand is fun. It liquifies and goes to full compaction pretty much instantly and follows the line of your sub-base... Bash away at the blocks some more and the finer bits of the screeding sand start rising with the water between the blocks, then you crack a few. I beat the living daylights out if it (breaking ~ 30 blocks) and when removed (an ordeal) the sand had actually risen halfway up the gaps between the blocks. Upside down jointing...

[markocosic]

Final result:



For those wondering what's under the tarp...the John 'F' Prescott...another unfinished project...



I'm happy enough with that...but don't fancy doing it again so chucked a tip in the jar instead of buying the book.


One technique that did work well was levelling by night. If doing a dead level lawn pop your laser at "one rake height" above the finished mud level and keep raking until the top of the laser just kisses the rake:



Same thing for block paving. Set some TAUT strings up. Rake your sub-base with the string between the tangs of the rake until the string touches the underside. Wacker it. Then "rake off" any excess with the top of the rake just under the string. That gives you an even 30 mm thickness for you to screed on if you use the 36" rake from toolstation and boggo 50 mm Marshalls blocks.

Grass seeds have of course all washed / blown into one corner of the garden. Much less successful than the blocks!


Cost wise for 38.5 m^2:

1x 8 wheeler muck away and 1x 8 wheeler of sub-base: £600
Man with mini digger for 1 day: £240
Sand: £150
Blocks: £550
Cement: £20
Sand: £20
New phone because I bloody boil washed the old one whilst laying this: £250

I'd have paid 2-3x that for a bodge job around these parts (Cambridge) and 3-5x for somebody to do it properly. And wouldn't have lost 4 kg in the process. Or developed serious respect for the guys that get up EVERY morning and do this.

[Tony McC]

Bloody hell! Them's BIG pictures!!!

Good job - a few naughty cuts but as long as you're happy, it's a credit to you and all your hard work.