Fall, buildup and drain away - Patio log...

[zzr-matt]

Just going to start taking up my old split level patio which falls towards the house and replace it with something a little nicer looking. I think we will be using something like Bradstone Natural Sandstone but thats only from pictures on the web, will be going to view berfore buying obviously.

First question is the fall. The area will form a rectangle which is nominally 5700mm x 3000mm. The 5700mm edge will run along the back wall of the house with the 3000mm extending away. I think from what I have read if I could aim for a fall away from the house of around 55mm over the 3000mm distance this would give me a gradient of around 1:54 which should be ample for draining and still be usable by people? Would I need extra fall across the width or am I ok to proceed only falling away from the house?

Part of the area needs to be built up by 75mm or so. Should I just barrow in a load of MOT type 1 and compact it down for this?

There is a soakaway to one side of the patio and I have some lengths of ACO drive drain in the garage. Does this look a bit industrial at the edge of a patio or is it ok once the glavi finish has weathered in a bit?

[lutonlagerlout]

everything you have said sounds fine matt
the fall the subbase,the drains
the aco is a personal choice,i like the galv finish some dont,but at least you can clear it out
LLL

[zzr-matt]

Thanks LLL, I think I will have to lay the galvi out and see if its too harsh to my eyes or not.

I've come up with a few more questions...

1. I was going to build a step level with the DPC under my french doors. If I'm using something like the bradstone flags can I get away with not back filling the step and just supporting it at the front and back edge so as not to cause a bridge of the DPC? My gut feeling is no as this will not offer enough support to the flag so I was going to leave something like a 75mm gap between the infill in the step and the house and maybe give the wall in the area a coat of liquid DPC. Does that sound like it would be ok?

2. Are there any particular tricks to paving up to the wall part of the step with out having to fill the gap with a slither cut of flag like in this pic from the main site:


I guess I could just get the grinder out and cut down the flags that go against the house to move the actual patio in towards the house.

3. Would you guys normally build the step out of the same bricks as the house or something to match the paving?

4. I'm going to add an edging course of some kind which will blend into a mowing strip around the lawn. Any suggestions on what would look nice against the sandstone flags?

[lutonlagerlout]

matt
1 normally this is ok as long as the step falls away from the door,you can put dpm behind it for peace of mind but do not leave a gap,it will attract all sorts of deitritus

2if you are really careful you can build the step on top of the lower flags (pros do this)

3 its your choice i tend to use stocks or engineering bricks on steps for robustness and longevity

4 blue clay pavers (have this detail in my own garden)

LLL

[zzr-matt]

Thanks LLL, I've got a bucket of liquid DPM left over from my shed. Is it ok to use that or is some DPM sheet better?

I've got a pattern for the layout but due to how the gaps work out some will be at 10mm, 15mm and 20mm. Is that acceptable?

I may try and get a row of the same thing I use as the edging course in at the bottom of the step.

Heres a quick sketch of the vague plan:


Not sure how you guys manage all this manual work day in day out. Its taken me the last 6 months to replace the fence, build a gate and build a shed and I'm wrecked! lol


Part way through the cladding phase, not in its final location but you can see the level I need to bring up!

[Tony McC]

1 - If, on the Steps page you move down 3 images from the one posted above, you'll see a 3D schematic for how a 'hollow' step can be constructed at a doorway.

2 - better setting out could have avoided that nasty little slip, as could in-board cutting, but the installer reckons this is what the client requested.

3 - Risers are normally chosen to match the house or garden walls

4 - More sandstone, a contrasting limestone or, as LL says, clay pavers.



Edited By Tony McC on 1295950603

[zzr-matt]

Thanks Tony

The only query I had with the hollow step construction was if it would provide enough support for some of the thinner flags available?

If building the risers out of bricks to match the house is it worth introducing a DPC into the riser to stop spalling of the bricks over time? A retaining wall at the front of our property has suffered quite badly with this in 25 years its been up!

[lutonlagerlout]

I very rarely do a hollow step construction
I Tend to build the footprint on a 9" by 13" strip footing
225mm brick work then fill the void with leanmix and or hard core
then build the second step and fill that with leanmix and on and on
cheers LLL

[Tony McC]

Although I'd tend to agree with LLL that a solid step is the preferred construction, if you're using the hollow option, the strength of the tread paving will determine how many supports you need inside the structure. The thinner the flag, the more support required.

The question of a dpc in the riser is similarly impacted by your choice of materials. If you use a good FL rated brick, then damp shouldn't be a problem, but if they are porous facings, then it might be worth considering. Personally, I'd use engineering brick for the risers, if at all possible.

[zzr-matt]

Thanks Tony! I obviously had some kind of brain fail with regard to forgetting that I could just add extra supports!

I may just go for grey engineering bricks as it sounds like the safest option.

[lutonlagerlout]

grey engineering bricks

never saw these??
blue or red normally matt?
LLL

[zzr-matt]

Ah they looked grey, but on closer inspection they are called blue!

[zzr-matt]

Well I lifted all the old flags today and removed all the weak mix building sand and cement that had been used to bed the flags onto. I mashed up the old flags with a club hammer as its cheaper than going to the gym and I'm left with this:


The flags have so far only broken down to around a max size of 100mm so a fair way off of MOT1 20mm size. I'm currently around 150mm under finished paving level with this non compacted hard core so if I allow 50mm for flags, 50mm for bedding I've still got 50mm to come up.

I've got no problem with chucking everything I have there in a barrow and taking it to the tip but I thought I would ask if you guys think it would be ok for patio use to wack this lot with a plate then wacker down MOT1 over the top before the bedding layer? Would we mainly be talking settlement issues?

[lutonlagerlout]

that would be acceptable matt IMHO
cheers LLL

[zzr-matt]

Thanks LLL. I realise its not 100% ideal. What sort of size wacker would you guys normally use. I had a quick peak at HSS hire and they do a medium one which is 82kg which applies a 16kN force in the correct ball park or do I need a proper 130kg machine?