DPC - I wonder where it is?

karlitob

Hi all

Need to locate the DPC for my patio build this summer. There’s an vent that’s about 130mm from the old hit of concrete patio that’s there.
The previous owner of the house built this extension himself we think sometime in the late 70s. It would be preferable if the DPC was above the vent as it would give me much more leeway to raise the ground to where I want it.

Any suggestions? Thank you.

Lumen

The DPC should be directly above the vent, but are you accounting for the fact that you need the ground level to be at least 150mm below the DPC?

Also, you don't want the possibility of a minor flooding spilling into the vent.

karlitob

Lumen wrote: »

The DPC should be directly above the vent, but are you accounting for the fact that you need the ground level to be at least 150mm below the DPC?

Also, you don't want the possibility of a minor flooding spilling into the vent.

Ground to top of vent brick is 300mm.
Ground to bottom of vent brick is 140mm

Understand the point of spot flooding.


Was thinking of the dry-arrangement set up on lacing expert. I do need to come up a little bit to have sufficient fall. Ideally to the bottom of the vent brick.

https://www.pavingexpert.com/dpc01

standardg60

Imo without knowing for sure where the Dpc is your best solution is to knock out the concrete and lay the patio to the same level.
You won't have to bother with a dry arrangement or need a big slope on the patio then.

karlitob

standardg60 wrote: »

Imo without knowing for sure where the Dpc is your best solution is to knock out the concrete and lay the patio to the same level.
You won't have to bother with a dry arrangement or need a big slope on the patio then.

Thanks.

Need a bit more height to get sufficient fall.

standardg60

karlitob wrote: »

Thanks.

Need a bit more height to get sufficient fall.

Can you post a pic of the whole area to be paved?
Patios don't need to have a big fall, if at all.

karlitob

standardg60 wrote: »

Can you post a pic of the whole area to be paved?
Patios don't need to have a big fall, if at all.

I want a 1:10 fall. Over 10m that’s 100 mm. it’s a 100 sq m patio (10x10). So need a fall on both sides. It’s a fairly flat area. I’ll try and get some pics up later.

For some reason, a patio company wanted to bring it up 5 inches. Bit shocked at that.

standardg60

karlitob wrote: »

I want a 1:10 fall. Over 10m that’s 100 mm. it’s a 100 sq m patio (10x10). So need a fall on both sides. It’s a fairly flat area. I’ll try and get some pics up later.

For some reason, a patio company wanted to bring it up 5 inches. Bit shocked at that.

Let me guess, they advised 2-3 inches of hardcore followed by requisite layer of concrete/grit without having to go to the trouble of excavating whatever soil/subsoil is already there?
Laying a patio to fall in two directions is not easy, i would go level with the house and fall away from it only. I'd be inclined to say too (even though it sounds scary), that if you've two directions of run off that it would be fine to lay it level in both directions, but i'll wait to see your pics.

Lumen

karlitob wrote: »

I want a 1:10 fall. Over 10m that’s 100 mm. it’s a 100 sq m patio (10x10). So need a fall on both sides. It’s a fairly flat area. I’ll try and get some pics up later.

For some reason, a patio company wanted to bring it up 5 inches. Bit shocked at that.

Unless I've having some kind of pre-geriatric brain spasm, 1:10 over 10m is 1m of fall.

And if it was me, I'd lay a patio with zero fall and a permeable base and jointing. But that's probably controversial.

standardg60

Lumen wrote: »

Unless I've having some kind of pre-geriatric brain spasm, 1:10 over 10m is 1m of fall.

And if it was me, I'd lay a patio with zero fall and a permeable base and jointing. But that's probably controversial.

Yes 1:10 is Tour De France stuff!, but assumed the OP meant 1:100:D

Agree though, Zero fall is fine, even without the permeability, i lay all patios that way, but bound to be controversial alright.

karlitob

Lumen wrote: »

Unless I've having some kind of pre-geriatric brain spasm, 1:10 over 10m is 1m of fall.

And if it was me, I'd lay a patio with zero fall and a permeable base and jointing. But that's probably controversial.

Jaysus my head is getting to me. Reading too much stuff on d’internet. 1:100.

I’m planning on laying porcelain. Guidance (expert paving and BS is 1:60) and the ‘experts on YouTube’ say 10mm fall in every 1m should suffice. Both say a non-permeable base is required as porcelain is a tile and as such needs a rigid sub base. Recommendations include a 50mm lean mix of 10:1 on top of 100 or so mm of 804.

Will gladly accept any comments.

karlitob

standardg60 wrote: »

Yes 1:10 is Tour De France stuff!, but assumed the OP meant 1:100:D

Agree though, Zero fall is fine, even without the permeability, i lay all patios that way, but bound to be controversial alright.

To be honest when I’ve worked out the levels on the 1:100 (thank you) it seems fairly steep to me.I’ve a concrete fence panel on one side. A 100mm height difference over 5 concrete panels seems fairly steep alright. But I wanted to follow the expert advice.

ted1

karlitob wrote: »

Jaysus my head is getting to me. Reading too much stuff on d’internet. 1:100.

I’m planning on laying porcelain. Guidance (expert paving and BS is 1:60) and the ‘experts on YouTube’ say 10mm fall in every 1m should suffice. Both say a non-permeable base is required as porcelain is a tile and as such needs a rigid sub base. Recommendations include a 50mm lean mix of 10:1 on top of 100 or so mm of 804.

Will gladly accept any comments.

The tiles are non permable. Don’t see why you need a non permable base.
You do need to prune the tile with SBR. The mix seems a bit of. I was recommended 5:1.

I just finished mine. If I was to do it again I’d rent a mixer.
Get yourself a good diamond blade for cutttng the tiles. Do a light cut initially, you can turn use that as a guide.

karlitob

ted1 wrote: »

The tiles are non permable. Don’t see why you need a non permable base.
You do need to prune the tile with SBR. The mix seems a bit of. I was recommended 5:1.

I just finished mine. If I was to do it again I’d rent a mixer.
Get yourself a good diamond blade for cutttng the tiles. Do a light cut initially, you can turn use that as a guide.

The suggestion is that the sub base (804) is not a fixed substrate, the lean mix is (whacked and levelled). You then put a mortar bed of 5:1 on top of that along with a slurry primer as you suggest.

Any pics. Fair play.

standardg60

ted1 wrote: »

The tiles are non permable. Don’t see why you need a non permable base.
You do need to prune the tile with SBR. The mix seems a bit of. I was recommended 5:1.

I just finished mine. If I was to do it again I’d rent a mixer.
Get yourself a good diamond blade for cutttng the tiles. Do a light cut initially, you can turn use that as a guide.

Yep 5:1, internet experts eh:)

karlitob

See from minute 3 ish

https://youtu.be/xAJZAeO4ySw

ted1

karlitob wrote: »

The suggestion is that the sub base (804) is not a fixed substrate, the lean mix is (whacked and levelled). You then put a mortar bed of 5:1 on top of that along with a slurry primer as you suggest.

Any pics. Fair play.

Just remembered I need to life the path to the shed replace with tiles. I’ll leave a gap between them so will just dig out a square and lay on sand.

I’ve tidied the garden since the photo.

https://imgur.com/gallery/KKD49GH

Another key tip is to avoid letting the tiles touch when laying. Even if just lifting Do as to level it. Tiles on tiles cheap easily.

I didn’t use PQC. I didn’t see it on any other sites. All said , hard core base with mortar straight over.

karlitob

standardg60 wrote: »

Yes 1:10 is Tour De France stuff!, but assumed the OP meant 1:100:D

Agree though, Zero fall is fine, even without the permeability, i lay all patios that way, but bound to be controversial alright.

Hi all

Thanks for your advice on this thread. Much appreciated.
Could I ask you and lumen more on this point.

I’m trying to work out my levels at the moment. I’m putting in porcelain. Do you really think no fall is ok? What about run off of water?

Thanks for your time in responding.

standardg60

karlitob wrote: »

Hi all

Thanks for your advice on this thread. Much appreciated.
Could I ask you and lumen more on this point.

I’m trying to work out my levels at the moment. I’m putting in porcelain. Do you really think no fall is ok? What about run off of water?

Thanks for your time in responding.

Regardless of whether you provide a fall or not you still need to think about run off (a level patio will still drain). I think you mentioned earlier that the garden rises away from the house, so natural run off into the garden may be an issue.

Are you planning on inserting a drainage channel linking to the storm water drain? This could be placed along the house wall or the end of the patio.

As for laying the patio flat, yes it's absolutely fine as water cannot pool on a level surface but bear in mind there is less margin for error as every tile must be level, whereas if you provide a slight fall slight discrepancies in the fall won't matter.

karlitob

standardg60 wrote: »

Regardless of whether you provide a fall or not you still need to think about run off (a level patio will still drain). I think you mentioned earlier that the garden rises away from the house, so natural run off into the garden may be an issue.

Are you planning on inserting a drainage channel linking to the storm water drain? This could be placed along the house wall or the end of the patio.

As for laying the patio flat, yes it's absolutely fine as water cannot pool on a level surface but bear in mind there is less margin for error as every tile must be level, whereas if you provide a slight fall slight discrepancies in the fall won't matter.

Thanks for that.

I’ve been ruminating about drains but since I planned for the fall to run away from the house - I didn’t think I needed it.

If water was collecting at the end of the patio - I thought I might put in a French drain, as the ground drains well. No water logging.

With porcelain - is there not a small margin of error for laying regardless of the fall (don’t mean that to sound smart)?

whizbang

My Porcelain patio is down about 1 month now.
The middle section; approx 4 * 2 (x600mm) tiles is as level as possible. The outer edges have a fall of just over 1mm for each tile, so thats only about 5mm for 3 x tiles, About 1:360. Thats plenty enough for the rain.
As mentioned above, the more level, the less margin for error. 0.5mm is noticable.

Just one thing starting to show, the dirt doesnt wash off easily if theres no fall..! TBH Its not a real problem as the porcelain doesnt really get dirty.

I have a fall away from house with good drainage so nothing else needed regards drains.
Any other way i would definitely put in a drainage channel.

karlitob

whizbang wrote: »

My Porcelain patio is down about 1 month now.
The middle section; approx 4 * 2 (x600mm) tiles is as level as possible. The outer edges have a fall of just over 1mm for each tile, so thats only about 5mm for 3 x tiles, About 1:360. Thats plenty enough for the rain.
As mentioned above, the more level, the less margin for error. 0.5mm is noticable.

Just one thing starting to show, the dirt doesnt wash off easily if theres no fall..! TBH Its not a real problem as the porcelain doesnt really get dirty.

I have a fall away from house with good drainage so nothing else needed regards drains.
Any other way i would definitely put in a drainage channel.

Thanks so much for taking the time to respond.

I might just put in a fall of 50mm or so from the house to the garden. If water collects at the threshold between the garden and patio I can put in a French drain.

Otherwise, I’m not sure how I would put in a fall on the drainage channel left to right, if the patio is falling back to front - as it were. In other words, I’m planning for the patio to be level left to right and fall back to front. If I put in a channel left to right how would I get that to fall?

irishbuzz

I'm fitting a porcelain patio shortly and will include a very gentle fall in it and have a slot drain channel to collect the runoff. They're a bit smarter looking for this application than the normal ACO channels.

standardg60

karlitob wrote: »

Thanks for that.

I’ve been ruminating about drains but since I planned for the fall to run away from the house - I didn’t think I needed it.

If water was collecting at the end of the patio - I thought I might put in a French drain, as the ground drains well. No water logging.

With porcelain - is there not a small margin of error for laying regardless of the fall (don’t mean that to sound smart)?

Your garden rises away from the house so the best and easiest option is to put in a drainage channel now and not worry about a french drain which can be more trouble than they're worth.
why not lay a channel along the house and then either lay the patio level or with a fall back to the house .It's very simple to connect the channel to the existing storm/sewage drain, i usually use half inch overflow pipe to connect the two.

karlitob

standardg60 wrote: »

Your garden rises away from the house so the best and easiest option is to put in a drainage channel now and not worry about a french drain which can be more trouble than they're worth.
why not lay a channel along the house and then either lay the patio level or with a fall back to the house .It's very simple to connect the channel to the existing storm/sewage drain, i usually use half inch overflow pipe to connect the two.

Thanks so much for the reply. Appreciate you taking the time to explain it. Want to get this right from the start.

I’m a bit nervous about laying back to the house so I’ll take your advice and lay level with a channel across the house.
Would it make any sense to put in a gentle fall away from the house and a channel drain at the house?

Can I ask another stupid question?

I’m planning on the patio being level (no fall) across the house. If I put a fall in the drainage channel would that look wrong? One end would be lower than the patio - it wouldn’t look flush?


Finally - did you mean a half inch pipe? Would you not need a larger diameter pipe to connect both.


Thanks again.

standardg60

karlitob wrote: »

Thanks so much for the reply. Appreciate you taking the time to explain it. Want to get this right from the start.

I’m a bit nervous about laying back to the house so I’ll take your advice and lay level with a channel across the house.
Would it make any sense to put in a gentle fall away from the house and a channel drain at the house?

Can I ask another stupid question?

I’m planning on the patio being level (no fall) across the house. If I put a fall in the drainage channel would that look wrong? One end would be lower than the patio - it wouldn’t look flush?


Finally - did you mean a half inch pipe? Would you not need a larger diameter pipe to connect both.


Thanks again.

Sorry, yes you're right, i meant 1 inch pipe, i connect it to the channel a half inch from the bottom to stop sediment flowing in.

It's perfectly fine to fall to the house with a drainage channel there and from what i remember you've plenty of scope to lay well below your vent/dpc level.
Defeats the purpose of it if you fall the patio away from the house though.

The drainage channel is laid level, like your gutters it doesn't need a fall, the water will still drain out of the pipe once it reaches that level.

karlitob

Sorry about the slow reply. Thanks very much for your response. Will take that advice.

Could I ask one other query?

My garden rises 250mm or so front to back. About ⅔rds down the garden is where is really starts to rise. I’m thinking of putting in a kerb of granite ~ 1000 x 200 x 100

Because of the height difference I’d really like to see all 200mm of the face of the kerb. I’ve read up all about kerbing and haunching and I’ve two questions

- if I put sufficient haunching at the back will it be strong enough if the grass is pushing behind it.
- if I have insufficient hancihing at the front - cos I want to see the granite - will it be wrong enough if the grass is pushing behind it.


Hope that makes sense. Thank you.


There’s a pic on this website which shows what I’m looking for. It steps up onto patio rather than grass but you get the idea.

https://www.mcmonaglestone.com/gold-granite-kerb-bush-hammered

karlitob

Just to add a photo to help

The yellow line is a block edging currently in place.

The black line is kinda what I’m thinking.

The blue line is where the block (which was an old greenhouse base) comes up.


I was also thinking if getting a coping stone and place it on edge.

Thanks all.

https://ibb.co/J7R2cRj
https://ibb.co/Ycndx5y
https://ibb.co/ZLLkvLh

karlitob

Appreciate any view on this. Thanks all.

Lumen

FWIW I would definitely not install the kerbing on edge, because it's unstable, so you're relying on the adhesion of the bottom and back-side of the stone to stop it from rocking when people inevitably use it as a step.

Of course you could mitigate this with various measures like bolting it to concrete behind the kerb, but TBH you're better off just building it conventionally (steps or whatever) as it'll look better anyway.

If you want to do it more cheaply just use stacked "sleepers" protected underneath and behind from ground contact.

karlitob

Lumen wrote: »

FWIW I would definitely not install the kerbing on edge, because it's unstable, so you're relying on the adhesion of the bottom and back-side of the stone to stop it from rocking when people inevitably use it as a step.

And this is the thing of course that I want to avoid.

Lumen wrote: »

Of course you could mitigate this with various measures like bolting it to concrete behind the kerb, but TBH you're better off just building it conventionally (steps or whatever) as it'll look better anyway.

If I understand you right, put concrete to the back of the kerb (a hauncing) and fix to that?



I agree about the steps, but its making the project much larger and expensive doing it that way.



I need to negotiate this rise somehow.

Lumen wrote: »

If you want to do it more cheaply just use stacked "sleepers" protected underneath and behind from ground contact.

Do you mean like a block sleeper wall behind and then this kerb in front of it?

——————————-

I'm putting in a porcelain patio close to the house with granite cobble border. I have a path going to the back of the granite with a granite cobble border. And I have borders at either side for plants which are kerbed in granite.I've attached a few pics of where the design is for this part of the garden; and I also have put in some ideas on how I would negotiate the rise. Are any of them anywhere near the mark?


https://ibb.co/HNrkmKD



Thanks for your time in replying.

Lumen

karlitob wrote: »

If I understand you right, put concrete to the back of the kerb (a hauncing) and fix to that? .

Maybe, but that's not how haunching works, it resists lateral movement through compression. What you're proposing isn't haunching, it's something else. It sounds bodgy.

As to the design details I don't really know, I just know from experience that relying on the adhesive qualities of mortar on stone is a bad idea.

karlitob

Lumen wrote: »

Maybe, but that's not how haunching works, it resists lateral movement through compression. What you're proposing isn't haunching, it's something else. It sounds bodgy.

As to the design details I don't really know, I just know from experience that relying on the adhesive qualities of mortar on stone is a bad idea.

Thanks Lumen. Appreciate your time. I had read up a bit on retainers and thought I was onto something - but doesn't seem correct. https://www.pavingexpert.com/featur06



I feel a little stuck now. I don't really know how to progress.



I'm sure I'll think of something.

Lumen

karlitob wrote: »

Thanks Lumen. Appreciate your time. I had read up a bit on retainers and thought I was onto something - but doesn't seem correct. https://www.pavingexpert.com/featur06

Ah I see, it's haunched from both sides. That looks clever but complicated!

karlitob

Lumen wrote: »

Ah I see, it's haunched from both sides. That looks clever but complicated!

Still. It's not exactly what I'm looking for. I'd like to see the full 200mm of the granite kerb. Kinda like in the pics. Just no idea how to do it. Or at least it looks straightforward - but whats the best way to fix and ensure it never ever moves.



This kinda thing is what I'm looking for.

Lumen

karlitob wrote: »

Still. It's not exactly what I'm looking for. I'd like to see the full 200mm of the granite kerb. Kinda like in the pics.

Those kerbs are set below the level of the paving. They're not showing the full face.

karlitob

Lumen wrote: »

Those kerbs are set below the level of the paving. They're not showing the full face.

Understood. Any idea how their fixed?

That’s why I was thinking about 50mm haunch to the front and 175mm to the back on a bed or 150mm.

I’m not exact one this pic but maybe a somewhat close?
https://www.boards.ie/vbulletin/attachment.php?attachmentid=557487&d=1625337921

standardg60

karlitob wrote: »

Thanks Lumen. Appreciate your time. I had read up a bit on retainers and thought I was onto something - but doesn't seem correct. https://www.pavingexpert.com/featur06



I feel a little stuck now. I don't really know how to progress.



I'm sure I'll think of something.

Imo a version of the link you posted should be fine, it's important to lay a wide foundation under the kerb so the rotational force of the ground being retained is spread out.
As for ensuring a good adhesive hold on the back of the kerb use a plasticiser in the mix. I always add it when laying patios too as it does the same job on the back of the paving.
Btw i use a few drops of washing up liquid, as good as anything.

karlitob

standardg60 wrote: »

Imo a version of the link you posted should be fine, it's important to lay a wide foundation under the kerb so the rotational force of the ground being retained is spread out.
As for ensuring a good adhesive hold on the back of the kerb use a plasticiser in the mix. I always add it when laying patios too as it does the same job on the back of the paving.
Btw i use a few drops of washing up liquid, as good as anything.

Thanks so much for that. Really appreciate it.

So wide foundation under the kerb but otherwise you don’t reckon I’m too far wide of the mark?

https://www.boards.ie/vbulletin/attachment.php?attachmentid=557487&d=1625337921

Thanks so much.

standardg60

karlitob wrote: »

Thanks so much for that. Really appreciate it.

So wide foundation under the kerb but otherwise you don’t reckon I’m too far wide of the mark?

https://www.boards.ie/vbulletin/attachment.php?attachmentid=557487&d=1625337921

Thanks so much.

Yep, that's fine, though I'd slope the haunch for drainage

karlitob

standardg60 wrote: »

Yep, that's fine, though I'd slope the haunch for drainage

Understood. Thanks again.

Feck this is hard. And I haven’t even started yet.

Appreciate all your help.

karlitob

https://www.boards.ie/discussion/comment/117546971#Comment_117546971

Hi there

getting someone to do the groundwork’s and I’m gonna do the laying.

my patio will be 10 x 10m; and I’ve taken your advice on this thread. Thanks so much. Level is fine as long as you have a way to clear the water.

would you have any guidance as to how many slots are needed. I was thinking one in the middle and one at the end of the patio. Would that sound correct to you?

I was planning on slot channels also which will drain into our sewage system (grey water) - so these slot channels have sumps or some sort of inspection and Clearqnce chamber.

thanks all. This thread has been very helpful.

standardg60

One at the end is fine, there's more than enough capacity to handle the rainfall we get here

karlitob

https://www.boards.ie/discussion/comment/117794701#Comment_117794701

Thanks so much. Grateful for your time.

karlitob

https://www.boards.ie/discussion/comment/117794701#Comment_117794701

Sorry to bother you once more.

In the middle of the patio I'm planning two l-shaped floating benches. There'll be a 1.5m gap between the two so you can walk up and down the patio. https://ibb.co/2kW310k

I think the rain might collect at the base of these walls so I was wondering if I should put the drain across the middle, in front of these walls - as you look from left to right in the picture; rather than at the end. Any view would be welcome.

I was thinking of slot channel drainage also, rather than the standard. But not sure of whats needed in terms of rodding access? Any view on this?