Hi all,
This is my first post and my thanks must go out to Tony for a great web-site.. well done! Ok, I have read through most of the pages I need to and I have few things I'd like to clarify. Apologies if I ask stupid questions - I know most answers are on the site but I may have missed or misunderstood some of it, so I just want clarification.
I intend to lay a patio and some decking in my new garden. At present, part of the intended patio area is covered in a concrete layer, some is covered in gravel and the remainder in square cheap patio flags. All of this will be removed prior to laying the new patio. The patio will undergo normal walking load and maybe a table and chairs but nothing more. Total area will be 43 square metres in a L shaped area.
The patio will be riven flags, probably mid priced but I'm not sure where from or what manufacturer (anyone recommend any merchants in Tyne & Wear?). I plan to use either 3 sizes (600x600, 600x300, 300x300) or a similar 5 size random pattern.
My question is about what type of sub-base, if any, I require. The flag laying page says that a patio does not require a sub-base (except in soft areas that may require filling). I am unsure at present what is under the concrete, gravel and old flags, so don't really know about what type of soil etc. Any help in this area is appreciated. It may be that I have to remove all the old stuff prior to making a decision.
With or without a sub-base, I'll need a 50-75mm layer of bedding right? The riven flags are pre-fab not natural so should be pretty even in depth. Also the maximum size will be 600x600. Does this mean I can go for a screed bedding rather than individual? In either case, what do you recommed for the bedding? Pure sharp sand or a mix?
Finally, jointing. I've seen various sites which say with riven flags you should use a mortar joint, but others say a dry sand joint is ok. Any opinions on this?
Once I know what sub-base (if any), bedding and joints I'm going to use, I can start using the calculators to work out how many tons of stuff I need!
Oh, one final thing. My patio will run up to the new decking which will be about 6 inches off the ground. Is it better to run the patio slightly under the decking frame and then deck clad down to the patio?... or the other way round.. or maybe it doesn't matter. Anyone done this?
Thanks in advance for any advice.
Cheers.
Sub-base & joint advice for garden patio
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73-1093879373
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84-1093879891
I hope I'm not too late - been in Ireland for a few days...
The sub-base - this is NOT necessary beneath a pedestrian-only path or a patio, unless there's an issue with the condition of the sub-grade (such as being soft, spongey or claggy), or if levels are being built-up. If you have a reasonably firm sub-grade, and the bedding thickness is not going to be more than 50mm, then a sub-base is not required.
Next: the bedding. This should not exceed 50mm. Ideally, it should be 35-50mm, and should consist of a sharp sand or a sand+cement mix. For the type of flag you're planning to use, I'd opt for a 10:1 semi-dry mix. Some contractors prefer a damper mix (or even a wet mix!) but I find I get best results using a semi-dry consistency.
75mm is too much - the bedding is a weakness in the structure (less so when a cement-bound bedding is used) and so we don't like to use depths of more than 50mm if at all possible.
As for laying, as these are a wet-cast product, it's unlikely that the screed-bedded method will be suitable. Although the flags may look fairly regular to the eye, once you've prepared a screeded bed and laid them down, the differences in thickness become much more apparent, so you're faced with having to supplement the bedding beneath the thinner flags, or not compact them as much as they should be. At the end of the day, I think you'll find that Individual bedding is the best option for this type of flag.
Pointing - I don't give a Donald Duck what other sites or anyone else says - dry sand jointing with this type of flag is a crime. It will disappear in a few weeks and then the joint will be colonised by weeds. The only effective joining is to use a mortar pointing. You could consider one of the frighteningly expensive polymeric sands, but, I still believe mortar pointing is the best option.
Finally, the decking. You wonder whther it's best to run the new paving under the decking and then nail on extra bits of stick to complete the deck. It probably is, but, if this were my job, I'd lob all that bloody decking onto a nice bonfire, chuck in a few spuds and toast some sausages on sticks. Decking and the climate of the soggy British Isles just don't mix. ;)
The sub-base - this is NOT necessary beneath a pedestrian-only path or a patio, unless there's an issue with the condition of the sub-grade (such as being soft, spongey or claggy), or if levels are being built-up. If you have a reasonably firm sub-grade, and the bedding thickness is not going to be more than 50mm, then a sub-base is not required.
Next: the bedding. This should not exceed 50mm. Ideally, it should be 35-50mm, and should consist of a sharp sand or a sand+cement mix. For the type of flag you're planning to use, I'd opt for a 10:1 semi-dry mix. Some contractors prefer a damper mix (or even a wet mix!) but I find I get best results using a semi-dry consistency.
75mm is too much - the bedding is a weakness in the structure (less so when a cement-bound bedding is used) and so we don't like to use depths of more than 50mm if at all possible.
As for laying, as these are a wet-cast product, it's unlikely that the screed-bedded method will be suitable. Although the flags may look fairly regular to the eye, once you've prepared a screeded bed and laid them down, the differences in thickness become much more apparent, so you're faced with having to supplement the bedding beneath the thinner flags, or not compact them as much as they should be. At the end of the day, I think you'll find that Individual bedding is the best option for this type of flag.
Pointing - I don't give a Donald Duck what other sites or anyone else says - dry sand jointing with this type of flag is a crime. It will disappear in a few weeks and then the joint will be colonised by weeds. The only effective joining is to use a mortar pointing. You could consider one of the frighteningly expensive polymeric sands, but, I still believe mortar pointing is the best option.
Finally, the decking. You wonder whther it's best to run the new paving under the decking and then nail on extra bits of stick to complete the deck. It probably is, but, if this were my job, I'd lob all that bloody decking onto a nice bonfire, chuck in a few spuds and toast some sausages on sticks. Decking and the climate of the soggy British Isles just don't mix. ;)
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73-1093879373
Thanks for the detailed reply Tony!
Ok, I'll check the whole sub-grade after lifting the concrete, gravel and old flags. Hopefully it will be quite firm allowing me to skip the sub-base. Bedding will be 35-50mm 10:1 semi-dry mix and flags will be laid using the individual bedding method. Mortar pointing will be used.
As for the decking, I'm inclined to agree with you but my lass wants it! I suppose it does add different levels, texture and colour to the garden... and before you say it... I know I could achieve that with stone!
One final question. I'm new to this and will be working considerably slower than a contractor or expert. I can prepare and level the sub-grade all at once (43 square metres), but how should I approach the bedding. Should I level the bedding across the whole site first and then start laying - bear in mind this will take me several days of laying... or should I only lay the bedding one section at a time. Call me stupid, but if I do the whole lot and it rains, the cement mix will go off won't it?!
P.S. Is their any formula for working out flag quantities for a random 3 size pattern (600x600,600x300,300x300)?
Ok, I'll check the whole sub-grade after lifting the concrete, gravel and old flags. Hopefully it will be quite firm allowing me to skip the sub-base. Bedding will be 35-50mm 10:1 semi-dry mix and flags will be laid using the individual bedding method. Mortar pointing will be used.
As for the decking, I'm inclined to agree with you but my lass wants it! I suppose it does add different levels, texture and colour to the garden... and before you say it... I know I could achieve that with stone!
One final question. I'm new to this and will be working considerably slower than a contractor or expert. I can prepare and level the sub-grade all at once (43 square metres), but how should I approach the bedding. Should I level the bedding across the whole site first and then start laying - bear in mind this will take me several days of laying... or should I only lay the bedding one section at a time. Call me stupid, but if I do the whole lot and it rains, the cement mix will go off won't it?!
P.S. Is their any formula for working out flag quantities for a random 3 size pattern (600x600,600x300,300x300)?
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84-1093879891
Well, if your lass wants decking ..... she knows where the hammer and nails are! ;)
Returning to talk about real, proper, safe surfacing, when you come to lay the flags, just mix up the bedding one barrowful at a time and spread that. If you use a half-barrow of grit sand with cement, this should cover somewhere about 2-3 square metres at a time, which, for a competent DIYer is around an hour's work.
There is no 'official' equation for calculating quantities for a 3-size random mix, but if you reckon on using a ratio of 1:1:1, then one of each size covers 0.63 square metres (roughly 2/3 of a metre) so your 43m² job would need 43 ÷ 0.63 = 68 of each - call it 70 for wastage.
However, this ratio gives a fairly regular-looking "random" layout, and I would tend to edge towards using more of the biggies and less of the tiddlers, say 1.25:1:0.75
Returning to talk about real, proper, safe surfacing, when you come to lay the flags, just mix up the bedding one barrowful at a time and spread that. If you use a half-barrow of grit sand with cement, this should cover somewhere about 2-3 square metres at a time, which, for a competent DIYer is around an hour's work.
There is no 'official' equation for calculating quantities for a 3-size random mix, but if you reckon on using a ratio of 1:1:1, then one of each size covers 0.63 square metres (roughly 2/3 of a metre) so your 43m² job would need 43 ÷ 0.63 = 68 of each - call it 70 for wastage.
However, this ratio gives a fairly regular-looking "random" layout, and I would tend to edge towards using more of the biggies and less of the tiddlers, say 1.25:1:0.75
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73-1093879373
Great, thanks once again for the speedy reply.
Now for the hard work in preparing the site ready for laying. I work full time so this will probably take a while. Might have it finished for the end of summer eh!?
Oh, I'm taking photo's along the way to give me a complete before/after. I might post a few when it's all done.
Thanks again for all your help and I'll update on progress as and when.
Now for the hard work in preparing the site ready for laying. I work full time so this will probably take a while. Might have it finished for the end of summer eh!?
Oh, I'm taking photo's along the way to give me a complete before/after. I might post a few when it's all done.
Thanks again for all your help and I'll update on progress as and when.
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73-1093879373
I started creating a task plan and a diagram for the patio and this has raised some more questions :
1) Edging. This is something I hadn't really thought about. 2 sides of the patio will meet with wooden garden fencing. 1 side will meet with turf/grass and 1 side will be against the house. I'm undecided what edging looks best with riven (if any) - most pics I see of riven flags don't seem to have edging. Any suggestions are welcome. If edging stones are used then my guess is that I should lay all of them first and then fit the flags within them.
2) As a diy'er I'll be laying a couple of square metres at a time. Should I point this with mortar as I go along or wait until the whole patio is laid? I know it's best to mortar whilst your buttering is still moist, but is this still the case if the patio isn't finished?
Thanks again for all the help and sorry for all the questions!
(Edited by InfAddict at 7:53 pm on April 16, 2004)
1) Edging. This is something I hadn't really thought about. 2 sides of the patio will meet with wooden garden fencing. 1 side will meet with turf/grass and 1 side will be against the house. I'm undecided what edging looks best with riven (if any) - most pics I see of riven flags don't seem to have edging. Any suggestions are welcome. If edging stones are used then my guess is that I should lay all of them first and then fit the flags within them.
2) As a diy'er I'll be laying a couple of square metres at a time. Should I point this with mortar as I go along or wait until the whole patio is laid? I know it's best to mortar whilst your buttering is still moist, but is this still the case if the patio isn't finished?
Thanks again for all the help and sorry for all the questions!
(Edited by InfAddict at 7:53 pm on April 16, 2004)
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84-1093879891
An edging is not necessary for flag pavements. You can have one, if you wish, but they are not essential, as they would be with, say, a bitmac driveway or a block paved area. They are decorative - so, if you do want to use one, choose something that you think complements the flags you're planning to lay.
And there's no need to lay them first - it's easier to make the edgings fit the flags, than make the flags fit the edgings. There are a few scenarios where ther edgings would be laid first, but, from what you've told us about your project, this is not one of them.
As for the pointing, even at the slower DIY pace, I prefer to see joints pointed as soon as you're sure of the alignment. If, for whatever reason, you decide to leave the pointing until all the flags are laid, this isn't the end of the world, and no real harm will come of it, but it does have a dis-spiriting effect: you've wore yourself out laying all those flags, and then you face spending 4 hours or more, hunched over on your hands and knees, pointing them all. I always thought it felt much better when, after laying the last flag, I only had a couple of metres or so to point - 10 mins work (if that) - and then I could clear up and get off to the alehouse. :)
And there's no need to lay them first - it's easier to make the edgings fit the flags, than make the flags fit the edgings. There are a few scenarios where ther edgings would be laid first, but, from what you've told us about your project, this is not one of them.
As for the pointing, even at the slower DIY pace, I prefer to see joints pointed as soon as you're sure of the alignment. If, for whatever reason, you decide to leave the pointing until all the flags are laid, this isn't the end of the world, and no real harm will come of it, but it does have a dis-spiriting effect: you've wore yourself out laying all those flags, and then you face spending 4 hours or more, hunched over on your hands and knees, pointing them all. I always thought it felt much better when, after laying the last flag, I only had a couple of metres or so to point - 10 mins work (if that) - and then I could clear up and get off to the alehouse. :)