Patio nightmare - Laying sawn polished sandstone

[samk]

Hi there,

I am having a nightmare laying sawn polished indian sandstone
on my base. Getting each stone level can take up to 10 go's and the worst stone took nearly an hour to get right.

I must be doing something wrong as I am pretty hell bent on doing this (well) and have barrowed nearly 25 tonnes of materials through my side gate (either taking out or bringing in), but am loosing the will to continue.

Also, after 24 hours i was inspecting some (at the time) perfectly even and firm stones and heard a horrible grinding noise which is happening cos there is some movement.

I'd really appreciate any comments on what I can change before attemting to lay the remainging 20sq meters.

THe basic details are:


1.Hardcore base (crushed concrete and building debris) - 1-2 inches - on already very compacted clay.

2.MOT type 1 - 5 tonnes - about two inches (endured heavy rain on many occasions before several passes with a wacker plate.

3. Bound bedding (9 parts sharp sand - 1 part cement) - mixed with a little water so the material is damp - but not wet.

4. Build a frame out of 4X2 to make accurate levels and be able to screed.

5. I have been laying the stones close together (a few joins are tight and touching) and tapping them into position with a rubber mallet) then jumping up and down in the middle to ensure they are firm.


Apart from the horrible grinding noise on stone that were firm when I laid them, it is clear that the stones are not bonding to the bedding at all (I thought they did have to - but am not so sure now).

I have a horrible feeling that the bedding mixture has failed and need to be done again!

Does anyone have any advice?

Thanks in advance for any replies

[lutonlagerlout]

9:1 is way too weak sam
5:1 is more like it
plus your bedding sounds massively too dry
plus theres no sbr in the mix

barrowing and digging is a lot less skilled than laying, none of us here got it right first,second or even third go

LLL

[samk]

Thanks LLL,

5:1 - check
SBR - have heard the term - will find out - check
wetter mixture - check


The laying sure is skilled - as opposed to digging and smashing - still starting to feel like Jean De Florette though!

Sam

[Bob_A]

A few places do SBR.
B&Q and Screwfix are probably the best known but you can it delivered for free from here
http://www.toolstation.com/documents/search/index.html?searchstr=sbr

Took me a long time to do my patio, the smaller flags weren't too bad but some of the larger 900x600's took several goes and took ages.
Although the pro's laugh I found this helped a bit.
http://ext.pavingexpert.com/cgi-bin....npecked

[samk]

Thanks Bob,

So I think I am set to lay the rest of the stones, but I have the problem of what to do with the existing stones. Any comments from a pro as to what they would do in this situation would be really appreciated (I know the pro's would probably not get in to this situation - but anyway).

The state of play is:

10 sq meters of stones down (roughly 30 of the different sizes)
30% are very slightly moving (not discernable to eye - mostly - but make a faint grinding noise or a tapping when i stand on certain bits (still can't understand how this happen - I was SO careful)

I have taken one up and the original mix (9 sharp, 1 cement - moist) - has gone hard.

Ripping the whole lot out and starting again is going to be alot or work as breaking/scraping my original mix out will take out some of my MOT - so i ll need more - and maybe to hire the wacker again - plus other problems with a manhole in the middile of the area where stones have been nicely cut to fit round)!

So - I am hoping to fix/salvage what I have done.

My three main ideas are:

1. take up the stone - chip/scrap out a bit of the oringal mix (that has gone hard) and put some more (better) moist/wet mix down and reset the stones.

2. Take up the stones - and very carefully sprinkle pointing/very fine sand where the void is and relay

3. Do number one or two - but to paint some sticky stuff maybe pva or sbr (is that right?) on the underside of the stone to stick to the now hard base (and little bit of dry sand/moist mix). - or even use something like tiling grout - they are only 20mm thick!


I am thinking that if one stone can be fixed effectively then 10 can - even if they take an hour each - it will save me ages compared to a full rip out/start again job.

I can get a photo if that give anyone a better idea,

thanks again for any help - I am really at sea with this!

[GB_Groundworks]

1 is the only option

[samk]

Thanks GB!

[samk]

Hi All,

OK so with 24 out of 37 stones not solid they all have to come up and i will have to start again completely.

I ll maually scrape out the bedding and make sure anything thats left is packed down with a manual thumper.

Before I go again this weekend, just want to make sure that my plan is ok;

Any comments/ critisms of plan would be greatly appreciated.


Mix;

5:1 sharp cement
will do a couple of sample mini mixes with 4:1:1 sharp/builders/cement - and leave overnight to see which is best.
Will get some Cementon SBR and add to mix - (not quite sure how much but to be safe will be quite liberal)

Will use mixer to mix dry ingredients well before adding SBR and water.
Mix will have consistency of mash potato and will stay in ball in hand if I squeeze it.

Will individually bed each stone, buttering up the mixture with a mini rake, then tamping down with a maul till in place.

Will wet each stone on the underside before laying.

Will not paint underside of stone with SBR (as discussions on this forum seen to have concluded there is no point).

Will leave 4mm gaps between stones (using tiling spacers)

Will tap round the stone with various impliments to make sure there are no hollow bits.

As stones are only 20mm thick will make sure that any bits of mix that have squeezed up the gaps to much are remove so I leave at least 10mm plus for pointing?

After finished session will cover stones with tarp and not set even a toe on them for 48 hours.

After solid will point.

Do not want to cut any corners on this - was going to use easipoint - with 4mm gaps - is there anything else I should be using in this situation.

OK - thats the plan!


ps the stones are - Bradstone - fossil buff (varying sizes)

Will ask about sealing when its down.

Thanks again for comments so far - and any further ones - is all greatly appreciated!

[lutonlagerlout]

sam you have to add ingredients to the water/sbr mix
if you do it the other way round it wont mix correctly
about 50-75ml of sbr per barrowful,but follow the manufacturer's instructions

LLL

[Bob_A]

Wouldn't you mix the sbr/water before hand.
Put half the sand in the mixer with some water, add the cement followed by the rest of the sand with the required water?

Sam
You say your flags are different sizes, are you sure 4mm gaps will work.
I could be wrong but I thought many manufacturers sized their flags so that the gaps are 10mm?
Have you designed your layout beforehand?

[pcdoc]

did you say you butt jointed some of the tiles?

I'm pretty sure thats a no-no for polished 22mm polished sandstone tiles- certainly thats the instructions I got with mine. I believe 10mm mortar joints are more appropriate.

Feel free to correct me if I'm wrong, people (I'm a keen diy'er- not a paving pro).

-Michael.

[samk]

i think some mistakes have been made so far.

i can 't see how 10mm gaps will work as the tiles fit perfectly when there are very small gaps - 2-3 mm.

i was going to take up the existing 10 sq m (out of 30) that I laid to correct and re-do from the start due to the fact they have nt stuck, but having checked today the 10:1 dryish mix I used is absolutely rock solid - and will involve breaking this up and relaying and wackin MOT - I just don't have it in me to do this now!

The plan - rightly or wrongly to salvage this is to take the non-solid ones up and use a slurry with SBR (or may be some self levelling screed) to stick them down.

This type of approach has to be worth a try!

Does anyone have any advice on this?


Also if there is an expert in the cambridge area who is free for a couple of hours of consultancy tommorrow arvo - I'd been keen to do a deal - if someone thinks they can give any valuable guidance (07919 377941).

I just need to make the best of a bad situation!

[Bob_A]

This forum is called 'Paving Expert' not 'Paving That'll Do' so you won't get the pro's advocating anything other than a fix that will be 100%.
As a DIyer I do take my work seriously but as I do not have a reputation to uphold I can will be bold and say give it a go and see what happens.
Check out one of my recent posts . I used sbr/cement recently on a handful of flags but then they were not true rockers.
Trevski cured some minor problems in a similar manner.
Like I say this is 'Paving Expert' and I've had great advice from the experts on this forum to which I'm a thankful.
So if your flags are that bad then take the experts advice, it's your call

[Bob_A]

i can 't see how 10mm gaps will work as the tiles fit perfectly when there are very small gaps - 2-3 mm.

You may well be right but I would double check.
10mm is normal, 2-3mm seems too tight, that'll make jointing difficult, flags touching in some places that can't be right.
If you'd said 5-8mm then that would sound plausible.
I'd seriously get a second opinion on this.

[samk]

Thanks Bob but surely a pro may have some ideas of how to salvage without just saying - start again at any cost!

If there is a professional contractor out there who can help, I am keen to do a deal for;

1. Sorting out what I have already laid - if this has to be completely taken out and started again - then thats what it ll have to be (10 sq meters), but it does seem ott.

2. laying the remainging 20 sq meters.

i did really want to get this done myself - but I think there does come a point when u have to surrender.

Sam - cambridge - 07919377941.