Silver granite damp - What to do now?

[lutonlagerlout]

fire away LLL (see what i did there?)
although there are no secrets in the brew cabin
well none that i know of anyway
LLL

[Raga]

Please can the experts post their advise on how they should be laid
I've just had a chap quote £2k for relaying over 80sqm.
He'said he had never seen 20mm granite slabs
What worried more than the cost was he said he would lay them on 5 lines of mortar rather than the spots.
In my unqualified opinion this is not much better
Experts please help

[rab1]

you need a full morter bed, sharp sand and cement mixed and due too the type of stone would use a little srb in every mix.

[London Stone Paving]

Happy to answer any questions on the main forum my lord. That way others can also benefit from mine and Lutons considerable and extensive knowledge ???

20mm exterior stone IMO is unaceptable. More and more companies are doing it (some very reputable ones as well). Its mean and totally shortsighted and certainly not in the best interests of the customer

[London Stone Paving]

Please can the experts post their advise on how they should be laid
I've just had a chap quote £2k for relaying over 80sqm.
He'said he had never seen 20mm granite slabs
What worried more than the cost was he said he would lay them on 5 lines of mortar rather than the spots.
In my unqualified opinion this is not much better
Experts please help

To coin one of the gaffers phrases
"ask said contarctor if he would like a bucket of oats for his horse"
Then go and find a decent contractor who will do the job properly on a full bed of mortar. Its a complete fail. Also 2k is far too cheap for that type of work.

[lutonlagerlout]

Please can the experts post their advise on how they should be laid
I've just had a chap quote £2k for relaying over 80sqm.
He'said he had never seen 20mm granite slabs
What worried more than the cost was he said he would lay them on 5 lines of mortar rather than the spots.
In my unqualified opinion this is not much better
Experts please help

2k is too little to lift and relay
I dont know the site etc. but thats well short to do it right
as with all paving it needs to go on a full bed
LLL

[mickg]

>>>>>20mm exterior stone IMO is unacceptable
what are London Stone products calibrated to then Steve ?

[London Stone Paving]

>>>>>20mm exterior stone IMO is unacceptable
what are London Stone products calibrated to then Steve ?

Everything we supply is calibrated to 25mm, whether its riven or sawn. The issue I have with 20mm stone is when you factor in the tolerances of minimum +/- 2mm, some of the stone can be as thin as 18mm.

The industry standard at the moment is 22mm and thats what the majority of suppliers are importing. I still think 22mm is tight tbh but its a lot stronger than 20mm.

There are even some companies doing 15-22mm on Indian Sandstone. Again, not in the best interests of the customer

[The Late Lord Lucan]

Some of my questions have now been answered, with respect to thickness of stone.....
Having not finalised everything, I'm now feeling quite lucky that I'm still in a position to change my mind.
My plans so far are to lay the garden to patio, the linked picture shows a rough plan (Not all the joints shown on the darker borders are exact yet, I need to do some adjustments). To get an idea of size, the oblong shaped slabs depicted are based on the 600x300 slabs I was initially intending to purchase....... My garden is also, unfortunately, not a uniform size, although the left & right hand fence lines run parallel to the side of my house & conservatory..... & I think I may have had a few beers when the shed base went down 8 years ago...



The method planned so far is as follows.....
The garden will be excavated (already started) to allow for a MINIMUM of 100mm MOT Type 1 stone that will be compacted in layers to the final depth.
In turn, allowance has been made for 50mm sharp sand/cement mix for the bedding.... Is it highly recommended to use white cement here or is that not necessary??
Also, now being slightly better educated to the subject, a bond bridge will be used.....
You will note in the diagram, a strip of darker slabs running across left to right roughly half way between the shed & conservatory, there is a 'step up' here..... the section immediately in front of the conservatory will be approximately 150mm lower than the rest...... Not a lot I can do about this due to the levels outside of my garden.....
A drainage run will be placed immediately infront of the conservatory, again, not ideal, but options are limited, this will be the trough type drainage & run the full length of the front of the conservatory.

Ideally, I don't want any grouted joints..... is this a practical option? Is butt jointed the right terminology here?
The slabs appear to be cut very accurately, my personal choice aesthetically speaking is to have the least amount of gap, so my intention was to fit them tight & fill any left over hairline gaps with silver sand...... what are your views there?

After reading various threads, I am now leaning away from the 20mm thick stone & am considering the thicker option, so may have to redesign slightly as the slab sizes originally were 600x300 & 600x600..... I've not seen the 600x300 in a thicker slab.

The final finish will be with a breathable sealer to help prevent staining etc.

On a final note, I'm lucky in respect of the guys doing the work are a) well skilled & b) will do EXACTLY as they are told.... when they are not working in my garden, they are working on a site where they have to report to me...... so they really don't want to upset me.... :;):

From there, any comments, advice etc will be greatly appreciated.... I'd rather spend a little more time, & if necessary money now, than regret it later......

Regards,

TLLL (See what I did there LLL??)

[lana]

few comments straight off my head.
The slabs I did purchased are silver grey granite, 600X300 and they are 25 thick. I believe, the manufacture is Bradstone (while the company I purchased it from seems to be a retailer).

I also want to comment on no joints - I had the same idea and after the first two rows had to redo them and leave gaps. While the slabs are machine cut and appeared to be straight enough, when laid, they did had variable size, only slightly, within the standard, I assume, but 2 mm do make a difference in laying, so be warned.

[London Stone Paving]

The poachers turned into the gamekeeper. Great advice there Lana, you have learnt a lot from your time in the BC

Lord Lucan, Bradstone are a wholesaler but if you go on their webiste you will be able to find a stockist local to you

Following up on Lanas advice about the gaps. Butt jointing is a no no for 2 reasons. Firstly sawn paving is subject to minimum tolerances of +/- 2mm. This makes clean butt jointing very difficult and the slabs will be bumping into eachother. Also water should run off the surface of your patio to a drain or flower bed etc. If you have no pointing then it will dribble down the sides and could undermine the bedding layer

[lana]

Thank you, kind sir! *the poacher is blushing now*
Since this thread appears to become the most full assembly of information on grey granite slabs, can I please add yet another question related to the same. It might benefit others whoever may wander in in search of advice.

My slabs are finally laid where they should and the jointex is of more suitable natural colour. Today someone from the traid adviced my contractor to do the following:
1. seal the unpointed slabs
2. point them with jointex
3. seal them second layer

Their reasoning: when pre-sealed, the jointex won't be absorbed by the granite and won't re-colour them.

My concern: I understand that sealing is done when the slabs are completely dried. Last slabs in my patio have been laid on Sunday (i.e. about 48 hours ago or so) the slabs still look wet in places. would the sealing "freeze" the spots where they are? (my thinking is if the sealant prevents the moisture getting in, it won't let it out either?)

So basically, my question is: is the seal-point-seal technique worth bothering and if it can be applied to the stones that are not quite dry yet?

Here is the picture of the patio to explain which spots do I mean (and i can swear they are NOT spot bedded, I've been watching how he did it and it is full bed, so have no idea why the spots appear in this strange pattern)
lana's patio

[London Stone Paving]

Thats actually good advice. We always reccomend that if possible, paving should be sealed prior to installation. There are a few good reasons for this and one of those reasons is that pointing residue and general builders mess will not have as much of an impact on sealed stone

On to your question about sealing the paving before it dries. It all depends on the type of sealant you are using. Water based sealants for example have much less active ingredient in them and can be applied to damp paving. I would not reccomend them though because they break down much quicker from sunlight and general wear and tear. I would only reccomend dry treat and lithofin as sealants and would not touch anything else

Hope that answers your question

[lana]

Steve, thank you so much, as always, your responses are so helpful!

OK, I understand the disadvantages of water-based sealants. Since my contractor is willing to apply this technique and judging by the price of the sealant they mentioned, it is most likely water based kind, so if I'd say go ahead and do it this way, I'm, essentially, risking it less to discolour stones, yet improving the quality of grouting still. If the water based sealant needs to be re-applied in a year-couple of years time, what would prevent me to apply the dry treat next time I'll do it.

I think, I'm happy with this solution. Unless somebody tells it is not technologically correct.
thanks again for your input!

[The Late Lord Lucan]

How is everyone getting on with their issues with granite slabs?
I trust you have all managed to iron out the problems & have found satisfactory results?

My paving is now finished, not on time & not within budget.....
This was mainly due to us changing & adding to the scope of works, & partly because I was maybe extra fussy about the job & requested the guys doing the work to re-lay a number of slabs that I wasn't 110% happy with.
A slightly painful experience for all, but very well worth it in the end.
Below is a brief summary of how it was done. Hopefully this will be of use to someone else, the main point being, only because of the information found on this forum, & the help provided by others here, have I ended up with a garden that I am totally happy with & don't appear to have any issues with damp or discolouring at all.

The lads doing the work for me, as I previouslynexplained, were experienced workmen, but not particularly in paving. They gave me funny looks at times, seriously questioned the methods & I have no doubt called me a few names under their breath. However, they continued to do as requested, & now it's finished, they understand why it was done that way & are also very pleased with the results.

If I mention any brand names, this is purely to explain what I used, not to advertise..... I wouldn't have a clue if others were better or worse, they just appeared to have preference from others on here with far more experience..... & my results so far appear to have no problems with the finished garden.

Slabs used were bradstone silver granite & I think the other was graphite.
Sub base went down.... this finished up at a depth of 150mm minimum to maybe 250mm max.... this was due to change of scope & my miscalculations, but most importantly, it wasn't 'too thin' anywhere.
This was put down in layers & hammered down with a wacker plate.
Slabs were laid on a FULL BED of sharp sand/cement mix.... cement used was just your average bag of cement....
The back of the slabs were painted with a mixture of febond SBR & snowcrete...... I went with the white cement so that should any colour get sucked into the slabs, I wouldn't end up with dark patches on my silver granite...... This may have been a misguided choice, or one that has no gain at all..... but they are down, & I have no patches.....
One thing we did note was, the slabs I chose to pull up & re-lay (for varying reasons such as tiny chips or veins etc) were very hard to get back up where a good thick coat of this jollop had been painted on..... on a couple that were a bit thinly coated, they came up a lot easier..... so my personal opinion is don't be shy at getting that stuff on..... just wash any marks off the top face IMMEDIATELY.....
Against better advice, I went with a 5mm joint..... yes, this presented a challenge for pointing, but I got a guy with a lot of experience to come & do this. Whilst it was time consuming, he got it done.... properly..... & it looks fantastic.
I went for a black grout made from a sharp sand & cement mix... this left me holding my breath for a while, but again, it's down & there are no signs of any staining a month down the line.
I am now awaiting good dry weather to seal it, for which job I have gone for lithofin. Looking at the weather, this may be waiting for next year now........

Once again, thank you for all the help I found here, & hopefully this may help someone else...

A few pics below.... I'll try to get some with the finished pointing later when the rain stops....

Regards,
Andy.

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