The Brew Cabin

Posted: **Sun May 12, 2013 8:40 pm**

Hi,

We bought some silver granite paving for our garden and had it installed as part of an extension project about 7 months ago. At the time it was finished we noticed damp patches around the paving but the builder suggested this would take some time to dry out. About a month after we sent an email to the supplier to ask their advice and their response was:

"This is normal as the granite paving can be quite absorbent and it will soak up moisture from the sand & cement mixture which they have been laid on and even from the ground underneath this mixture. It can take time for this to dry out, 2-3 weeks and in some cases longer.

Please be sure not to seal the paving until after it has dried out as this would effectively seal the moisture inside the slabs and prevent them from drying out."

Anyway, it is now 6 or 7 months later and we still have damp patches (it never went completely away). So I dropped another email to the supplier and they said:

"This is usually the case if the granite paving has not been laid on a full bed of mortar of there are uneven areas of mortar. When it rains granite will absorb water but this water will dry out in the sun. My advice would be to visit www.pavingexpert.com for an remedial options for granite paving."

So here I am. I am completely ignorant of paving, how it should be done, what you should do afterwards etc. All I know is the paving looks nice except for damp patches all over it. When it rains it dries unevenly and some parts never dry out.

Now, I am wondering if it was laid incorrectly or something like that, can I buy something to put on top of it that will make it look the colour when wet and therefore it will all look the same colour? Any other suggestions more than welcome, I am at a loss what to do.

Thanks in advance,

Matt

Posted: **Sun May 12, 2013 9:08 pm**

Hi Matt

Sounds to me like the granite has been laid on spot bedding. This is a spot of mortar in each corner and one in the middle. The spots will act as a wick, and pull moisture and cementitious material through to the surface of the granite. This then causes the moisture patches

If the patio has been laid on spots, unfortunately its bad news. Are any of the slabs coming loose?
How is the pointing holding up?

Can you please post some photographs of the patio

Steve

Posted: **Sun May 12, 2013 9:23 pm**

When you say bad news does that mean nothing can be done?

Here is a picture not long after it was done, it isn't anywhere near as bad as this now but it does still have the patches in places.

Example

There isn't any pointing.

Thanks

Posted: **Sun May 12, 2013 10:00 pm**

Judging from your pictures Its not 100% spot bedding but its not a full bed either. Slabs laid on spots will usually start to loosen within a year of installation. You might get away with it though because the moisture marks indicate that there is a reasonable amount of mortar under the slabs. You will be stuck with the moisture marks I reckon

Posted: **Sun May 12, 2013 10:04 pm**

even though granite is a very hard surface its actually very porous and can act like a sponge

the issue you have is the granite has been butt jointed together with no joints hence the picture framing around each paving slab plus it looks like its been laid on a band of bedding around the outside of the flag and a strip down the centre or spots hence the dry area's and the damp area's

this will fade slightly as it dries when its not raining and show a 10mm - 15mm band around each flag but sadly will never completely go away

it can also occur if the granite has not been laid on a suitable sub base, ie 100mm minimum MOT type one to give drainage for the paving or if the existing ground is clay or not permeable so the water has no where to drain to

it can also occur if its been laid on a concrete base and then the granite bedded onto this surface, likewise there is no drainage hence the picture framing around each piece

in your case it "looks" like the granite has not been laid on a full bed and also butt jointed together, sadly the only solution is to take it up and relay it or to live with it

Posted: **Sun May 12, 2013 10:06 pm**

London Stone Paving wrote:Judging from your pictures Its not 100% spot bedding but its not a full bed either. Slabs laid on spots will usually start to loosen within a year of installation. You might get away with it though because the moisture marks indicate that there is a reasonable amount of mortar under the slabs. You will be stuck with the moisture marks I reckon

Is there anything I can put on top of it to try and get it to look a bit darker maybe, so it all looks wet and therefore not so contrasting between the two?

Oh, and is it supposed to have some kind of sealant on it? If so what?

Thanks again

Posted: **Sun May 12, 2013 10:07 pm**

mickg wrote:in your case it "looks" like the granite has not been laid on a full bed and also butt jointed together, sadly the only solution is to take it up and relay it or to live with it

Ah, that sounds expensive

Posted: **Sun May 12, 2013 10:22 pm**

just looked at the other photos on the above link (nice extension by the way

MOT depth looks fine from the photos, its the granite flags touching each other what act like a wick and the picture framing will never totally go away so be very careful if you are going to apply a sealer

Posted: **Sun May 12, 2013 10:28 pm**

mickg wrote:its the granite flags touching each other what act like a wick and the picture framing will never totally go away so be very careful if you are going to apply a sealer

So applying a wet look sealer wouldn't help? So my only choice is to start again from scratch?

Posted: **Sun May 12, 2013 10:45 pm**

Was it laid on a grit sand mix or a building sand mix hard to tell from the photos

Posted: **Sun May 12, 2013 11:03 pm**

nice TV
sadly the paving should have been laid on a full bed
and it hasnt
i wouldnt try to seal it
shame because the work there on the whole looks very good quality
but it is wrong
LLL

Posted: **Mon May 13, 2013 8:49 pm**

GB_Groundworks wrote:Was it laid on a grit sand mix or a building sand mix hard to tell from the photos

No idea?

Posted: **Mon May 13, 2013 8:50 pm**

lutonlagerlout wrote:nice TV
sadly the paving should have been laid on a full bed
and it hasnt
i wouldnt try to seal it
shame because the work there on the whole looks very good quality
but it is wrong
LLL

So what are my options, do I have any?

Posted: **Mon May 13, 2013 10:48 pm**

not really
suck it and see
their basic technique isnt bad,regarding levels etc
but the lack of full bed is unforgivable

they are unlikely to want to change it
LLL

Posted: **Mon May 13, 2013 10:52 pm**

>>>>So what are my options, do I have any?

already given you my opinion above - sadly the only solution is to take it up and relay it or to live with it

The Brew Cabin

Silver granite damp - What to do now?