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Posted: Tue May 17, 2011 12:21 pm
by G_W
Hi,
I have recently laid an Indian Sandstone patio at my house and seem to have been confused over the correct laying of it!
I was originally planning on laying the flags on a wet bed of motar, 4:1 using building sand but after advise from a couple of people I laid the flags on a semi wet/dry 4:1 mix using buidling sand.
I havent yet pointed the flags but have noticed a couple of the flags have a very slight rock to them which wasnt there when I laid them. I am hoping that once I have pointed them that it will be all solid with no movement but at the back of my mind I have started to think I am going to have to lift them all and start again using sharp sand. I hope this is not the case as the patio looks fantastic and 95% of the flags are really solid.
Can anyone advise if I should just bite the bullet and start again or make good rocking flags, if so how??
Thanks
Greg
Posted: Tue May 17, 2011 8:19 pm
by London Stone Paving
Hi Greg
If it was me I would have used 4 parts sharp sand and 1 part cement but different people swear by different ratios. I personally dont think building sand has enough body for paving but If youv'e only got the odd loose slab then it sounds like you have done ok
Whatever mix you use a couple of rockers can happen to anybody, so no need to panic.
Carefully remove the rocking slabs and take out the mortar underneath in small sections. If you have got a grinder, use it to cut the mortar out and seperate it from any adjoining mortar. This may sound OTT but its better than dislodging any of the good slabs.
Once you have removed the old mortar just drop the slabs back in on a fresh mix
Posted: Tue May 17, 2011 9:24 pm
by dig dug dan
spot on advice there from london stone.
the number of times i have been back to a patio the day after i laid it, to find the customer has "found" loose slabs. the only way they could have done that is if they had walked on them, despite being told not to.
They are then surprised when you tell them the mortar does not stick to indian stone as well as it does with manufactured flags, and they think you are trying to fob them off.
such is life!
Posted: Tue May 17, 2011 9:41 pm
by lutonlagerlout
i find a mix of 4 parts grit sand (screeding sand) 1 part soft and 1 cement works well,with a dollop of SBR thrown in
soft sand is not really adequate for a patio although it may last a few years,
the time to look for rockers is when its pointed
LLL
Posted: Tue May 17, 2011 9:48 pm
by local patios and driveway
i must say ive not once had an issue with rocking stones but i always lay on a wet bed or a slurry on a semi dry bed. must be related? i always lay on a sharp bed
Posted: Tue May 17, 2011 9:56 pm
by lutonlagerlout
I always lay on a bed the consistency of bricklaying mortar and never have problems
LLL
Posted: Tue May 17, 2011 10:29 pm
by G_W
Thanks for all the advice. I will lift the rockers tomorrow and relay. I counted them tonight and there appears to be about 3 in 24m2.
When I was checking which ones were loose tonight I notices a few which although they have no movement they seem to sound hollow when you tap them with your finger compaired to others which just sound solid. Will this eventually mean they will become loose or will they be solid once I have pointed them.
Thanks
Greg
Posted: Tue May 17, 2011 10:36 pm
by cookiewales
i allways lay on semidry sharp sand 4to1 solid bed well tapped in sometimes with slurry if thin .ps bricklaying sand big no no 
wet mix lll uses is also good but not for the diy bods :;):
Posted: Wed May 18, 2011 6:47 am
by mickavalon
We use semi Dry 4:1 Sharp/cement only for thick Stone such as Yorkstone, and a wetter mix 3 sharp, 2 Building and cement for thinner paving, and a bit of SBR for anything that doesn't grab well (Slate etc). Never had any comebacks yet, but been and re-laid a couple recently were other companies have laid Indian Sandstone on Dry beds, told the client it was to allow natural moisture to be drawn up into the bed. Still wasn't set after 2 Years.
Posted: Wed May 18, 2011 8:55 am
by London Stone Paving
G_W wrote: When I was checking which ones were loose tonight I notices a few which although they have no movement they seem to sound hollow when you tap them with your finger compaired to others which just sound solid. Will this eventually mean they will become loose or will they be solid once I have pointed them.
Sounds like you were not thorough enough when spreading your mortar bed out and you have left a few cavities. They may not come loose immediately but long term they might. If it was me I would pull them up and re-lay them
Posted: Fri May 20, 2011 8:47 am
by jonnyboyentire
I tend to put a bit of soft in a gauge as I find it flows off the trowel better. Wet bed though.