Why do they rock?

Patio flagstones (slabs), concrete flags, stone flags including yorkstone and imported flagstones.
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googlebot
Posts: 2
Joined: Mon Apr 14, 2003 10:54 pm

Post: # 1626Post googlebot

Firstly can I just say that this is possibly the best website I have ever found relating to DIY. Everything is covered and its a delight to use I could not have laid my patio without it.

I have just finished laying my new patio using Bradstone Wetherdale flags. For the biggest part everything is fine, the new drain I put in works a treat and there is no ponding or puddles and if I do say so myself it looks the mutts nutts. :-)

However, on one or two slabs there is a slight rocking that is barely noticable, but still enough to crack the pointing in the joints. I laid them on a 10 to 1 mix of sharp sand and cement and there was no rocking when laid and I am pretty sure I hit them hard enough with me rubber hammer because at one point the head flew off like one of those power balls. ;-)

So,

Number 1, are these slabs any good? (I hope so at nearly 7 quid for a 2 by 2, perhaps I should have asked before laying them).

Number 2, why are they rocking now and not before.

Number 3, am I going to have to get them up and re-lay the rockers, or is there a tip for fixing it without lifting it.

Again many thanks for the great website and any replies I might have.

68-1093879161

Post: # 1627Post 68-1093879161

Hell.....that's impressive....a googlebot that can lay a patio and type a question on a forum! I'm speechless ;-)

84-1093879891

Post: # 1630Post 84-1093879891

Hi Googlebot,

it seems strange speaking to a "spider", but there's a first for everything, I s'pose! ;)

There's nowt wrong with the Bradstone Old Town flags, structurally speaking - they leave a lot to be desired in terms of colouring and price, but that's another discussion. They are no more prone to rocking than any other flag that's available. Rocking is a result of poorly compacted bedding rather than anything inherent in the flags themselves (most of the time!)

You wonder why they "suddenly" seem to have started rocking. The most likely explanation is that they were probably rocking very slightly before you pointed the joints, but, because the joints were empty, the very small degree of movement was much less noticeable, and it's only because the pointing mortar itself is now cracking that you're suddenly aware of the problem.

So: how to fix. Well, sometimes they can be held firm by raking out all of the old mortar and re-pointing with a strong (4:1 or Class II) mortar, but, for those exhibiting more of a wobble, then a favourite trick of mine is to make a wet mortar slurry (see Wet Grouting) and pour that into the emptied joint, then straddle the flag and shift your weight about, causing the flag to wobble, so that it draws in the mortar slurry to fill any voids or slack spots beneath it. Once the slurry has 'set', the flag should be 100% solid.

You may find that one or two awkward sods absolutely refuse to co-operate and continue to rock despite your best efforts, and then there is no alternative but to lift them and re-bed them. Scrape out 25mm or so of the original bedding and replace it with fresh, damp (NOT wet, just damp) 6:1 mortar, then re-lay the flag and tap down to level with your clonker. Point the joint immediately, and keep it free from any traffic (that includes pedestrians!) for at least 24 hours.

Good luck!

googlebot
Posts: 2
Joined: Mon Apr 14, 2003 10:54 pm

Post: # 1635Post googlebot

Many thanks for the info Tony, will try the wet grout trick. Many thanks for your prompt reply and you is still got the best website in the UK.

Ps Am I missing something about my user name or what? Spider, a googlebot that can lay a patio, what in the hell is a googlebot then, because now I feel really stupid. ;-)

84-1093879891

Post: # 1637Post 84-1093879891

Googlebot is a 'spider', ie, a special program that scuttles across the web reading web sites (web - spider - geddit??) and creating an index for the Google search engine, so that it knows where to send you when you want specific information.

Now you know! :)

68-1093879161

Post: # 1664Post 68-1093879161

If you have administrator/super-moderator priviliges on vbulletin forums you can actually see the huge amount of googlebot crawlers going through the boards on the "Who's online' section.

Isn't the internet wonderful? Information at your fingertips.....this great site is one such example.

84-1093879891

Post: # 1670Post 84-1093879891

As I understand it, that can't be done with this version of Ikonboard because it uses a flat file database that has to be called from within the program and cannot be 'interrogated' by external 'bots. That was part of the reason for using an older version (2.19) of Ikonboard rather than the 'bell-and-whistles' version 3.x. However, traffic levels on this site, and particularly this forum, are now so heavy that I may have to move to an intergral system for next year. Any recommendations?

68-1093879161

Post: # 1673Post 68-1093879161

I can't recommend myself but I know a man who can....I'll ask ;-)

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