Patio woes

  realist 16:00 PM 11 Jul 11

Have been let down by a "builder" who was supposed to lay a small patio. He laid it more or less ok but failed to point between the slabs properly, the mix he used looks to be too sandy. So I'll have to rake it out and re-do. What is the correct mortar to use for this job please? Hopefully there is a suitable readymix I can get? Would this Wickes' product do the job, if so is it best put in dry or wet? click here

  wiz-king 16:42 PM 11 Jul 11

Normally you only use fine sand between slabs or a very weak mortar (6 : 1) this allows for expansion or contraction with the weather.

  cycoze 18:21 PM 11 Jul 11

I used to use a dryish mix of silver sand (fine) and cement at approx 4 to 1, kept it dryish so as not to stain the slabs while pointing it up...

Damp down the slabs and gaps on hot days and leave until they look dry, helps to stop the slabs and cement base from drying the grout/pointing mortar out to quickly.

Use two trowels, one large one small, scrape/push it from the large trowel into the joints and chop it in with the small trowel, use a pointing tool to press it down hard, a bit of bent/rounded copper pipe or even a bit of wood rounded off will do if you dont want to buy one., I used to cut the ends off old metal bucket handles, worked a treat.

Do it in the shade if possible or early evening, keep people off it for a couple of days afterwards, cover it up if rain is likely.

If you have a look online there are plenty of Building and DIY sites which will have more detailed instructions and possibly videos.

  cycoze 18:26 PM 11 Jul 11

Having re-read your original post, I think I would be inclined to ask the builder to come back and re-point it if it has not been finished properly.

  Forum Editor 19:04 PM 11 Jul 11

This is the way to do the job - whether you do it yourself, or get your builder to do it:-

Buy sharp sand (not soft, bricklaying sand) and OPC (Ordinary Portland Cement). Buy the sand in bags from a builders Merchant - Travis Perkins, for instance, and not one of the DIY sheds.

Make a wooden pointing stick that is a reasonable fit into the slab joints (which should ideally be around 12mm wide)

Wait for a dry day - not a hot one. The perfect situation is a day that is dry with a forecast of some light rain at night.

Use a wheelbarrow, and tip a whole bag of sand into it. Do NOT add any water.

Now add a quarter of a standard bag of OPC, and mix thoroughly.

Make sure the surfaces of the slabs are dry.

Throw the sand/cement mixture over the patio, treating a couple of square metres at a time, and brush the mixture into the joints. Run your pointing stick along the joints, holding it at an angle, so you compress the mixture into the joint. Then do it again - add mixture and compress until the joint is completely filled. If the mixture starts to dry out - and it will - sprinkle a little water onto the barrow. You're aiming for a mix that is damp, but not remotely wet.

Treat the whole patio in this fashion until all your joints are nicely packed, Lightly brush all the excess mixture up, and pack up -the job's done.

If it doesn't drizzle within 24 hours you can cover the patio with a fine spray from a watering can, but it must be a fine spray.

The resulting pointing will be hard, and look very neat. Make sure you compress that mix well. It's a knack, but you'll soon get the idea.

  Aitchbee 19:20 PM 11 Jul 11

Hello realist - an empathetic (and similar) situation with no practical advice - appologies. My veranda is still waiting for corrective work " ..When we get a good spell (of weather)..", said the company manager.The initial improvements began in february. All of my potted plants are doing well round the back ...every cloud has a silver lining...methinks.

  amonra 19:34 PM 11 Jul 11

Most builders merchants sell a grouting gun which can be filled with a 6:1 sand/cement mix and just "squirted" into the joints between slabs. Finish off with a piece of 15mm pipe. A lot easier than trying to pack it in with trowels etc. Done it,got the T shirt, saves a LOT of time and effort.

  jellyhead 22:20 PM 11 Jul 11

A site full of useful info link text

  Forum Editor 23:54 PM 11 Jul 11


Grouting guns may be fine for some applications, but unfortunately they won't work with a sharp sand/cement mix, and that's what you should use for best results with paving slabs. No professional patio layer would dream of using a soft sand and cement mix, it doesn't look as good, and wont last as long.

  morddwyd 08:18 AM 12 Jul 11

Didn't realise 'til I saw this thread that pointing was necessary.

I laid mine, on ordinary building sand, about ten years ago, and apart from a dose of Pathclear here and there every six months or so I've had no problems.

  Quickbeam 08:27 AM 12 Jul 11

"Buy the sand in bags from a builders Merchant - Travis Perkins, for instance, and not one of the DIY sheds."

Be aware that the DIY sheds are probably a good bit cheaper and more suited to the occasional weekend building project.

B&Q & other shed prices are inclusive retail ticket prices. The builders merchants are business orientated and are plus 20% VAT on all the ticket prices and give varying trade discounts to each customer depending on their annual spend.


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