Buttering/jointing - Advice for person new to patio laying

[angeldust1]

Hi,

I'm planning to lay approx 30 square meters of light grey Stowmarket imported sandstone using the methods described on this excellent website. The only flags I've layed before were for a shed base where they butted up against eachother.

I'm going to use a 10:1 sharp sand:cement bed. Was going to fill the gaps with one of the polymeric sand products, but from what I've read on this site, I've decided to have a go at jointing with a semi-dry mortar as descrided in the case study on the jointing page.

I'm slightly confused about the advice given for buttering and jointing:

If I'm using the semi-dry method, do I need to butter the flags together as I lay them, then top-up the filling when I join? Or can I simply lay the flags 'dry' and join later?

Also how long can I wait between laying the flags and doing the jointing. I reckon it will take me a good few days to lay the entire patio. Do I do the joining as I go along or will it wait until the whole thing is finished?

Thanks in advance fior any help.

Paul.

[Tony McC]

You'll get best results from buttering as you go along, and then pointing-up the joints at the end of each shift, while there's still a bit of 'life' in the butter mortar. It's not a good idea to point as soon as the flags are laid, as you may need to adjust the joints as more flags are laid because of the 'accommodation' problem that occurs with all of the modular flag ranges. Without getting bogged down in too much detail, if you lay two 300mm wide flags, you end up with a section of paving that's wider than a single 600mm wide flag - 300 + 12mm joint + 300 = 612mm. Consequently, several joints may have to be widened/narrowed to 'balance' the paving once it's laid. It's simply not possible to lay all of the paving with a consistent joint width.

There is an argument to be made for leaving all of the pointing until the end of the job, as that will ensure consistency of mortar colour. If you point-up at the end of each shift (by which I mean lunchtime and finishing time in a full 8 hours day), there's a risk that there'll be some variation in shade of the mortar. However, while this may be noticeable for the first month or so, once the joints start to weather, any slight colour variation will become much less apparent.

If you were planning on laying all of this over a weekend, then I would be tempted to leave the pointing until the Sunday evening, but if you're thinking this could be a couple or three weeks of a project, then pointing at the end of each shift, with particular attention being given to consistennt mortar prep, would probably be a better idea.

It's also important to factor-in the weather. You can't/shouldn't point when the flags are damp or when there's rain expected in the next 6-8 hours.