Filling in the gaps in a patio

[shaunaustin]

Hi all,

My patio was growing weeds in the gaps between the flags so i've scraped most of the soil and existing sand out. I went to a builders merchant and they advised I buy KILN DRY SAND for refilling the gaps.

My neighbour said I should also mix in cement with the sand so that it hardens. I checked this out online and there seems to be a difference of opinion on this, with some people saying it isn't necessary to add cement.

Im a novice at this kind of DIY so could anyone clarify this for me? The gaps are quite big (about an inch deep) and a centimeter wide.

Many thanks,

Shaun

 

[r896neo]

if it is block paving then kiln dried sand is used but for most types of flags a proper mortar joint is used. Sand and cement mixed dampish and then pressed in and struck with a jointer/trowel.

How wide are the gaps?

 

[shaunaustin]

Thanks for your reply.

The gaps are about 10 - 15 mil. It is flags rather than block paving.

Thanks

Shaun

 

[Nick98]

Shaun

I am suprised they recommended kiln dried sand - not the thing to use for gaps that are that wide!

A question though is are the flags bedded down solidly so they are firm? If so then you would be best actually point them in using mortar.

Just get some ordinary building sand and some cement and mix at something like 5 parts sand to 1 part cement (no water at this stage). If its only a small area you local DIY shed will sell mortar bags which is building sand with a small plastic bag of cement inside it. They are normally a couple of quid each, in which case just mix all the contents of the bag together.

You then add some water - but be very sparing - you are looking to end up with something called a 'dry mix' which has very little water in it, this makes it easier to point up and stops the cement staining the flagstones.

If you want to cheat/save time a bit you can trowel it out (providing it is a dry mix) and brush it into the cracks with a soft brush. Once brushed in you can get something like this:

http://www.screwfix.com/p/marshalltown-brick-jointer/22646

or you can make something similar using the end of a piece of copper pipe. If its not very much you can use a piece of dowel or broom handle but the wood will wear out quite quickly!

Use this tool to press the mortar into the joint and then finish the joint off by running the tool along the joint.

However this will only work if the slabs are firmly bedded and all loose pointing and weeks are removed and the gaps brushed (or hoovered) out.

Enjoy!

 

[youngroughcaster]

I would agree with Nick98. Kiln sand in big gaps is no use. use a semi dry mix of sand and cement and brush it into the gaps, and compact it down/finish it off with a piece of piping. Brush the slabs off properly after, to make sure you dont leave any cement mix on top of the slabs.

 

[shaunaustin]

I've got a bag of mortor in the garage. Could I just use that? The idea being that when it rains I will firm up.

What do you think?

 

[ImayKnow]

I've got a bag of mortor in the garage. Could I just use that? The idea being that when it rains I will firm up.

What do you think?

As long as it is still fresh. Slightly dampen it though until it just starts to bind together - it will still be quite dry at this point so don't overdo the water!

 

[shaunaustin]

I think it's been in the garage a couple of years. It's got a bit hard in places but would break up. Thanks for your help

 

[ImayKnow]

I think it's been in the garage a couple of years. It's got a bit hard in places but would break up. Thanks for your help

Bin it then mate. You will end up having to do the job again!

 

[shaunaustin]

Ok will do. I'll just buy a new bag of mortor. I'm very conscious of staining my stone flags with the mortor so was planning to use a measuring jug to pour it between the gaps and then wait for rain to supply the water needed to firm it up.

This was recommended to me but I think the person who said to do it thought I was using Kiln Dry sand, which is easy to pour. I'm not sure how well this would work with Mortor. Might be better to get a tool which I can use to press it between the flags??

I know I'm taking liberties now with the amount of questions but I'm just trying to not screw it up and ruin my flags.

Thanks

 

[ImayKnow]

You will find that pouring in the water tends to wash the cement down through the sand, giving you a weak mix and will require future repair sooner rather than later.

Mix your sand and cement then slowly add water bit by bit until the mix just tends to bind together. It will still look dry, but can be troweled into the joint without staining the stones.

It's a tedious job but worth doing properly.

If rain is forecast you will need to cover the area to prevent rain washing out the mortar / staining the stones. Likewise if it is hot and in the sun you need to cover it to stop the water evaporating before the mortar cures.

 

[deandiy61]

if you haven't already done the pointing...you might use a piece of hardboard to push the dryish mortar further in the joint then retrowel .

 

[mattress]

 

[shaunaustin]

Hi all,

Many thanks for your advice. I did the job a couple of weeks ago. Despite it taking an absolute age it turned out really well. Crucially, no straining on my nice stone flags! Now let's hope it lasts through the winter.

Thanks very much.

Shaun