Patio grouting

pbull69

I have just laid a 30sq metre patio on a bed of sand which rests on compacted crushed rock. I dont really want to use sand for the grouting. What bout using dry concrete and wet afterwards??? Is cracking a problem??

De_man

hi

Putting the slabs down on plain sand can lead to a few probs later
but you should get away with it provided its only for light use and the sand
is very well compacted, and you've proper edging in place.

What i did here was, mixed up a dry mix of sand & cement 5:1 then using
2X1's batons as levels screeded the mix ensuring the falls from the house.

Put the slabs then into position, in a RANDOM pattern, nothing worse than putting the slabs down one after another, but for your area you'll
need the following sizes 24 X 18, 18 X 18 and 12 X 18s to get the proper effect.

Regarding the grouting, under no circumstances put in dry concrete
and then wet afterwards you'll destroy the edges of the slabs and
the place will be stained by concrete:eek:

Two ways to grout.


1.
Mix up Grout, and do your best to fill in the gaps, i used a cornflake packet and back of trowel, leave to dry for a few hours, then by using the handle of a trowel or the kitchen brush run the handle along the gaps, don't be tempted to brush the slabs at this stage, leave to dry for another hour or so, then you can brush off the excess, should any slabs get stained use a sponge


2. The easiest way to do the grouting is to wet the gaps in the patio thoroughly, whilst it's drying off mix up your grout (dry mix), you'll notice the slabs are drying off but in between the slabs is still wet.

now apply the dry grout mix as above, the dry mix shall soak up the water
thats in the gaps between the slabs, leave to dry for a few hours and complete as above.

what colour are the patio slabs? if they're grey, red or multicolour
i recommend you get some dye to match the slabs, it does a much
better job, you'll get the dye for about 5euro from your patio slab dealer

Finish the job by edging the patio in matching bricks that suits patio or house

oh yeah make sure the weather is dry


and to answer your question is cracking a problem?, it might be, imho it's not
a great idea to lay a patio on plain sand, the slabs do tend to rock and roll
after a while it's much better to set the slabs in a weak concrete mix.

hope this helps


a pint of plain is yer only man

Doolittle51

Dont want to hijack the thread, but:

How deep should you make the screed mix? I need to build a small patio soon (about 5 sq Metres). I intend to dig up the sods in the area and lay screed on top of the muck (no hardcore).

Any advice appreciated.

Jambo

check Paving Expert - should have all you need there

Sonnenblumen

Would agree with previous posts sand base not ideal for patio, a better solution is a dry mix of compacted coarse sand/cement (5:1) base min 25mm
(1") on compacted hardcore base minimum 100mm (4").

The best base however for patios but takes a little more skill and effort is to lay slabs on wet mix of sand/cement (same proportions apply). If done properly this method prevents any slab cracking and/or movement.

Tip: to reduce damp penetration which can cause dark staining on concrete, place a layer/sheet of builders PVC on compacted soil before putting in hardcore.

For grouting - offer 2 options:

(1) dry mix (3:1) sand/cement brushed into joints and compacted well with a straight edge to same level/slighly below level of slab, afterward sprinkle water over joints but very little required. A watering can with a fine rose is ideal. Grouting will set rock hard.

(2) very wet mix (soup consistency) of sand/cement (2:1) mixed well with plenty of water which can be poured carefully into the joints using a measuring jug or any container with a triangular spout. If stuck a plastic 2L Coke bottle with neck removed can also be used. Any spillage onto slabs must be carefully washed off immediately to prevent staining.

This also gives a very good even and more consistent finish to (1) and also sets rock hard.

De_man

must agree with everyone else, i forgot to mention yesterday, it's becoming
very common to put patio slabs on top of the existing pathways of the
house, then extending the patio outwards.

If you are doing this ensure that you don't go above
the DPC of the house and ensure you've got your 150mm from the DPC otherwise this could lead to dampness, also ensure
the slope (very small) is away from the house and not towards it.


regarding the dye for the grout, you'll only need a small trowel full
when doing a mix, it takes the bare concrete look from the grout

if you're going for the "random" pattern PM me and i'll work out the ratio of
patio slabs you'll need



a pint of plain is yer only man

squire1

De_man wrote:

hi

Putting the slabs down on plain sand can lead to a few probs later

By plain sand, do you mean builders sand or sharp sand/grit sand. Using grit sand is fine I presume? Thats the way I've done it a couple of times (on top of a well compacted sub base of clause 804) and I've had no problems. I'm no expert so I was just wondering what problems you envisage with grit sand if that is what you mean.

De_man

squire1 wrote:

By plain sand, do you mean builders sand or sharp sand/grit sand. Using grit sand is fine I presume? Thats the way I've done it a couple of times (on top of a well compacted sub base of clause 804) and I've had no problems. I'm no expert so I was just wondering what problems you envisage with grit sand if that is what you mean.

hi squire1

apologies for delay in replying, been really busy of late, i've found that occassionally patio slabs bases are not exactly square/flush and tend to loosen over time, i normally use a weak sand/cement mix to set them in
the patio here has been put down 5years ago and its still perfect

Doolittle51,
if its your first time putting down a patio and to ensure you get the levels
right etc etc, why not make up a timber frame using a few lengths of 4 X 1"
it's pretty cheap, it'll make the job so much easier.

i used this method when i the levels in my back garden (existing)
were different (and i wanted to take the easy way out:D )

1. remove the top sod & soil to the required area- say 4inches

2. make up the timber frame that'll surround your patio

3. Insert timber frame into ground where you removed the sod (have the top of the frame approx 1" below the top of the surrounding sods/grass, if you
want your patio flush with the garden.

check timber frame levels with spirit level, insert rocks if needed to raise or lower frame or change the slope, if you don't have a level use a bottle of water and use the bubble as your guide, it works

4. make up weak sand/cement mix (i used 5:1), put mortar into the frame
filling the frame, then using spare timber screed the get it perfectly
level with top of frame

5. leave mortar "go off" for a bit/harden (don't leave it go off fully let it set about half an hour or so, otherwise the slabs may sink in the mortar :eek:

Drop slabs onto top of timber frame they'll stay in place - leave timber frame in situ for a few days then remove,


6. grout as described by the others above when the weather is dry


Hope this helps


a pint of plain is yer only man

gregrockwell

Hi guys,

spent all day yesterday grouting slabs in my garden, used 3 parts sand 1 part cement, might have been slightly generous with the sand but think not too far off, mixed it dry and poured in and brushed as i went along. the mix this morning is very sandy lookin and not as hard as i thought it would be in the joints, was a lot of rain last night,,, how long does it take to harden and go white or have i fekd it up!!!!!???
any responce appreciated

Thanks

phil mccrackin

cracking can be a real problem, ive recently had the area around my velux window plastered ,its a real poor job i think they one coated it and now theres cracks in it around the window, as well as big hole, big enough for a mouse to get in and ppesky draughts to blow in.

if your doing an area of flaging with a solid bed under the flags mix the sand and cement at 4. 1 but just add a drop of marmalade to it, it acts as a great binder.

sheff the ref

Around that time in 2011 I did the same job, probably went slightly heavier on the cement. I was replacing joints that had perished over about 20 years. The drymix never hardened properly, and the stuff that did harden didnt stick to the sides of the slabs properly and weeds grew up through it. I have spent the last couple of days with a kango breaking the stuff that was hardened loose.

I think at this stage there are no shortcuts apart from mixing wet mix and carefully applying and packing it into the joints.

gregrockwell wrote: »

Hi guys,

spent all day yesterday grouting slabs in my garden, used 3 parts sand 1 part cement, might have been slightly generous with the sand but think not too far off, mixed it dry and poured in and brushed as i went along. the mix this morning is very sandy lookin and not as hard as i thought it would be in the joints, was a lot of rain last night,,, how long does it take to harden and go white or have i fekd it up!!!!!???
any responce appreciated

Thanks

WilyCoyote

Why not use hydrolic cement?

sheff the ref

Sets too quickly for working with. Grouting between patio slabs is a tedious and time consuming job

WilyCoyote wrote: »

Why not use hydrolic cement?

WilyCoyote

Am going to grout mine in a week or so. Have got to use hydraulic cement because of climate. If water gets underneath and almost three months of sub zero temps. Including a month of -15C to -20C day and night.
Will post a pic when done.