Please help me understand the layers - Question for newbie

[yanskii]

Hi
I am laying a patio this weekend with standard slabs of 45mm x 45mm x (I think) 35mm.

I have bought all my materials as follows:

850kg of Sub Base
850kg of Sharp Sand
10 bags of bricklayers mortar (may be a bit much?)

The sub base I understand.

However I am then confused why I have both Sharp Sand AND Bricklayers Mortar. The Bricklayers Mortar is a bag which contains another bag of cement within it, and also sand. The two are mixed together and they provide a ratio of around 1:5 I think.

On this, and all the other sites I have looked at, the info is that the layers go from Sub Base at the bottom, and then the bedding layer being the mix of mortar and sand. The paving slabs are then bedded on this. So why did I need Sharp Sand?

Wickes told me to lay the sub base, then lay the Sharp Sand, and than use the bricklayers mortar (spotting technique) on the slabs to bed them.

Thanks for any advice.

[steve r]

How about reading how to bed slabs.
http://www.pavingexpert.com/layflag1.htm

[yanskii]

I have and this is why I am confused.

The diagram shows sub base, bed (ie sand and mortar mix) and then flag. ie Three layers only.

My confusion is that the materials I have bought from Wickes and their advice suggests that I would have sub base, bed (ie the sharp sand alone), the mortar / sand mix and then the slabs.

Why dont I just use sub base, mortar / sand mix and then the slabs.

Sorry if I am struggling with the obvious here but I have never done anything like this in my life!

[Suggers]

Sharp sand / cement - bed.
Soft sand / cement (mortar) - pointing.

[Rich H]

You should add cement to the sharp sand to make your life easier - if not you will need to screed it perfectly in order to get the slabs laid evenly. Follow steve r's link above for individual bedding.

The packaged mortar for pointing is a waste of money really when you can buy building sand and cement (which is all that is in the bag of 'mortar') seperately so much cheaper. That's the morons at Wickes for you, I suppose.

If you only have a 'tonne' bag of sharp I presume you have 10m2 or less to lay? In which case 10 bags of mortar is way too much. Take it back and swap it for 1 bag of cement and 4 bags of building sand, you'll still have a bit left over but better too much than too little.

[yanskii]

Thanks for you help Rich H.

I think I will end up taking most of the bags of Bricklaying Mortar back now to be honest but I will wait and see how it goes.

I have 6m sq to lay and I have just been back and bought 4 25kg backs of Blue Circle Mastercrete Cement which I intend to mix with the Sharp Sand at 1:10. I expect I will have plenty of both SS and cement left.

Could you just confirm then, if I use the individual bedding method I do not have to 'Whaker Plate' the Sharp Sand / Cement bed? The paragraph suggests I just flatten it with a spade or trowel, leaving the top loose so the flag will bed in to it?

Or do I 'Whacker Plate' the Sharp Sand / Cement and then loosen the top or add a small loose amount for the slab to bed in?


Again, thanks for your help.

[ambient]

if you are adding cement to sharp sand add a bit of water so its wet (as in sticky not like pee)pat it down with trowel or back of spade put flag on and tap it down on to mix to level required

[Rich H]

The only thing that needs to be compacted with the plate is the sub-base. As for making the bedding course wet, I wouldn't! Moist is a better description - enough so that when you squeeze a handful it stays together.

If you follow the description in 'individual bedding' you'll be right as rain. Even if you're novice you'll get 6m down in a morning.