floor screed - couple of questions

Hello all,

I am planning on doing some screeding in my new kitchen extension this weekend, and have a couple of questions.

1 - dont scream at me..... but I will be getting a couple of tonnes of sharp sand delivered, can I mix in about a half tonne of soft sand that I have left over from the brickwork?

2 - mix, I have been told somewhere between 3:1 and 4:1 sand/cement, could someone confirm which is better for my purpose

3 - depth, my kitchen was originally a smaller bathroom which I built around and then knocked down.... leaving the floor of the bathroom intact in the new 'kitchen' floor..... should I rip this up (its quite well done and solid with stone tiles - not nice ones) or can I screed over the top?..... this would mean that it is slightly thinner over this area.

Thanks for your help!

1 - dont scream at me..... but I will be getting a couple of tonnes of sharp sand delivered, can I mix in about a half tonne of soft sand that I have left over from the brickwork?

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No. Although it may do no harm, it will effect the strength of the product and will effect the way you rub up and trowel the finished product.

2 - mix, I have been told somewhere between 3:1 and 4:1 sand/cement, could someone confirm which is better for my purpose

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4:1 will be strong enough but don't go any weaker.

3 - depth, my kitchen was originally a smaller bathroom which I built around and then knocked down.... leaving the floor of the bathroom intact in the new 'kitchen' floor..... should I rip this up (its quite well done and solid with stone tiles - not nice ones) or can I screed over the top?..... this would mean that it is slightly thinner over this area.

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How much thinner?

Thanks Noseall.

1 - yup, I just stuck with the sharp to be careful!

2 - yup, followed that

3 - in some cases it actually ended up being just under 100mm because of some uneveness in how the base was put in, in most places is is about 65-70mm
In the place where the kitchen tiles are still in place, the depth is still about 40-50mm so hopefully that will be ok?

NB I am doing this in 3 stages due to the room being used as a temporary kitchen!

40-50mm will be ok as it is bonded to thicker areas of screed.