My first patio - Clarification needed

[novicebob]

Firstly I'd just like to compliment you on a very good and informative webite.

This is my first attempt at anything like this so I apologise in advance if my questions appear basic.

I am laying a small patio (4m by 3.5m) using 450 x 450 x 32mm slabs. I have done the excavation so I am now at the exciting part and would like some clarification if possible.

1. I am going to put down 10:1 sharp sand and cement as suggested but in a couple of places on the website you refer to this as semi dry. Are you saying I have to add water to the 10:1 mix? If so how much?

2. Once I have put the sand\cement down I will then compact it with a hired compactor. Once I have done that do I add another layer or do I then screed the compacted layer?

3. How long have I got after laying the sand to get the slabs down. Not being an expert I'm worried that I will put all the sand down but not have time in the same day to screed and lay all the slabs.

Thanks in advance for your help.

[Tony McC]

1 - no added water. Rely on the natural water content of the grit sand. It's semi-dry because there's no added water. A dry mix relies on bone dry sand.

2 - you could do, but it's not the best way, IMO. I prefer the pre-compaction method, whereas what you describe is known as partial pre-compaction. Read the Screeding page for more info.

3 - Using a 10:1 semi-dry mix at this time of year should give you 4-6 hours of working time.

[novicebob]

Thanks you for your reply Tony.

A bit of logistical advice needed. The pation I am building is at the bottom of a 50ft garden and the only access to the garden is down a samll alley from the front of the house.

On Friday I am getting delivered 1 tonne of sand (no idea how much that is!!) and 5 bags of cement. I have a 3 cubic ft wheel barrow in which to transport the sand down the alley and then down to the patio area. I wonder if you could use your vast experience and estimate answers to the following questions.

1. How many trips will it take to transport the sand?
2. How is the best way to produce the 10:1 sand\cement mix i.e 10 spades of sand into the barrow followed by 1 spade of cement and mix around with the spade and then dump in the excavated hole or is it possible to dump the sand into the hole and mix the cement in there?
3. Is it going to rain this weekend!!!!

Thanks in advance for your help again

[Tony McC]

A typical builder's barrow carries around 0.05 cubic metres, so there are 20 barrowloads to the cube, or roughly 10 to the tonne (100kg or 4 pre-pack bags). However, while many groundworkers and contractors would have no difficulty pushing a 100kg barrow, it can be more of a challenge for those more used to pushing a mouse, and they might only manage 50kg at a time.

Mixing 10:1 - Add 5 of sand, then 1 of cement and then 5 more sand. Mix on the ground, if possible, as it's much easier than trying to mix in a barrow.

Rain - not raining here at the moment. I might even go out and plant up me winter dangly baskets for the front door, when I've finished this.