Concrete Shuttering Query

[worldwidewebs]

We were going to lay stone paving on the largish patio and the paths around the side and front of the house so we put down a base of compacted crushed stone - but it has now been decided that we're having porcelain tiles instead, which means I now need to have a concrete base to lay them on. And this is where I'm not sure how to approach it.

 

The stone is reasonably level but not quite and I'll need a slab which will be between 75 and 110mm thick. What would be the best way of tackling the shuttering? I've been looking at hiring steel road form as it looks like this could help make levelling easier but is timber just as good/easier? I've never done this before please feel free to advise and guide a novice!

 

 

[ToughButterCup]

Have I got this right? You want to lay tiles on a concrete base. The 'sub-base' is level-ish.

Construct your wooden  shuttering (sometimes called formwork) at the level you require. Pour the concrete. 

 

Here are too many YT videos for you to review on a wet Monday evening

[Barney12]

I'm no expert but I used roadform once and I found it heavy and difficult to adjust accurately. The love of timber is its light and reasonably easy to adjust. Screws are your friend so you adjust levels as you go. 

The one exception is ref ground conditions. If they are really hard (and you can't drive a wooden stake into our ground) then timber becomes more challenging.

 

there's a great write up of the two types here a long with loads of other helpful info on concrete:

 

http://pavingexpert.com/formwk01.htm

 

[worldwidewebs]

9 minutes ago, recoveringacademic said:

Have I got this right? You want to lay tiles on a concrete base. The 'sub-base' is level-ish.

Construct your wooden  shuttering (sometimes called formwork) at the level you require. Pour the concrete. 

 

Yes, that's right. Whereas with stone we would just lay sand and then a bed of mortar the tiles need something more substantial. I initially didn't want to go down this route but deep down I know it'll look good and I've come this far...

 

When you put the timber down, how do you best go about filling in any gaps under it in the cases where the crushed stone isn't level? Or don't you...

Edited August 14, 2017 by worldwidewebs

[worldwidewebs]

9 minutes ago, Barney12 said:

I'm no expert but I used roadform once and I found it heavy and difficult to adjust accurately. The love of timber is its light and reasonably easy to adjust. Screws are your friend so you adjust levels as you go. 

The one exception is ref ground conditions. If they are really hard (and you can't drive a wooden stake into our ground) then timber becomes more challenging.

Thanks - that's just the sort of insight I was looking for.

 

I'm not sure how easy it'll be to drive wooden stakes into crushed stone though  

[Barney12]

4 minutes ago, worldwidewebs said:

I'm not sure how easy it'll be to drive wooden stakes into crushed stone though  

 

Not easy but not impossible as long as the stones aren't too big. Is it just MOT1? It's the ground conditions below that will slow you down if it's full of large stones/rocks. Just whack a metal bar down first and that will loosen up the stones for your stake. A short length of rebar or a 600mm foundation pin is ideal for the job. 

 

Edit: mind your fingers when whacking the pin/bar. Putting your finger between the lump hammer and the pin REALLY hurts. Ask me how I know. Had to go o the local vet and get him to sew the top of my finger back.  (Yes, I did mean vet. So much closer and quicker than A&E )

Edited August 14, 2017 by Barney12

[worldwidewebs]

Yes, just compacted MOT1 on top of soil

 

What did you find was the best timber to use?

[Barney12]

11 minutes ago, worldwidewebs said:

Yes, just compacted MOT1 on top of soil

 

What did you find was the best timber to use?

 

Any treated timber is fine. I've used 6x1 for shuttering but you can also rip down 18mm OSB sheets which will work out cheaper. 

If you've got a chop saw then roll your own stakes using 50x50mm treated timber cut to a good deep point.