Concrete float foundations, how thick?

this is the stuff i mean, usually quite cheap at jewson etc

when i did a base for a sectional garage i used this stuff!
http://www.ebay.co.uk/itm/XT-Fibres-Concrete-Screed-900gx12-18mm-fibers-/120813860255?_trksid=p3284.m263&_trkparms=algo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D21%26pmod%3D120855682514%26ps%3D54#ht_1411wt_1139

 

A raft foundation spec'd by an engineer will have mesh top (just under the surface) and bottom. However I can tell you everything a structural engineer does these days is well over spec'd. I have my own building company and the only thing ill say is, if your going to buy the raw materials and mix it yourself, find a merchants that sells it loose as you will most certainly get it cheaper. If your mates' a builder he should know where to go. And finally ALWAYS haggle, merchants make a lot of money through mark up and they are like any other business, if they don't want to loose the business they'll almost always crumble in the end.

 

cool, but the fibres work out much cheaper!
i usually get my sand from the local quarry, the hardest thing for you would be haulage, but your mates prices are spot on!

 

Mate has a 3.5ton trailer and a van i can borrow so transport isn't a problem. He's got wacker plate and a mixer too.
I restored his T25 camper a few years back so he reckons he owes me.

 

Dragging this kicking and screaming back to the top.

Can i get away with using 18mm OSB board cut into strips for the concrete formwork? I reckon an 8ft x 4ft sheet cut into 6" strips would do all the formwork if it did.

 

Just make sure you brace it well buddy if not it will bow out and break. Lots of 2" stakes at regular intervals

 

Would 2" stakes at 18" intervals do or will they have to be closer?

 

That is close enough.

 

Cool. Its gonna get (more) expensive otherwise.

 

so you got the easy part done by someone else

 

Garage i've been offered is 19.5ft x 9.5ft so it should fit on a 20 x 10ft float OK and give a bit of space to work around a vehicle inside.

 

Sounds good buddy.
A tip- chamfer the edges away from the garage if that makes sense. It'll stop water seeping in underneath. Just run a plaster float round the edge when it's gone off a little so it slopes a tiny bit

 

as ZED said, plus if you want to be real safe just use one layer of a structural mesh rather than A193, something like B283 or B385 as thats all a structural engineer would use. In truth you should be fine with A193 or A142 with a light weight sectional garage as long as you have some form of reinforcement.

 

Gonna use a single layer of A142 just below (maybe 2") the concrete surface as thats all thats available locally. Don't want to spend £40 on delivery.

There used to be a huge concrete storage shed down the road from me which was demolished a few years ago and theres now just this massive pile of hardcore. Unfortunately i can't find out who owns it. None of the house owners nearby i talked to seemed to know and its all security fenced off with the sign painted over with graffiti.

 

Check the garage you've been offered for height, precast garage's are often quite low

 

Panels are 6ft 6" high. Door is up and over type so 4-6" lower. Not high enough for my westy but my bug will fit OK.

 

I was working in a precast garage last week where the fella wanted extra height so he strapped 9x2 treated timber to the top of the concrete panels then put the roof on that, You could also do the reverse with the door, eg screw what ever you add to the top of the concrete penels to the bottom of the door

 

Haha great minds, I was thinking chuck it on a brick plinth and add to the bottom of the door, or change the door.....now where did I leave my horse...

 

You should be aiming for something like on the photo, a bit overkill but if you end up with something similar you wont go far wrong, depends on you surface ground, its quite a big area so unless the conc wagon can poor straight into the base you need bodies to barrow it in, if you do it when its hot it'll go off quicker, ask driver to wet it up if necessary, he'll now how wet you'll want it on the day, likes been mentioned chamfer the edge away from garage, if you want a non-slip type of finish (also gets rid of surface water after you float up), get a yard brush and drag it with the back of it (like a paint brush), towards you, leaves a nice finish and gets rid of trowel marks!,