Thread: how deep can i go with a type 1 aggregate subase

Originally Posted by billzgolf

have 6 inch of compacted type 1 aggregate down in preperation for a garage slab,have a run off of around 12 inches where it slopes front to back.is it ok to go ahead and level this with more hardcore in 6 inch layers before shuttering off and pouring the concrete.or just level with extra concrete.
will a 6 or 8 inch slab suffice for a single skin 100mm thick concrete block garage
<!--/Text--> 12 feet x18 feet x 7 feet high,any advice appreciated,esspecially on the best way to level up.

Whilst I have no idea on the spec of "type 1 aggregate", if it is crushed rock it will be fine to compact in layers as a subbase. I would do it in 4 inch layers though, unless you have a heavy vibrating roller or a good tamping foot compactor. Much cheaper and better than using concrete, as it won't impede the drainage too much. As to the slab, it should be borne on a footing, which will be of a depth to suit the subsoil you have. For example, a heavy clay soil requires a much heavier footing than a sandy subsoil as the clay shrinks and swells a great deal with changes in moisture, where the sand does not. Going that way would allow you to use a lighter 4" slab. You can get away with a very heavy "raft" slab and essentially no footing, but the additional cost of reinforcement and the extra concrete would make this an iffy proposition except in certain circumstances. If you do intend to go this way, you will need strong reinforcement in the top part of the slab to prevent the weight of the walls "breaking its back" and lesser reinforcement in the lower part of the slab to prevent any shrinkage of the subsoil from creating a hollow under that will also crack it over time. I would also put some additional thickening under it at the entrance. Having said all that, an 8 inch concrete slab is a big, strong bit of gear and it would probably do the job.

Originally Posted by billzgolf

have 6 inch of compacted type 1 aggregate down in preperation for a garage slab,have a run off of around 12 inches where it slopes front to back.is it ok to go ahead and level this with more hardcore in 6 inch layers before shuttering off and pouring the concrete.or just level with extra concrete.
will a 6 or 8 inch slab suffice for a single skin 100mm thick concrete block garage
12 feet x18 feet x 7 feet high,any advice appreciated,esspecially on the best way to level up.<!--/Text-->

thanks for that,ground is sand/clay with four inches of heavily compacted subsoil on top,i know most of the surrounding garage slabs have been laid with no subase and seem stable after up to 6 years,i wanted to go the extra bit by using half inch rebar around 300mm of the perimeter of the slab and mesh in the middle,perhaps pouring to 10" around the perimeter and 6 inch in the middle for added strengh.

Great forum this,
A bananalander telling a resident scotsman how to lay concrete.

Originally Posted by echnidna

Great forum this,
A bananalander telling a resident scotsman how to lay concrete.

How would he go fielding a question on cure rate and dryers?

Originally Posted by johnc

How would he go fielding a question on cure rate and dryers?

It all depends on how severe your tinea is.

just please dont start playing bagpipes...

one informative reply and the rest pathetic attempts at sarcasim,
these forums are for sharing information and not for would be comedians
to practice their crap routines the wife won't listen to!
so either contibute or keep it shut!

Originally Posted by billzgolf

one informative reply and the rest pathetic attempts at sarcasim,
these forums are for sharing information and not for would be comedians
to practice their crap routines the wife won't listen to!
so either contibute or keep it shut!

Mate, in all seriousness, this is a group of people who like to have a bit of fun and help out where they can. If you want people to keep helping (I'm glad you found my response informative), grow a thick skin and expect a fairly low s/n ratio. Let's face it, you're in scotland asking for advice from a group that is largely Australian: at least part of our genetic predisposition to take the came from Scotland!! I can assure you that abusing people for their "pathetic" humour won't get you too many willing respondents in future. Besides, I thought my attempt at humour was quite good!

Originally Posted by billzgolf

one informative reply and the rest pathetic attempts at sarcasim,
these forums are for sharing information and not for would be comedians
to practice their crap routines the wife won't listen to!
so either contibute or keep it shut!

A newey and already getting up us.
There is more info available here than one will ever require, or need:eek:

Hey!!
Don't go in the Kitchen if you can't stand the Heat.

Maybe I require a Hadrian's Firewall in the 'Poota



Where is the FINGER Icon..... Oh other Forum
http://forums.eurocca.net/index.php

your right its not the forum for me,will stick to the
uk tech forums for specific information,and your kidding yourself if that passes for humour over there,i can assure you it wouldn't crack a smile in this bonny land!
dame edna or billy connolly its a hard decision!!!!!!!!!!!!

Originally Posted by billzgolf

your right its not the forum for me,will stick to the
uk tech forums for specific information,and your kidding yourself if that passes for humour over there,i can assure you it wouldn't crack a smile in this bonny land!
dame edna or billy connolly its a hard decision!!!!!!!!!!!!

Quite right, I enjoy them both and for completely different reasons. Sorry you find it so difficult to crack a smile, I hope your garage goes well.

ok lads point taken on the chilling out!but then i'm building a garage when i should be at the golf or up the pub thanks to the other half,so i aint smiling AT ALL just now.
have decided to pull the hardcore back widen the plan
and dig a 600mm(w) x 350mm(d) trench footing reinforced with rebar,will just pour a seperate 4" floor a bit later and go with a double skin cavity 100mm dense block garage,more expensive more trouble but should give a solid garage.
does this sound about right on my hard clay soil or am i still off the mark here?

G'Day,Bill,
Glad to see you back here.

Our Aussie Humour might grow on you, Maybe not:confused:

I built a Garage 3 years ago on REACTIVE Black Soil [CLAY] Type 'H'
That is as bad as one can get here-abouts.

My Garage is 9M Wide X 7.5M Deep
It has 125mm Slab, with extra "Ribs" around the Perimeter,
also across the middle @ about 3.75M,
and at 3M intervals.
I also went up ONE size in Reinforcing Mesh, Deformed, NOT Smooth [Plain] Fabric.

The Slab is still intact with NO cracks.
Others in the area went cheaper and their slabs have cracks, some [ONE] severely.
ALSO, I kept the slab wetted for well over a Fortnight.

Hope this helps.

Bill,



On the size slab 4" would suffice but I would opt for 5" if you intend parking anything heavy on it such as a car. However as long as your footings are sound you are only spanning the slab over a 8' gap anyway.
I am not familiar with your soil ratings but the size of your footings at 24" x 12"+ certainly provide plenty of support for a single garage, around here this size would only end up with a 12" width and you might give some consideration to lightening the footing in exchange for lifting the slab. Certainly bar in the footings plus mesh for the slab is the way to go.

I would consider doing the lot in one pour footings and slab assuming you are getting a truck mix, you will get a stronger result overall as you avoid seperation at the join between slab and footings. However your dimensions are unlikely to cause trouble unless the sub base shifts over time. As I said your soil type and specs are lost on me.

Regards, John.