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Posted: Thu May 29, 2008 7:50 pm
by sako
Hello.
I have a concrete base to put in for a shed but it could be used for a dog kennel at a later stage.It is going on land which used to be part of a railway line so it is a solid base for it.
The dimensions will be 3.6m wide x 3.0 deep but over the 3.0m run the garden slopes 300mm so i would like some advise on how best to do this.
I was going to step the footings and lay 100mm thick concrete blocks flat all the way round 3 high and then back fill to within 100mm from the top of the blocks then fill with 100mm of concrete.
The problem is allowing for fall so the rain runs off,i wouldn't be so bothered if i didn,t intend using for dog kennel but i might,so how do i get round this?would i be better casting the slab over the blocks?then i could run a tapered board with the correct run off alongside the 3.0m run of blocks.Your expert opinions much appreciated. cheers
sean.
Posted: Fri May 30, 2008 6:09 am
by seanandruby
As it is on an old railway line the sub base should be quite deep. Cant you level that out so that you have a uniform laying base. then shutter the edge allowing your fall, then screed and tamp the concrete using the shutter. I would advise against concreting over the top of concrete blocks. Use them to face it up and pour concrete to level. good luck.
Posted: Fri May 30, 2008 7:48 am
by sako
Hi.
I can't really dig it out as i think the fall is too deep to do that (300mm) also i would be able to see 200 mm of backfill down the side under concrete when shuttering was removed..At the start of the 3.0m run i want the concrete to be around 100mm above ground.If i do it the concrete blocks way could i instead of laying blocks flat,lay them normal way up and cut each block creating the fall or is this too much work?
sean.
Posted: Sat May 31, 2008 1:56 am
by matt h
just shutter area and makeconcrete pad. fall will match shutter and easier to sort out. cheaper too;)
Posted: Sat May 31, 2008 9:32 am
by sako
Hi.Thanks for replies.
If i shutter it i would be able to see hardcore underneath concrete because the fall is 300mm and i only intend pouring a 100mm thick concrete slab and i want the finished height of concrete roughly 100mm above ground so how do i get round this? could i make it thicker round edges so then i would just see all concrete down edges when shuttering is removed?
I know shuttering would be easier it,s just i dont want to have to make up 300mm with concrete.
thanks sean.
Posted: Sat May 31, 2008 7:26 pm
by seanandruby
Add more hard core/type 1 to bring the levels up and batter back ( slope) the edges about 300 to 500 wide. When you strike the shutter you will have a concrete face to it. You could cast the slab with a 100/200 toe all round to carry some face bricks etc: dont forget the visquin :;):
Posted: Sat May 31, 2008 10:16 pm
by sako
Hi sean.
Thanks for advise.I know what you mean about sloping hardcore so then round edges the concrete will be thicker and faced up nice but i am not sure about casting slab with a toe,is this as well as what you have suggested or instead of? Please could you explain what you mean by toe for facing bricks.Thankyou.
sean.
Posted: Sun Jun 01, 2008 7:50 am
by seanandruby
have to wait for wife to put a drawing on for you. You "hang" a shutter around the base but raise it up so that you have a gap beneath it about 100/150 ml. Outside that shutter you put another shutter about 200ml away so that the top of it is level with the bottom of your first shutter. when you pour the concrete it fills up the top slab and runs under the first shutter and fills that up to your second shutter. basically you are creating a step. when you strike it you have a toe to lay your face course on. Dont have to high a slump of concrete or it will keep running out the bottom. as you level off the concrete run a trowel along the bottom of the top shutter for ease of striking. hope this is clear enough, good luck.
Posted: Sun Jun 01, 2008 6:01 pm
by sako
Hi Sean.
Yeah if you can post a pic that would be superb,but i think i know what you mean anyway.So basically the toe for the facing bricks follows the fall of the concrete so you just lay bricks on this without cutting the fall on the bricks themselves so brick joints would be sloping? or do you have the toe level and build brickwork say a few courses above concrete surface?Cheers your help is much appreciated.
sean.
Posted: Sun Jun 01, 2008 8:35 pm
by seanandruby
sako wrote:Hello.
I have a concrete base to put in for a shed but it could be used for a dog kennel at a later stage.It is going on land which used to be part of a railway line so it is a solid base for it.
The dimensions will be 3.6m wide x 3.0 deep but over the 3.6m run the garden slopes 300mm so i would like some advise on how best to do this.
I was going to step the footings and lay 100mm thick concrete blocks flat all the way round 3 high and then back fill to within 100mm from the top of the blocks then fill with 100mm of concrete.
The problem is allowing for fall so the rain runs off,i wouldn't be so bothered if i didn,t intend using for dog kennel but i might,so how do i get round this?would i be better casting the slab over the blocks?then i could run a tapered board with the correct run off alongside the 3.6m run of blocks.Your expert opinions much appreciated. cheers
sean.
I am a bit confused with the dimensions. Is it 3.0 deep, or 300? you cant lay bricks sloping you will have to make your footings level. You will need to step them if necessary. can you post a pic, or two to make it clearer? erecting a one sided shutter is risky as it can raise up and "blow" with the upward force of the concrete.
Posted: Sun Jun 01, 2008 8:48 pm
by sako
Hi Sean.
The area of the concrete pad will be 3.6m x 3.0m and along this 3.0m run i will slope the concrete pad to allow water to drain from it.
I am just a little unsure of this toe suggestion,obviously the shutter that will have the fall set on it will run paralell to the one you are suggesting using for the toe but is the shutter for the toe set level or same as hanging shutter as you put it which will have fall on it.
Hope this helps.
sean.
Posted: Mon Jun 02, 2008 8:55 pm
by Tony McC
Naah - it's 3.0m LONG and 300mm deep.
Posted: Tue Jun 03, 2008 6:07 am
by seanandruby
At those depths m8 it is really out of the scope of the DIYer. i would advise you contact a structural engineer foir H S resons. the slab will almost certainly need a reinforced cage. maybe you could drop the levels and incorperate a set of steps. 
Posted: Tue Jun 03, 2008 10:34 am
by sako
I think there is some missunderstanding here,i will try to explain again.
The size of the concrete pad (forgetting about any thicknesses) is going to be 3600 x3000 and over the 3000 run the difference in the heigh of the ground from one end to the other is 300mm i am just unsure how best to make the 300mm fall up so that i only have about 100mm of concrete to put in.
If i had to do you think i could just fill it up with concrete which would mean having a varying thickness of concrete (fall of ground)?
hope this helps.
sean.
Posted: Thu Jun 05, 2008 8:57 pm
by sako
Thanks for all the replies.I think i will have to just shutter it and fill with 200mm of hardcore which will then allow 100mm of concrete.
Does it cause any problems if your concrete is not a consistent thickness? (will be 100mm thick min)
sean.