? About foundations for the brainy ones

zedhed · 15th February 2018, 10:40

Hi folks.need to ask a question about my garage foundations on how much ballast and cement i need.so all the foundations are 1 metre deep.there are 2 sides at 7 metres long and then theres the back at 4 metres.question is how much will i need if im filling to within 6 inches of the top.

another_clean_sheet · 15th February 2018, 11:12

Just work out how many cubic metres the foundations there are and then use this calculator. https://www.diydata.com/general_buil...ulator_2_m.php
I would suggest with that volume you need to buy Readymix

zedhed · 15th February 2018, 11:25

Quote:

Originally Posted by another_clean_sheet

Just work out how many cubic metres the foundations there are and then use this calculator. https://www.diydata.com/general_buil...ulator_2_m.php
I would suggest with that volume you need to buy Readymix

Ok thanks bud.readymix out of the question really as your talking a £1000 plus.missus is moaning already and ainy really spent nothing yet.

Darcydog · 15th February 2018, 12:16

I too would recommend Readymix for that volume. You could do it by hiring a mixer but it would be a lot of work. Also check out the cost of the materials - I suspect the savings compared to ready mix will not be that great.

Plus you have the possibility of inconsistency as well as the issue of doing a series of “pours” rather than one big one.

When we were looking at foundations for a conservatory - one option was putting in concrete piles with threaded bar - quite small ones, but quite a few of them - and then a frame bolts onto the pile.

I’m sure the firm did outhouses and garages as well as conservatory’s.

The system was a bit cheaper than traditional foundations - but the main advantage was ease of construction and speed.

Might be worth checking out.

Fox3 · 15th February 2018, 12:35

What width are you digging at? 600mm?

Two of us mixed 10 cube in a day with a mixer last year, it was just doable in a day, although was a long old day. We used 16t of ballast and two pallets (120 25kg bags) of cement!

When I worked it out ready mix would have been cheaper, and I get materials at trade prices!

This was for some 100mm floor slabs, and the way it worked (one barrow every five minutes or so) was perfect.

If your just chucking it down a hole for founds I'd definitely recommend ready mix.

If you get a volumetric type mixer, they'll mix on site so you just get what you need, and it worked out cheaper.

-

But in answer to your original question, first you need to calculate how many cubic meters of concrete you need.

Then, for one cube, you need :-

• 320kg of cement (13no 25kg bags)
• 1670kg of ballast (About two dumpy bags, these are usually about 800kg)

Based on £5 a bag of cement, and £40 a dumpy bag of ballast, you’re looking at £145 per cube.

Ready mix is around the £100 a cube mark, and all you have to do is chute it in, or barrow if you can’t get the truck close.

Avulon · 15th February 2018, 12:39

A triangular garage?

Anyhow - don't for a moment consider hiring a mixer and mixing the concrete and pouring it yourself - If you can't afford readymix being delivered then I'd suggest you hardcore as if concreting then sand and slab on top*. for a 7 metre by 4 metre rectangular garage you'll be looking at around 3 cubic metres of ready mix at around £70-80 a m3 ? So around £250. What type of garage are you going to put on It? Concrete, brick, wood? - the lighter the garage is the less of a base you'll need. You'll only be able to use a wooden garage on a slabbed base. Below the concrete and in normal conditions you'll probably want around 20-50cm of hardcore, you may need a lot more if the ground isn't good.

One further option I've not found discussed is to treat the garage wall as any other freestanding wall and make proper adequate footings for the walls (don't forget the weight of the roof!) and then a lighter simpler base inside the garage.

Daveluck · 15th February 2018, 16:36

Quote:

Originally Posted by zedhed

Hi folks.need to ask a question about my garage foundations on how much ballast and cement i need.so all the foundations are 1 metre deep.there are 2 sides at 7 metres long and then theres the back at 4 metres.question is how much will i need if im filling to within 6 inches of the top.

Blimey, a meter deep? How high are you going?

Personally I'd lay 200mm of well compacted hardcore, then poor a reinforced slab at 150 -
200 mm deep. Unless your building 2 stories high and parking HGV and its all going to be through traffic that's enough.

zedhed · 15th February 2018, 20:36

Quote:

Originally Posted by Daveluck

Blimey, a meter deep? How high are you going?

Personally I'd lay 200mm of well compacted hardcore, then poor a reinforced slab at 150 -
200 mm deep. Unless your building 2 stories high and parking HGV and its all going to be through traffic that's enough.

Reason for being a metre deep is large surrounding trees just 3 metres away.ideally it should be deeper but just not willing to take anymore out.it will be built from concrete blocks,and floor will be slabbed for now anyway.still thinking of a pit though

might just fill 2 thirds of the trench tbh if its gonna be that expensive.at the end of the day all this was dug out by myself and by hand

.also got rid of all the soil down the tip,so am doing everything possible to save money.

Daveluck · 15th February 2018, 20:57

Quote:

Originally Posted by zedhed

Reason for being a metre deep is large surrounding trees just 3 metres away.ideally it should be deeper but just not willing to take anymore out.it will be built from concrete blocks,and floor will be slabbed for now anyway.still thinking of a pit though

might just fill 2 thirds of the trench tbh if its gonna be that expensive.at the end of the day all this was dug out by myself and by hand

.also got rid of all the soil down the tip,so am doing everything possible to save money.

Sorry didn't realise you had already dug it! Been a while since ive dug strips out by hand...my back is aching for you in sympathy.

The last garage I built I ummed and ahhhed about a pit and decided not to because of all the extra work vs actual use I would get out of it.

But I did pour a slightly deeper slab just incase I managed to get around to buying either a 4 or 2 post lift.

alanaslan · 15th February 2018, 22:19

Quote:

Originally Posted by zedhed

Hi folks.need to ask a question about my garage foundations on how much ballast and cement i need.so all the foundations are 1 metre deep.there are 2 sides at 7 metres long and then theres the back at 4 metres.question is how much will i need if im filling to within 6 inches of the top.

Hi you are looking at close to a 20m3 pore, to buy materials to hand batch will set you back more than if you were to get in a spot mix unit, a full size spot mix unit carries enough material on board to make close to 40 tonnes. Concrete weighs in around 2.25 to 3 tonnes per cube depending on material used in construction.
You would be hard pressed to Hand mix even with a cement mixer to manage this kind of work not to mention the consistency of the pour. I know when I did my neighbours extension we had to go down close to 10 feet on a found that was ten feet by fifteen feet.
The depth was insisted by the district planners. We had to do the pour in two batches as the volume was greater than one spot mix unit could make in one pour. A normal cement mixer that you see on the roads hold around 8 cubes.
For the volume you are looking at and to have the strength within the slab you will be looking at a couple or three layers of rebar to ensure the strength in the slab. With the volume of the found the cheapest way to lay a slab of that size was spot mix who were about 20 % Cheeper than having 3 jägers and about 30% less than buying the raw materials to mix by hand. Laying a found slab is not cheep. Think we were close to three grand for the extension slab next door and that was with a very nice man who’s load was meant to go else where but had been cancelled so he very kindly dumped the junk load in our hole a very nice man.
Doing a quick sum in my head you would need close to a pallet and three quarters of cement and close on a four dozen 1 tonne bags of sand and type 2. This is why builders hold their slab pour in large batches the product has test cubes made 1 tested 1 stored for reference these are cured in a microwave and the cubes are about ten inch square.
If all is well then the found is pumped in one pour being pumped to the required area and further test cubes taken during the pour
To ensure quality and have reference proof.
Sorry to conclude that the Cheapest way for you to lay your found is to get it from a spot mix company look around many do good deals and they will be cheeper than buying the stuff yourself.
Best of luck. Let us know how you get on, remember on that size of found you will need at least two Or three layers of rebar. A big job.
Alan the tight Scotsman

Sent from my iPad using Tapatalk

15th February 2018, 10:40	#1
zedhed Posted a thing or two zt saloon turbo Join Date: Sep 2015 Location: Tipton Posts: 1,461 Thanks: 1 Thanked 167 Times in 132 Posts	? About foundations for the brainy ones Hi folks.need to ask a question about my garage foundations on how much ballast and cement i need.so all the foundations are 1 metre deep.there are 2 sides at 7 metres long and then theres the back at 4 metres.question is how much will i need if im filling to within 6 inches of the top.

15th February 2018, 12:35	#5
Fox3 Avid contributor MG ZT CDTi and MG ZT 190 Join Date: Oct 2016 Location: North Yorkshire Posts: 188 Thanks: 53 Thanked 45 Times in 30 Posts	What width are you digging at? 600mm? Two of us mixed 10 cube in a day with a mixer last year, it was just doable in a day, although was a long old day. We used 16t of ballast and two pallets (120 25kg bags) of cement! When I worked it out ready mix would have been cheaper, and I get materials at trade prices! This was for some 100mm floor slabs, and the way it worked (one barrow every five minutes or so) was perfect. If your just chucking it down a hole for founds I'd definitely recommend ready mix. If you get a volumetric type mixer, they'll mix on site so you just get what you need, and it worked out cheaper. - But in answer to your original question, first you need to calculate how many cubic meters of concrete you need. Then, for one cube, you need :- • 320kg of cement (13no 25kg bags) • 1670kg of ballast (About two dumpy bags, these are usually about 800kg) Based on £5 a bag of cement, and £40 a dumpy bag of ballast, you’re looking at £145 per cube. Ready mix is around the £100 a cube mark, and all you have to do is chute it in, or barrow if you can’t get the truck close. __________________ 2003 ZT+ CDTI Last edited by Fox3; 15th February 2018 at 13:05..

15th February 2018, 12:39	#6
Avulon This is my second home 1.8t Tourer Join Date: Oct 2011 Location: Tanelorn Posts: 4,830 Thanks: 956 Thanked 1,148 Times in 916 Posts	A triangular garage? Anyhow - don't for a moment consider hiring a mixer and mixing the concrete and pouring it yourself - If you can't afford readymix being delivered then I'd suggest you hardcore as if concreting then sand and slab on top. for a 7 metre by 4 metre rectangular garage you'll be looking at around 3 cubic metres of ready mix at around £70-80 a m3 ? So around £250. What type of garage are you going to put on It? Concrete, brick, wood? - the lighter the garage is the less of a base you'll need. You'll only be able to use a wooden garage on a slabbed base. Below the concrete and in normal conditions you'll probably want around 20-50cm of hardcore, you may need a lot more if the ground isn't good. One further option I've not found discussed is to treat the garage wall as any other freestanding wall and make proper adequate footings for the walls (don't forget the weight of the roof!) and then a lighter simpler base inside the garage. __________________ Need a T4 ?:* T4 Owners Map thanks to Stevestrat ( use at your own risk) Where?: https://en.wikipedia.org/wiki/Tanelorn Mods/Retrofits: PCV vortex 'filter'; bluetooth; inline thermostat; reversing sensors; plenum spyhole ; headlamp washers ; Diy mp3 player replacing CD multichanger; FBH with remote; Headlamp washers; black/chrome front grille, rear blind; Xenon projectors To do: puddle lights; 2 Din cd/nav to fit; boot release button

15th February 2018, 11:12	#2
another_clean_sheet Posted a thing or two Rover 75 CDTI Tourer Join Date: Nov 2014 Location: Great Bardfield, nr Braintree Posts: 1,416 Thanks: 303 Thanked 436 Times in 317 Posts	Just work out how many cubic metres the foundations there are and then use this calculator. https://www.diydata.com/general_buil...ulator_2_m.php I would suggest with that volume you need to buy Readymix

15th February 2018, 12:16	#4
Darcydog This is my second home Join Date: Jul 2014 Posts: 5,428 Thanks: 3,123 Thanked 3,170 Times in 2,096 Posts	I too would recommend Readymix for that volume. You could do it by hiring a mixer but it would be a lot of work. Also check out the cost of the materials - I suspect the savings compared to ready mix will not be that great. Plus you have the possibility of inconsistency as well as the issue of doing a series of “pours” rather than one big one. When we were looking at foundations for a conservatory - one option was putting in concrete piles with threaded bar - quite small ones, but quite a few of them - and then a frame bolts onto the pile. I’m sure the firm did outhouses and garages as well as conservatory’s. The system was a bit cheaper than traditional foundations - but the main advantage was ease of construction and speed. Might be worth checking out.