DRon's Project

[DRon]

So, Im starting to build my own one story extension in a couple of weeks with the little money we have saved up
(Digging foundations 21st july - I might upload before and after pics if anyone is interested)

my first question in this epic task is....


"I need 6.5m3 of concrete for foundations (3mx6mx3m at 900mm depth & 600 width) what aggregate do I need to order and how much? same with concrete?"


your help is soooo appreciated, thanks in advance guys and gals!

 

[^woody^]

Are you mixing all this yourself? If not just tell the concrete company its for foundations

Otherwise, ask for "sand and gravel" or "mixed" aggregate and IIRC, 1 bulk bag is about 1/2 cubic metre and get seven cement per bag

I think there is a post or two from noseall about quantities which might be more accurate

But don't forget that you will need some for the floor (and cement for the walls) , so don't worry about over ordering. Build up each order to get a discount if you can

 

[stuart45]

Use readymix if you can. Mixing that amount up yourself is a lot of work and not cost effective..

 

[garyo]

Seconded - the volumetric mixer people will pour it for ~90+vat per cube - how much are your materials going to cost...

Upload some photos!

 

[DRon]

woody - I'm just working out price of both before deciding whether to mix myself or not as budget is quite tight! 1 bulk bag = 1/2 cubic metre, WOW looms like 6 cubic metres is alot of work! Thanks alot for the reply mate!


stuart45 - yeah seems like alot now, I'm just making sure I know what Im asking for before I get a price for each. Apparently pouring concrete companies charge waiting time aswell, because the lorry count get down my drive it might work out alot more expensive. Any tips on who is cheap to go with?

garyo - Im just waiting for a price for the aggregate and cement, I know someone who works at a builders merchant and said he should be able to get it at cost for me, I don't mind doing the work if I can rope some others in, going on what woody said though, 12+ bulk bags sounds alot.....is it??

Ill go grab some photos in a bit, just need to finish emptying the building that is currently there (im knocking down an existing dodgy lean to like building and then rebuilding properly...hopefully!)


Thanks alot guys, really appreciate it!

 

[jeds]

That's a lot of concrete. I make it more like 2m cube for a standard strip and still only about three and a half for a 500 deep trench fill?

 

[noseall]

Mixing 6m³ (12 tonnes of ballast plus 80 x 25 kg bags of cement) is a lot of hard work.

We now use a company that mixes what you use and they arrange for the pump too. He brings say 11m³ on the wagon and just bills you for the quantity he mixes so no worrying about expensive part loads or waiting time.

Cost of concrete is about £90 p/m³. He shoots it into the back of the pump hopper and the pump people squirt it all around the trench. All it needs is a bit of tamping, easy peasy.

The pump company we are using now only charge £150 for small loads.

We do tend to have a loose delivery of materials for the floor slab and the cavities as it can be a bit of a faff filling the cavs, wackering the infill stone, getting the inso' ready then having the slab pumped, all whilst concrete people are stood around.

You are unlikely to be able to buy the materials for less than what it costs to buy ready-mix.

 

[DRon]

Jeds - the dimensions for the extension are 3m x 6m x 3m at 0.9m depth & 0.6 width - have I worked it out correctly? - I just used an online concrete calculator (The plans say trend filled foundations 900mm minimum)


noseall - I think you have convinced me to go with the ready mixed concrete. So I just need to get a few quotes, I'm based in a village in Oxfordshire, so if anyone reading this has any recommendations, lemme know!
Ah ok, I assumed using a pump would be crazy expensive, I was just going to get a couple of mates to run back and forth with a wheelbarrow, hence the charge for waiting around!

Thanks again guys, all a steep learning curve! - really appreciate it!

 

[macadonald]

DRon,

I was quite relieved to see your post, I'm in the process of starting an almost identical project of knocking down an existing lean to extension and replacing it with a new single storey extension within permitted development. Also planning to do most of this as a self build and have just been talkign with concrete companies about foundations.

Just a suggestion, but during all of my research (and I stand to be corrected) I found that the best and most cost effective method of filling trenchfill foundations is not necessarily with ready mix, but rather the companies that mix on site. You may have already discovered this though.

A very useful website to read is:

http://www.myhouseextension.com/

I look forward to watching your posts and will probably be asking lots of questions myself. I will only start demolition in a months time.[/url]

 

[stuart45]

Jeds - the dimensions for the extension are 3m x 6m x 3m at 0.9m depth & 0.6 width - have I worked it out correctly? - I just used an online concrete calculator (The plans say trend filled foundations 900mm minimum)

You don't need to fill them right to the top. The 900mm minimum means the depth of the dig. Have another look at jeds figures.
You need some room for masonry up to DPC.

 

[jeds]

The minimum refers to the minimum depth of the trench - not the concrete. Even with trench fill the concrete would finish 300 or so below ground level. So in a 900 deep trench you'd only be on about 3.5 cube of concrete. Either way I wouldn't even consider mixing myself. Readymix is much easier and more reliable.

 

[DRon]

jeds & stuart45 - aaahhhh ok, thanks alot - that could have ended with me looking like a dick! I thought 900mm was the concrete. That makes it cheaper, which can only be a good thing!
yep, I have been told by builder to fill the trench 2 blocks below DPC. (Im planning to get some steaks hit into the ground and level them and then just fill the concrete to the top of them - that sound ok?)

macadonald - ah nice, wicked. Ill get some photos uploaded so you and everyone can see how I get on - should be 'fun'??? Something is bound to go wrong though!
How big is your new extension gonna be? Im hopefully knocking it down this week, we have a kid on the way (Jan) so it needs to be done by then! Better get a move on!!!!!!!

never heard of / found a company that mix on site? Have a link to any of them??

Cheers Guys - feel like a right noob!

 

[stuart45]

jeds & stuart45 - (Im planning to get some steaks hit into the ground and level them and then just fill the concrete to the top of them - that sound ok?)

quote]
Easier to put the stakes in the sides for trench fill and go just below them.

Untitled

• stuart45
• 16 Jul 2012
• 1

 

[maltaron]

Note that the building inspector will want to see the excavation and stakes(use these STAKES and eat yours) before you concrete.

 

[DRon]

Stuart45 - top tip, cheers mate. I'll find something to stick in the side.

Maltaron - cheers


Thanks again