Ready mix concrete question

[diy457]

We just hired a builder on a labour only job so im obviously paying for all materials. Wasnt sure about it but thought id give it a try. I might learn abit. I like the guy so far and he came via 2 strong recommendations so all should be well (i hope).

However, today we talked abit about materials and roughly how much itll come too... and we got to concrete chat for foundations and said he would get ready mix. He said itll save 3 days time and be better quality foundations blah blah. It only dawned on me just now that im already paying him labour and then paying extra for the cost of the ready mix.... I should get 3 days labour back right? It's only going to take about 1 hour too pour. I got a quote for 3.6 cubic in North London for ready mix and it was around 500 inc vat. Expensive i think.. is it?

1, However, can anyone give be a rough idea of the cost difference - materials only - for filling foundations of 3.6 cubic, if all separate materials brought and self mixed on site.

2, And how long would it take x number of guys to manually mix & fill 3.6 cubic foundations for a kitchen extension?

3, OR How much cheaper might it be the old school way percentage wise? 20%? 30%? 40%?

Im going to speak to him tomorrow as im worried the kitchen floor is concrete (i think) so he will call them back for that.. and some largish garden foundations for slabs to be done as well... itll cost way more im sure this way. First thoughts are it seems like it's just transferring labour effort into materials cost. if it's not too much difference i don't mind... but is it alot of difference?

Help appreciated. Thanks.

 

[SALL2009]

What is the size of your foundations?

 

[freddiemercurystwin]

You can't seriously expect one bloke to mix concrete and barrow foundations with 3.6m³? Is he a Terminator?

 

[garyo]

Around my way it's around £90+vat a cube. This isn't far off the price I can buy the raw materials at, so it's an easy choice to use ready mix.

Is your alternative to trench-fill readymix to pour a strip foundation and then lay blocks, or are you proposing to hand mix a trench-fill foundation pour?

 

[diy457]

1, It's 3.6 cubic metre (as calculated by ready mix company when i asked for quote) as long as the inspector doesn't say go deeper. 2 wall extension (3m + 6m) as party wall is built by neighbours = 9m length total and 1m deep x 600cm wide.

2, He is no terminator... but he does have a team of about 3-4 men so not unreasonable for them to do it manually in a day? I don't know. Pouring it ready mix will take about 1-1.5 hours.

3, 550 inc vat is what i was quoted yesterday = for 3.6 cubic m = £152 per cube (!). Ill shop around.

At this stage im just going with the flow... im happy to buy - no problem - just want to make sure there isnt a massive price difference eg, 40-50%, and he uses it everywhere, which dents my budget - as im already paying him for his time. Any cost comparisions - manual vs ready - would be interesting to learn.

Im not a builder and havent had much building work done in my lifetime that I've been directly involved in so i really don't know what i should expect from a builder filling foundations. Im just trying to broaden my awareness.

And yesterday i phoned up 2 skip companies and they told me the rate has gone up about £100 since last week cos of gov waste disposal price increases... But said the big companies are planning to protest this weekend so maybe they will freeze the price for 6 months while they 'review' the decision... I have to order a skip for friday...fingers crossed..

Thanks.

 

[freddiemercurystwin]

9m length total and 1m deep x 600cm wide

9x1x0.6 is 5.4m³.

Or did you mean the trench is 1m deep but the foundation is about 0.7 deep?

 

[diy457]

9m length total and 1m deep x 600cm wide

9x1x0.6 is 5.4m³.

Or did you mean the trench is 1m deep but the foundation is about 0.7 deep?

Yes, my mistake, trench will be 1m but concrete up to 0.7 or 0.8 deep (then dpc bricks?).

He worked it on 9m long X 0.8 deep X 0.5 wide = 3.6.

After the phone call i looked at the drawings at should be 9*0.8*0.6= 4.32... so more cost.

 

[jeds]

You need to give the detail of your foundation because it's not clear. A standard strip would be about 250 thick concrete in a 900 deep trench. Call it a metre deep if you like. 250x600x 9metres is 1.35m³ of concrete. You'd be trench filling to more than 600 thick to get anywhere near 3.6m³. But why would you trench fill a 1m deep strip?

Personally I don't normally allow builders to mix on site unless I know them well. It's because a lot of them are muppets. And muppets aren't always good at volumes and measurements and quality control and stuff. There's not a lot of difference in cost so I'd rather know my foundation is right now than find out it's not in 5 years time when the muppets are no longer to be seen.

I heard today that landfill tax is going up to £65 a tonne. If that happens a skip full of heavy mixed masonry would cost about five or six hundred quid to tip. Brilliant eh. Still, great opportunities coming up for people who clean up fly tipping.

 

[jeds]

He worked it on 9m long X 0.8 deep X 0.5 wide = 3.6.

Crossed in the post. This bloke who worked this out for you. Wasn't trying to sell you some concrete was he?

 

[diy457]

Personally I don't normally allow builders to mix on site unless I know them well. It's because a lot of them are muppets. And muppets aren't always good at volumes and measurements and quality control and stuff. There's not a lot of difference in cost so I'd rather know my foundation is right now than find out it's not in 5 years time when the muppets are no longer to be seen.

I heard today that landfill tax is going up to £65 a tonne. If that happens a skip full of heavy mixed masonry would cost about five or six hundred quid to tip. Brilliant eh. Still, great opportunities coming up for people who clean up fly tipping.

Thanks for the first paragraph opinion. I want a quality foundation. And if the cost ain't that much more then no problem.

I don't know about the trench size properly. Im not going to guess. But at 3.6 cubic for 550 (inc vat) or £152 per cubic meter is should be enough info for someone to give me a like for like cost - manual vs ready approx PERCENTAGE difference. And i appreciate the more ready you buy the cheaper it gets.

The waste increase... yes....prob *NOW* going to be 20%+ of my costs (i've grouped with materials costs budget)

 

[^woody^]

A shallow strip and blockwork foundations may be more appropriate, and more paractical

 

[diy457]

fyi - foundation & floor drawing info.

I don't know what shallow strip blockwork is without googling .... im just wondering what the approx percentage price diff of ready vs manual filling of foundations is ... Anyway, im going to get best price for ready mix once the trench is dug and HOPE it's the only 'extra' cost that comes up. I can't think where else i might have miscalculated materials costs.... but prob have.

 

[freddiemercurystwin]

Well a normal strip foundation would be 250mm deep, still down to the same depth. But would need more blockwork below ground level to get you back up. So is a cost exercise. Really depends how much effort you want to put into saving £50 or so here and there!

The bottom line is you need to get your builder to quote for doing it manually + materials and then you need to get actual quotes for the right amount of Readymix for your job on your chosen day in your location. The advice given out on the forum can only take you so far .........

 

[diy457]

Thanks freddy. I was just checking since this is a new situation for me. Ill take a 'suck it and see' this time. If its only about £50 - 100 quid this one time then its no big deal. I don't want to get too fussy. I don't mind opening the wallet alittle if they do a good job with the minimum interuption & stress for all.

 

[noseall]

If ground conditions allow, i.e. they are fairly level, then the optimum finished height of foundation concrete should be 525mm below dpc.

Mass filled foundations are by far the most economical way to build the footings.

The only clincher being services or similar crossing the trench low down that would require lintelling over rather than submerged in the concrete.

Ready mix shot straight into the trench is the cheapest way of laying concrete.

The next best thing is pumped concrete.

Then miximate and a herd of barrows.

Then mixing your own.

When it comes time to doing the floor slab and filling the cavities, usually the most economical way IS to have ballast loose and mix your own as these are often smaller quantities.