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Have you dug foundations for extension?

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Chris_Pallet

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Hiya,
I honestly think there is some of the countrys wised on here... Especially in the off topic....

So just wondering if you have dug your own footings / foundations for an extension?
I'm considering it depends how much I will save....

Was it worth it?
Do you regret it?

Any issues?

What advice would you give?

Thank you kindly
 

eribaMotters

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Chris, first thing is how big is the workshop as you may be involved with building regulations due to size. When I lived in Essex my 8 x 5 m workshop needed regs as it was over the 30 square metre limit. I was asked to do a 600 x 600 mm ring with a double steel cage along with a 200 mm slab on top, all cast in one hit. All this 60m from the road. I refused, pushed the issue with the boss at Southend building control who eventually accepted a 450 x 450 mm ring with steel reinforcing and a 150mm slab cast later. On top of this sat a dwarf wall of 3 bricks then a studwork construction. This did not move or settle, which was a concern as the workshop was under three 40ft oak trees. It was a lot of work, but worth it.
You are unfortunate in your location as Essex clay makes for tough regulations. The house extensions needed 1500 x 450 mm trenches filled with concrete to full depth. Here on Merseyside where I now live they say 700 x 400 mm down to hard sand and fill with 200mm of concrete before blockwork starting of this thin strip footing with trench blocks.

Colin
 

treeturner123

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If you do it yourself, as per Colin PLUS where will you take the spoil? Don't forget that the stuff you dig out has been compacted so when you dig, it takes up more volume!!

It will not I believe, be counted as 'Domestic Waste' so you will probably be charged for it if you take it yourself or you will need a good few skips!

My advice, leave it to a builder. If he does it wrong, he will have insurance!

Phil
 

Jameshow

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I wouldn't as I value my back, my hands and time.

If you use a digger yourself unless skilled then it will be cheaper to call someone in to do the whole job. Often they have a tipper and will remove spoil cheaper than using skips

Cheers James
 

LJM

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As others have intimated, whether it’s worth it is down to your skills; I’m sure, as a woodworker, you’d be fine setting out, levelling and so on, with a little help form YouTube.

Operating an excavator efficiently (and safely) is another thing. I don’t find it difficult, but my twin brother doesn’t have the feel for it, especially with things like scrap[ing a surface get a level, or swinging the bucket in a straight line, when the machine is not sitting over the cut that you need to make. If you have the time to figure that out, bearing in mind that time is money, then things could be straight forward.

You do need space for the spoil, as others have mentioned; use a muck-away service (a big truck with a grab). It’s cheaper than a skip and a lot of the work is done for you, by the grab. Though you may be able to use some for landscaping.
 

Bm101

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I've dug (lots of) foundations for other peoples extensions in my youth. I could dig like a navvy when I was 23. I can drive a mini digger (or could).
One day the 40 year old odd fella driving asked if I wanted a go. Hesitant at first but in 20 mins time the boss pulled up and watched for a minute. After that the guy who used to drive it was on the barrow while I sat on the digger. 😬 I was well popular lol.
It is a knack and some people don't get it as LJM says.

I would never dream of doing it now for all the reasons listed above. The one exception would be if my personal circumstances changed significantly. Ie I was on farm land and could rid the spoil for free and I had more time than money. Say I was self building and had taken 6 months off etc... Otherwise I'd get someone else to do it personally.

Take 5 mins to calculate the volume of waste coming out, (think you will be astonished, convert it to tonnes than you can visualise it with tonny bags) then look at skip/waste prices. Then add your labour and time roughly and what you could have earned doing something else. You'll be slower than a pro. Also as said, sometimes they can get rid of waste cheaper than you can. Weigh it all up. LJM has it right about needing space for a grab lorry. It has to be efficient.
Are you 28 and full of beans with working hands or maybe not so up for the physical challenge.

Me personally these days, I'd be thinking Sod That.
 

Spectric

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When I lived in Essex my 8 x 5 m workshop needed regs as it was over the 30 square metre limit. I was asked to do a 600 x 600 mm ring with a double steel cage along with a 200 mm slab on top
That rings some bells when I lived down south, it is incredable that they may want footings 1.2 metres deep for a single story house extension yet the actual house was built on just 0.6 metres and all they say is that 's the current regs so no real reason and god help you if there are any tree roots present in the trench.

These days I would just get a groundworker in and leave them to it, I think 45 to 50 is the limit for digging with a shovel and even with a mini digger there is always something aligned to being hard work!
 

LJM

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If you do DIY, don’t skimp on the digger; get the biggest machine that can access the site. Do keep in mind that any excavation over 1m should be shored up, or battered back (slopped). Whilst the HSE are not interested in your DIY project, the rules are there for good reason.
 

Woody2Shoes

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Hiya,
I honestly think there is some of the countrys wised on here... Especially in the off topic....

So just wondering if you have dug your own footings / foundations for an extension?
I'm considering it depends how much I will save....

Was it worth it?
Do you regret it?

Any issues?

What advice would you give?

Thank you kindly
Yes (times five)
No
Not really (I have an engineering degree and took paid advice from a structural engineer in each case)
You can save money, but it can be hard work and there are lots of traps for the unwary.
 

Keith 66

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We had a big extension built on our house 18 years ago, southern essex , on a hill, clay. Because the house had been underpinned on a ring beam the new foundations had to tie into that, Trench was 1.3m deep 600w with piles 11m deep, 300mm void former underneath the beam & a fair amount of steelwork. We got planning permission on appeal as we fell foul of an obscure rule, (side isolation space in a conservation area) So as part of the appeal had to find examples where PP had been granted. So one saturday morning i go for a drive about the town & before long have spotted two examples for the list. A few streets later there is another actually at foundation stage. I knock on the door & a lady comes out, I explain that im having to appeal to the planning dept on a similar building project & she is most helpful, "Ill get my husband, he is working down there". She calls him & he is working in the foundations, these are deep about 2m & about 9m long. As he comes up the ladder & walks towards where we are the whole long trench behind him suddenly caves in without warning right where he had been.... He went as white as a sheet. Pure fluke i turned up out of the blue & caused him not to be under it all.
Deep holes in clay are dangerous.
As for Muck away, Our builder estimated about 8 grab lorry loads, by the time we removed the oversite & rest of the mud it was 18.
Back then it was £150 a load cash. Lord knows how much today.
 

RobinBHM

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Are you talking hand dig, or plant hire?

It is potentially a part of a project you can save money.....


If it's plant hire, a digger and a tracked skip loader will cost you around £500 for a weeks hire. If for some reason you need a bigger digger as the foundations are deeper, or you hit a problem (services in way, well etc) then you to get those machines collected and re hire.

Is drainage complicated? - that can slow you down.

What is access like? If you can pile up spoil for a grab lorry, it will be cheaper - if it's on your drive, you need to allow for 3 or 4 sheets of shuttering ply.

To calculate skips, as a rough guide soil fluffs up by between 1.5 and 2 times its original volume.

Be aware skip changes will also slow you down and nay mean extension to hire period.


As an aside: if say the building inspector makes you dig deeper (to reach load bearing ground and or trees nearby) then it will cost you more....but it will cost you more whether you are doing or a builder - he won't dig deeper for free
 

LJM

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Whoever does the work, be it you, ground workers or a general builder, will be working from a design specification required by building control and probably completed by an engineer; why not get to the point where you know what will be required before deciding whether it’s worth doing yourself?
 

LJM

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The other disadvantage to skips is that it’s easy to over fill them; even with them level filled (as it often demands on the side of them), I’ve been able to leave the skip wagon over weighted. You won’t have this issue with a grab.
 

RobinBHM

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The other disadvantage to skips is that it’s easy to over fill them; even with them level filled (as it often demands on the side of them), I’ve been able to leave the skip wagon over weighted. You won’t have this issue with a grab.
I know some builders who use a whacker plate on skips to get more soil in - you can substantially more in.
 

LJM

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I know some builders who use a whacker plate on skips to get more soil in - you can substantially more in.
depends on the size of skip and density of the soil; with a big skip it can become heavy enough that the front wheels of the wagon leave the ground as it lifts the skip, something a lot of drivers aren’t cool with.
 

francovendee

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I built and extension to the house and dug the foundations. I'd never do it again.
A lot of back breaking work that won't be done over a weekend.
I hit a section of clay at one end and the inspector made me go down another half a metre.
During the dig we had a tremendous cloudburst and I can still hear the sound of the sides collapsing into the bottom of the water filled trench. This meant a pump and expensive shuttering.
I hired skips to take away the soil, getting the wheelbarrow up a plank was also hard work.
If you can afford it get a builder in and do the nicer bits yourself.
 

Doug B

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I’ve hand dug the footings for two extensions & two workshops over the years & didn’t think it was particularly hard work if you are young & fit as I was in those days, that said I still regularly dig my allotment so what defines hard work will vary from person to person.
As to removing the spoil if you give it some fore thought you can usually find an inexpensive way of getting rid of it if it’s not solid clay etc, I levelled the back garden with the spoil from building my present workshop & when I built the extension on the house I got a trailer & sold most of it to a chap who wanted top soil, it really does depend on what you are digging out & where.
That all said I’ve worked on extensions where the footings have been one of the biggest individual costs of the job, it really does depend on many factors.
 

MARK.B.

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Only a few weeks ago a 8 yard skip was £145 where i live and a grab lorry taking 18 yards was £185 , so i had 4 of them as opposed to 8 or 9 skips saving around £600 (y):)
 

HappyHacker

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Get a digger in if it anything bigger than a small extension or you are fit and young. if you have not driven a digger before get one with an operator, it will be cheaper unless you don't mind spending time practicing. Driving one is not difficult but getting a trench dug out accurately is more difficult than a proficient operator makes it look.

On depth, I had a building inspector insist that I dug the foundations for a porch out to one metre. I objected that we had reached hard sandstone at 2ft and it was going nowhere. He told me in no uncertain terms that the foundations would frost heave if not one metre deep. I should have taken him for a walk through the village where many of the buildings have their brickwork built on sandstone above and below the ground. None have heaved in the last few hundred years.

When digging out a basement about seven foot deep the last foot had been dug out of solid sandstone, A JCB with a toothed bucket managed about half an inch per scrape. A different building inspector insisted that the concrete floor needed to be reinforced as the walls were to be built on it. The reason being the turning moment the walls would place on the concrete would cause the walls to sink and the middle of the floor to raise. He said if we did not put reinforcement in he would not pass it. He was unable to say how the floor would sink into the sandstone apart from saying there would be a turning moment on it.
 
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