Just how difficult is excavation work?

[Canski]

I hired a digger driver for £200 a day and hired the plant in. The speed he went was incredible he is so skilled and safe. I saved money by driving the dumper, setting out and holding the laser for him. At times we hit obstacles and I was glad he was there to deal with them. Money well spent and I saved a fortune on the quote I had from a ground worker friend. 

[Declan52]

There is a vast difference in a digger driver and a guy who can drive a digger. To learn that quick to undertake the actual footings is a massive risk. It's a lot harder than you think to dig a straight line and have the bottom flat. That takes a lot of experience. The cost implications of being out of line are massive. 

Hire a digger driver with his own machine in and give him a hand. Mark the site out and peg the corners and do all the dirty work and let him dig and earn his money. Help with the concreting and the other jobs he needs a hand with. 

If you really want to hire a digger in do it later on for tidying the place up and putting the road, paths, drainage etc in. There is a lot more scope here to not be as accurate as you need to be when doing the foundations.

[gavztheouch]

I would use steel tapes not gps to mark out. I’m marking out and digging my own foundations but I’m using an insulated raft foundation so the shape and size is not so critical as the isoquick foundation is pre manufactured. I just need to make sure it’s square.

 

I bought an old optical theodolite off gumtree which I have found useful and very accurate for marking out points on the ground in conjunction with a decent steel tape.

[saveasteading]

1 hour ago, gavztheouch said:

conjunction with a decent steel tape.

Zteel for ultra accuracy.

Big brand fibre tapes are OK too. They have the advantage of being more robust. 

There is an EU standard for accuracy.

NOT silverline.  I had two that were out by 100mm in 30m.  They obviously had zero quality control. An expensive error.

[joe90]

10 minutes ago, saveasteading said:

NOT silverline.

🤣 cheap shit.

[Russell griffiths]

All this talk about setting out. 
why

get a surveying company to do it, I used a local company so only 15 mins of travelling, hour and a half on site, you would have been at it for a couple of days trying to do my place. 
 

if you have for external corners on a box house then ok but anything more complicated it’s £2-300 well spent. 
 

I’ve seen lads with 20 years experience build on the wrong side of a line so 300mm out. 

[gavztheouch]

The ultimate accuracy is a class 1 tape which I think is about +-3mm over 30m, class 2 is +-6mm over 30m so not much difference. You can feel a fibre tape extending under pressure so steel is better as it has less flex.

 

I agree that if you want to get it done quickly get someone in. If you value your time then it will cost more doing it yourself too. It's a balance isn't it trying to figure out what you enjoy and think is worth tackling yourself just cause you want too.

 

I bought a theodolite like this one, although mine isn't digital. I plan on making a cad drawing of my founds with all the important points measured radiating out from one position. I can use the cad to calculate all the lengths and angles from that one reference point. Then I can use the tape and angle measurements made with the theodolite to plot them out. To double check I can then measure the distances between the points, that will tell me if I got it right.

 

I mark the points using a 45x45mm wooden batten driven into the ground. I get this near the mark and then use a nail hammered into the wooden stake as the real mark. I usually need a few attempts at getting the nail in the right position. I look through the theodolite sight and make a mental note of where the nail needs to be by looking at notable marks in the wood like knots and wood grain. I walk over to the stake at hammer the nail in lightly, then I walk back and check the position and adjust if need be until it's right. You do this at the same time as making sure it's at the right distance by using your steel tape. You can strike an arc with the tape and a pencil to make a mark of the distance on the wooden stake to help.

 

 

 

[saveasteading]

I did top end land surveying for several years. But I haven't used a theodolite or its descendants  for decades. 

For a straight forward building I use two tapes and pythagoras.

Pegs are good, measured a set distance (offset) from the line so it isn't dug up.

For concrete I like a pin in the ground to show the finished level, then no mistakes are made.

 

[SteamyTea]

9 hours ago, gavztheouch said:

The ultimate accuracy is a class 1 tape which I think is about +-3mm over 30m,

https://en.wikipedia.org/wiki/Tape_correction_(surveying)

 

  

On 24/02/2024 at 10:11, saveasteading said:

Pythagoras to check the square

Can do more than that.

https://www.mathsisfun.com/sine-cosine-tangent.html

 

 

Also worth noting where 0° is, which direction the angles are counted (clock or anti-clock), if degree or radians are used, and precision and accuracy (how close they measurements are to each other or the true value).

Edited March 1 by SteamyTea