Setting out on a slope

[oldkettle]

I've watched quite a few videos showing how to set out with batter boards - all very clear and easy to follow. But I can't find one showing the same process on a slope. I.e. when one corner is 1.5m below the other, do I need my batter boards (and the strings) to be 1.5m or even more above the ground in this corner? I would need a step ladder just to check the string  Any pointers?

It's only one corner which is so low, the other two are 700-900mm lower than the highest point. 

 

Won't be surprised if the answer is "excavate a larger area first, then set out on a flat surface.

 

TIA

[nod]

You can use a laser and detector and a staff 

[JohnMo]

Get the area marked out by a surveyor using GPS. No guess work.

[oldkettle]

8 minutes ago, nod said:

You can use a laser and detector and a staff 

 

I do use a laser. But one needs to leave something on the ground - impossible to keep 2 lasers (for all 4 sides) on for hours and hours.

 

8 minutes ago, JohnMo said:

Get the area marked out by a surveyor using GPS. No guess work.

 

I may do this eventually (or let groundworkers get their surveyor for it). But I am curious how this problem is solved in general: surveyor still needs to leave some marks pointing at the 4 corners of the building which would still be visible after digging starts - how does this work?

[gavztheouch]

Why is one corner so low? Are you going to build it up or cut the rest down?

[Russell griffiths]

Find a very local surveying company 

you want them on site probably 4 times. 
1. They will set out the site strip roughly 2m wider in every direction. 
2. They set out the foundations to 50-60mm accuracy 

3. They set out the walls onto the concrete foundation to mm accuracy. 

4. Drain locations within the house footprint to mm accuracy. . 
 

we had one more visit to plot the location of the piles. 
£400 well worth it. 

[saveasteading]

4 hours ago, oldkettle said:

1.5m or even more above the ground in this corner?

It is normal to set the batter board a convenient height above ground level, both for eying between them and for an easy sum. so 1.5m is ok.

the one at the top of the hill points into the ground, showing the cut.

 

There is a lot to be said for them as they work from one side to the other , with no need for calculating the finished level at each spot.

 

 

if you also make a 'traveller, of the same height (1.5m) then it simply eyes through and you now roughly how much to excavate. you can make feet for them so they stay standing

they don't steam up in the rain or cost hundreds or more if they fall over.

for the precision stage you either pull a fishing line tight across them, or then use  a level.

 

primitive but a good option. they look cool  on site too. especially painted red and white.

 

or get someone else to do it.  I resist because I don't need to, and because they've made expensive mistakes on my sites when made to use them. 

Always step back from your or another's setting out and decide if it looks right.

[nod]

If you feel confident you can hire a GPS I had one fitted in the digger I borrowed Simply follow the screen like a sat nav Gives you all the depths and steps No marking out needed But you need a SE to feed the info into the software 

[oldkettle]

10 hours ago, nod said:

If you feel confident you can hire a GPS I had one fitted in the digger I borrowed Simply follow the screen like a sat nav Gives you all the depths and steps No marking out needed But you need a SE to feed the info into the software 

 

Yes, I really liked this option when I read how you did it. Unfortunately AFAIK this only comes with large diggers and access is simply not there for anything larger than 3t, even 5 is unlikely. 

[oldkettle]

20 hours ago, gavztheouch said:

Why is one corner so low? Are you going to build it up or cut the rest down?

 

It's just how the ground looks like. Lifting the lower corner is not a good option as would have to retain the newhigher level and the width is limited. 

 

Trying to build into the slope. It also gives me a bit of an extra ridge height due to PD rules. 

[oldkettle]

19 hours ago, Russell griffiths said:

£400 well worth it. 

I very much doubt 4 visits would be done for that amount in Surrey though 🙂

 

But how do they actually mark it? 2m in each direction will mean an even larger height difference, likely around 2m. Or do they just mark corners with certain levels and leave the rest to a laser with a traveller? 

[Kelvin]

Our site is on a significant slope. They dug it out (cut and fill) to get level ground. Survey guy used the CAD foundation drawings to set it out and marked it on the ground. This was also loaded into the digger. Digger driver dug out the trenches back to original ground. 

[oldkettle]

1 hour ago, Kelvin said:

Survey guy used the CAD foundation drawings to set it out and marked it on the ground. 

So at this stage was it just a few lines on the ground? The base level marked separately on a post? 

[Kelvin]

27 minutes ago, oldkettle said:

So at this stage was it just a few lines on the ground? The base level marked separately on a post? 

The whole house trench was laid out on the ground and yes the base level was marked on a post which was still in the ground last time I checked. They marked a few levels around the plot as a check. 

Edited April 28 by Kelvin