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What tools/electronic gadgets to set out?


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I am currently part way through the conveyancing for my plot purchase. The owner of the plot says he has no problem with me visiting the site to confirm plot dimensions and the planned house position. My first setting out will only be a trial run and so I do not wish to spray any marking lines just yet.

 

What tools will I need to to set-out the foundation plan?

 

I am also concerned about gradients for a suggested foul and surface water drainage plan but I am confused about the capabilities of sub £100 lasers.

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Depends very much on the nature of the site and how accurate you need to be.  Some build methods need more setting out accuracy than others, too, as they don't give much leeway for things like the position of ducts and drains coming up through the floor.

 

You could get away with a self-levelling laser, a staff with a laser detector and a surveyors tape for a fairly level site, or you might need to up the stakes and use a surveyors tape and a dumpy level (not as easy on your own), or you may need to do as we had to, and use a Total Station.  We had to use a Total Station for two reasons, one was the gradient and topography of the site meant that we just couldn't get the accuracy needed using a tape and level initially, as we needed to be very accurate in digging out for the retaining wall that forms one boundary, and provides a reference point in one corner for all the other laying out.  The second reason was that our chosen build method required the drain and ducts to come up though where the floor would be to within a few mm, as they all needed to be close to finished internal walls in the house.

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21 minutes ago, JSHarris said:

Depends very much on the nature of the site and how accurate you need to be.  Some build methods need more setting out accuracy

 

 

Sorry I missed some essential info.

 

Trenchfill foundations, concrete beam/insulation/screed ground floor, brick & block two story wall construction.

 

Probably 0.5m variation in the site across the foundation plan area and hopefully less than a 1:30 gradient in the longest drainage run of say 30 meters.

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Sounds easy enough to layout with a surveyors tape and a decent level to me.  Use triangulation to check you have things square and try to establish one or more fixed reference points that you are certain are in the right place, and won't get moved.  If working with a tape and level it's often easier to try and set out a reference baseline of a fixed and known length between two known reference fixed points, as you can then triangulate any other point on the site from that baseline with the tape and a bit of simple trigonometry.

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Sounds similar to ours.

 

I set it all out with a laser level and a surveyors tape measure.  For temporary marking I used a roll of red and white marking tape stretched between canes. Then sprayed with floor marking paint when I was sure it was all correct.  I had a planning condition that I had to mark the site and the planners needed to visit and check the marked location, and then I dug to exactly that, so there can be no issues with it in the wrong place.

 

On the basis the trench foundations were conveniently 1 digger bucket wide, I measured and marked the centreline of each trench and dug to that.

 

When the builders came to pour concrete and build the footings, their man did not believe I could possibly have got the trenches in the right place by doing that so they spent a whole morning setting out profiles and string lines and measuring then re measuring and concluded my trenches were spot on.

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I have already discovered how much O-Level trigonometry I have forgotten.

 

I still think I should buy a basic laser distance measuring device so that during build I can keep a covert eye on the accuracy of work by various subcontractors e.g. check how straight/square internal walls are or stud wall frame positions.

 

Looking online I see that a handheld laser measure starts under £50, hobby laser spirit levels are < £100 and a basic surveying kit for measuring incline is about £200 but I am unsure what the features mean at this point.

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The laser distance gadgets are OK, but personally I'd use a tape, as it's pretty foolproof.  I have an old Fibron surveyors tape that must be over 30 years old, and still does a very good job.  It doesn't need batteries, either, and it doesn't go wrong if it gets wet!

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A tape and water level should be perfectly adequate for setting out, but laser measures are brilliant tools. I bought one of these https://www.powertoolworld.co.uk/bosch-glm50c-professional-laser-rangefinder-0-05-50m recently and wish I'd got one ages ago.

 

They're not wonderful outside as it can be difficult to see the spot in bright light, but you can measure things single handed that would be very difficult with a tape. E.g. I'm rebuilding some outbuildings and I wanted to check that I'd got the rafters parallel over the length of the shed. Standing on a ladder 2.5M above ground I could measure 9M quite easily with the laser measure, not at all easy with a tape. It also has an inclinometer so easy to confirm the roof slope is right.

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I have a Leica rotating  laser level which is great for levels but I chose not to buy the one that can do slopes automatically which I now wish I had. Also have a total station which is excellent but the bosch laser range finder is almost as good at measuring distance as it is but as said above you cannot see the dot at any distance outside in the sun. That is where the TS is so good as you look through the scope line the cross wire up and it measures everything even taking the curvature of the earth into account if you want it to. The only draw back is the 1000 page manual and all the post processing you have to do to line everything up. I have now created a fixed base point I can bolt it on and put several backsight targets up so I can be sure where it is and what its orienation is. 

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We had a great advantage when using the Total Station as we found one of the Ordnance Survey spot height nails at the side of the lane adjacent to where our drive was going.  The position and exact height AOD for this was on the DXF file I downloaded from the Ordnance Survey when creating our site plan, and by pure chance you could see almost every point on the site from that nail.  Every time we wanted to check anything really accurately we could just set the TS up exactly over the nail and measure from there.  To save having to go out in the lane for the day to day measurements, we set up another fixed reference point right in the corner of the plot, where it wouldn't get disturbed, using the TS to fix that. 

 

That nail in the road has been a godsend, in several ways.  The last was when a neighbour complained to the planners about our roof being too high, when ten minutes standing in the lane with the planning officer and the TS proved that the roof was really a bit lower than we'd stipulated in the plans (probably because I added 100mm to the ridge height in the planning application, just as a precaution.........)

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You guys have saved me some dosh here as I have curtailed my desire for a hi-tech surveyors laser. My revised plan is to buy that Cotech end-of-line basic function laser measure for under £40 and then a water level gauge for £25. I have two survey tapes in my tool kit already.

 

This basic kit and some schoolboy trigonometry should be enough to:

  • Set out a trial foundation plan on site to verify the suggested building fits the plot.
  • Measure gradients to then calculate excavation effort.
  • Lay out a drainage plan to measure falls.

Will the cheapest water level gauge with 20 meters of connecting tube be ok? Would a 10 meter tube settle faster? 

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  • 2 weeks later...

I bought a rotating china unbranded laser

you can’t see the laser outside for love nor money ! . Comes with an ir sensor that beeps faster as you approach the level laser . Been brilliant ! . Also have a Stanley cubix for internal levelling - dead good also . I think with those 2 and a spirit level can’t imagine I can find an excuse not to be level !!! 

Edited by pocster
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