Russell griffiths Posted February 19, 2018 Share Posted February 19, 2018 Is there any sort of app or something so I can mark a datum height above see level on a stake. Just having a rough site clear and want to get a general feel for where finished floor level will be before I scrape off to much. I will be getting the surveyors back to set out properly, just want to do a bit of rough levelling. Cheers. Link to comment Share on other sites More sharing options...
Onoff Posted February 19, 2018 Share Posted February 19, 2018 App? Can of spray paint, wooden stake(s) and a Sharpie? Link to comment Share on other sites More sharing options...
ProDave Posted February 19, 2018 Share Posted February 19, 2018 You don't need an absolute datum. I hammered a row of nails into a substantial fence post at the highest corner of my plot. That is my "Temporary Bench Mark" and all my heights for planning on all the drawings were referenced to that TBM (it is still there should anyone wish to check anything) Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 19, 2018 Author Share Posted February 19, 2018 What I need to do is find a point above see level 88.35 to be exact. The nearest bench mark to me is 300m away and I don’t want to have to transfer that into the site when the surveyor will do it in a heart beat, just need to get it roughly right so I can scrape of a bit of top soil. Link to comment Share on other sites More sharing options...
ProDave Posted February 19, 2018 Share Posted February 19, 2018 Why that level of precision? All my planning was done and agreed with reference to my TBM no reference whatsoever to and absolute height. What's the height accuracy these days of the average GPS? Link to comment Share on other sites More sharing options...
dpmiller Posted February 19, 2018 Share Posted February 19, 2018 Any OS maps with contours for your area? Link to comment Share on other sites More sharing options...
albert Posted February 19, 2018 Share Posted February 19, 2018 I have had the same problem this week on a garage, planners want proposed FFL Ordnance datum. There is no OBM nearby. I am competent with a dumpy lever and able to use change points etc but don't want to pay for a topo survey if I can avoid it. I have replied with levels from existing house FFL. Link to comment Share on other sites More sharing options...
Miek Posted February 19, 2018 Share Posted February 19, 2018 1 hour ago, ProDave said: What's the height accuracy these days of the average GPS? If by average you mean on a phone or cheapish hand held GPS, then crap is the only way to describe the accuracy, especially the altitude. It can be 10's of meters out. You can of course get GPS accuracy to mm, but not cheaply. Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 19, 2018 Author Share Posted February 19, 2018 We had to have a rather complex flood risk assessment because of all the water around us, ffl is 88.35 im doing a rough site scrape and instead of removing lots of topsoil and then bringing it back in when the house is in place I wanted to be able to leave it in place in areas it won’t get in my way. Think I will just bung the surveyor a nifty and get a peg knocked in. Link to comment Share on other sites More sharing options...
dpmiller Posted February 19, 2018 Share Posted February 19, 2018 but if you're just scraping off an area to retain topsoil, why is the datum so important? Link to comment Share on other sites More sharing options...
Declan52 Posted February 19, 2018 Share Posted February 19, 2018 Have you checked your site on Google maps to get it's co ordinates and then put them in something like this site. https://www.maps.ie/coordinates.html Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 20, 2018 Author Share Posted February 20, 2018 Sorted surveyor coming this afternoon his office is only 5 mins down the road. Cheers. Link to comment Share on other sites More sharing options...
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