LSB Posted January 8, 2023 Share Posted January 8, 2023 We have just levelled some ground in our barn conversion ready to dig a foundation trench for the 'not wall', the barn has walls on 3 sides, but the 4th side was open. We know the trench must be 1m deep and we are going to do this from the base of the old floor at one end, but that is far from level in its length, it looks about 20cm difference from one end to the other so we can't use that as our guide line. As the wall is 18m long we want to make sure that the top is flat and I thought that perhaps I could use an altimeter app on my phone, but there are 100's and the one's I've looked at have no decimal places just saying 2m which isn't accurate enough. I've tried my GPS, but that feature is not on this model, I've tried the laser level, but although I can shine a laser at a consistent level I really want something I can put on a tripod / pole / spirit level at various points in the trench. As this will be filled with concrete does it have to be super accurate as long as the top of the concrete is. Google suggested Google Earth, but I can't figure out how to get the decimal places. Can anyone suggest how we do this ourselves as I don't want to get a surveyor for one trench. Link to comment Share on other sites More sharing options...
Iceverge Posted January 8, 2023 Share Posted January 8, 2023 Do you have a laser level? I did my garage with a cheap one from Lidl. Just attach it at one side of the site onto something solid that won't move. Use a story pole ( like a 3x2" stick) to take a measurement of a known height (eg the floor) and hey presto you can transfer all heights around the site. 1 Link to comment Share on other sites More sharing options...
Radian Posted January 8, 2023 Share Posted January 8, 2023 Neither altimeter or GPS are going to be any where near accurate enough. Maybe to the nearest 2m but that's about it. I don't quite understand your problem with the laser level but a water level kit might help: https://www.screwfix.com/p/water-level-kit-15m/3573v 1 1 Link to comment Share on other sites More sharing options...
LSB Posted January 8, 2023 Author Share Posted January 8, 2023 16 minutes ago, Iceverge said: Do you have a laser level? I did my garage with a cheap one from Lidl. Just attach it at one side of the site onto something solid that won't move. Use a story pole ( like a 3x2" stick) to take a measurement of a known height (eg the floor) and hey presto you can transfer all heights around the site. Hi we do have a laser level that sits on a tripod, I will try that Link to comment Share on other sites More sharing options...
nod Posted January 8, 2023 Share Posted January 8, 2023 1 hour ago, LSB said: Hi we do have a laser level that sits on a tripod, I will try that A laser with a laser receiver is quick and accurate Link to comment Share on other sites More sharing options...
TerryE Posted January 8, 2023 Share Posted January 8, 2023 IMO you can't beat a Laser Level or even a good old Dumpy. We bought a Dumpy off eBay and sold it when done a couple of years later for a net loss of just over £50 IIRC. Worth every penny. Don't get two uptight about absolute elevation. We just used a nominal datum on the public footpath outside our driveway. All that the LPA care about is relative heights for the street scene. Link to comment Share on other sites More sharing options...
LSB Posted January 8, 2023 Author Share Posted January 8, 2023 1 hour ago, TerryE said: IMO you can't beat a Laser Level or even a good old Dumpy. We bought a Dumpy off eBay and sold it when done a couple of years later for a net loss of just over £50 IIRC. Worth every penny. Don't get two uptight about absolute elevation. We just used a nominal datum on the public footpath outside our driveway. All that the LPA care about is relative heights for the street scene. What is a Dumpy, not heard of them Link to comment Share on other sites More sharing options...
SteamyTea Posted January 8, 2023 Share Posted January 8, 2023 (edited) 5 hours ago, Radian said: Neither altimeter or GPS are going to be any where near accurate enough. Maybe to the nearest 2m but that's about it Interesting, I put my GPS logger on today, drove 600 miles, parked back in my drive and the altitude gap was 2' (600mm). But I think a simple water level is the easy way for house stuff. There was a 'thing' in Google Earth were you could run the cursor over an area and it would work out the heights to quite good accuracy. Can't for the life of me remember how to do it. May have been this: View Path's Elevation Profile https://support.google.com/earth/answer/148134?hl=en I am too tired to try it now. Actually, I tried it. Dead easy, but not sure how accurate it is. Edited January 8, 2023 by SteamyTea 1 Link to comment Share on other sites More sharing options...
Radian Posted January 8, 2023 Share Posted January 8, 2023 49 minutes ago, SteamyTea said: Interesting, I put my GPS logger on today, drove 600 miles, parked back in my drive and the altitude gap was 2' (600mm). GPS suffers from Dilution Of Precision due to the changing geometry of satellites as they orbit relative to ground locations. Altitude error is generally specified as having 1.5 times the horizontal error - which itself is in the order of a few meters. Your results are surprisingly close! I'd say more down to luck than precision and accuracy was probably way off. You can do much better by measuring air pressure. Very roughly speaking, referenced to an air pressure of 1000mb at sea level, pressure falls reasonably linearly to 500mb at an altitude of 5000m (with half of the Earth's atmosphere sitting below this altitude) so pressure changes by around 0.1 mb/m. A typical digital pressure transducer is only precise to this sort of amount so you could only use one to estimate height to within 1m steps. A fancy one might improve on this by a factor of 10 but would be difficult to get repeatable measurement's from it. Link to comment Share on other sites More sharing options...
Tom Posted January 8, 2023 Share Posted January 8, 2023 https://www.groundscare-products.co.uk/mobile/ziplevel.html Forget lasers, go for one of these! I bought a second hand one in the summer and it's an incredible piece of kit. Accurate down to 0.1mm if you ever need it to be... Link to comment Share on other sites More sharing options...
TerryE Posted January 9, 2023 Share Posted January 9, 2023 21 hours ago, LSB said: What is a Dumpy, not heard of them ? Uncle Google ? You can get laser levels cheaper these days. 😊 Link to comment Share on other sites More sharing options...
Radian Posted January 9, 2023 Share Posted January 9, 2023 23 hours ago, Tom said: https://www.groundscare-products.co.uk/mobile/ziplevel.html Forget lasers, go for one of these! I bought a second hand one in the summer and it's an incredible piece of kit. Accurate down to 0.1mm if you ever need it to be... What's the working principle behind these? I'm at a loss to guess. You say accurate to 0.1mm but the picture shows a precision of 0.01mm (the width of a sheet of paper) which would be truly remarkable. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted January 10, 2023 Share Posted January 10, 2023 7 hours ago, Radian said: What's the working principle behind these? I'm at a loss to guess. You say accurate to 0.1mm but the picture shows a precision of 0.01mm (the width of a sheet of paper) which would be truly remarkable. You do wonder don't you! Link to comment Share on other sites More sharing options...
Bonner Posted January 10, 2023 Share Posted January 10, 2023 On 08/01/2023 at 20:01, LSB said: What is a Dumpy, not heard of them Theodolite, which is a challenge to spell or even say, hence the common term ... which I don’t know the origins of thinking about it ... 1 Link to comment Share on other sites More sharing options...
George Posted January 10, 2023 Share Posted January 10, 2023 Proper surveying level is best but if you do just want to check a few spot levels, then a water level is way better than any phone app: https://www.wikihow.com/Use-a-Water-Level Link to comment Share on other sites More sharing options...
markc Posted January 10, 2023 Share Posted January 10, 2023 1 hour ago, Bonner said: Theodolite, which is a challenge to spell or even say, hence the common term ... which I don’t know the origins of thinking about it ... Dumpy level is not a theodolite, dumpy is a small automatic level and theodolite is for measuring vertical and horizontal angles/setting out etc. pic here is a dumpy level. 1 Link to comment Share on other sites More sharing options...
Radian Posted January 10, 2023 Share Posted January 10, 2023 2 hours ago, MikeSharp01 said: You do wonder don't you! The fact that there's a "cable" connection between the display unit and a "cable" dispenser reel must be the giveaway. I use scare quotes around "cable" because it might not be electrical. But if its a flexible tube containing liquid or gas I can't figure out how that could work. But on the other hand, if it's an electrical link, why didn't they make it wireless and have unlimited range between the two ends? I'm beginning to think it's atmospheric air in a tube with an extremely sensitive pressure transducer at each end. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted January 10, 2023 Share Posted January 10, 2023 Found this quote on Google: but the associated link does not work. "ZIPLEVEL® is a high precision pressurized hydrostatic altimeter. It works much like an aircraft altimeter that measures the weight of the air above it except that ZIPLEVEL does not use the atmosphere to measure elevation." 1 Link to comment Share on other sites More sharing options...
Tom Posted January 10, 2023 Share Posted January 10, 2023 12 hours ago, Radian said: What's the working principle behind these? I'm at a loss to guess. You say accurate to 0.1mm but the picture shows a precision of 0.01mm (the width of a sheet of paper) which would be truly remarkable. The cable is filled with a liquid if I remember correctly. They have been around for 20+ years I think, originally made by Stanley but then bought out and renamed Ziplevel. They seem to be more popular in the US but since I've been using mine I don't know why they aren't more popular here. It really is extremely quick and easy to use. As for accuracy, rechecked the bumpf and it seems is accurate closer to 0.2mm (picture showed 0.01 inches), still not bad! Link to comment Share on other sites More sharing options...
SteamyTea Posted January 10, 2023 Share Posted January 10, 2023 1 hour ago, Tom said: As for accuracy, rechecked the bumpf and it seems is accurate closer to 0.2mm (picture showed 0.01 inches) Builders only work to an accuracy of a bricks length anyway. Link to comment Share on other sites More sharing options...
Canski Posted January 10, 2023 Share Posted January 10, 2023 17 minutes ago, SteamyTea said: Builders only work to an accuracy of a bricks length anyway. Ouch. I go down to the half. 1 Link to comment Share on other sites More sharing options...
LSB Posted January 22, 2023 Author Share Posted January 22, 2023 On 10/01/2023 at 08:28, markc said: Dumpy level is not a theodolite, dumpy is a small automatic level and theodolite is for measuring vertical and horizontal angles/setting out etc. pic here is a dumpy level. ooh, that's a nice shiny bit of kit which HID would want instantly if he saw it 1 Link to comment Share on other sites More sharing options...
LSB Posted January 22, 2023 Author Share Posted January 22, 2023 we decided to try a water level, cheap and cheerful, first one arrived, only a plastic tube and no syringes to measure. returned and another one ordered so going to try today. We know it's not level so that will be a good start as it will be easy to get more accurate. There is one patch that is quite a bit lower, we have plenty of spare soil to top up, but that will then need to be shored up for trench as it won't be solid enough. First though is persuading the dumper / digger to start in negative temperature. Link to comment Share on other sites More sharing options...
ProDave Posted January 22, 2023 Share Posted January 22, 2023 2 minutes ago, LSB said: We know it's not level so that will be a good start as it will be easy to get more accurate. There is one patch that is quite a bit lower, we have plenty of spare soil to top up, but that will then need to be shored up for trench as it won't be solid enough. You are doing that backwards. Dig the trench to the depth required, pour the foundations, build the wall and THEN fill in any low ground to build it up. Remember building up ground inside the building that will support a floor can't be done with any old spare soil, it must be inert and clean and something that will compact well in layers. Your general "spare soil" pile is only of use for landscaping outside the building. We bought in several lorry loads in inert non organic infill to build up the solum and used all the spare excavated soil to level the garden. 1 Link to comment Share on other sites More sharing options...
LSB Posted January 22, 2023 Author Share Posted January 22, 2023 thank ProDave, but the complication here is that HID want to use concrete rather than blocks to fill the trench so he doesn't have to lay foundation blocks under the ground. Thinking about it, the lower ground isn't that much difference to the rest that it will affect deep concrete. Thanks for the advice. Link to comment Share on other sites More sharing options...
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