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Setting out angles


Ben100

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Hi all,

 

Can anyone provide some advice on setting out angles for footings?

 

I have an unusual design with some angles, with some long runs of 10m, which is causing me lots of issues. As you can imagine if I am a degree of so off with these angles I end up being > 100mm off at the other end of the 10m run. I've just not been able to get the angles and correct lengths to match up. I have been using the 3,4,5 method for checking 90 degrees, but I'm still having issues with the other angles.

 

Do you have any advice? Maybe I can use a laser level for this, but I've not been able to find a laser level which measures angles?

 

Any and all advice is appreciated as I've spend 2 days on this already and am stuck!

 

Thanks!

Ben   

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Curves .... 

 

Measure straight to the corner you want, then measure from 2 other known points. 

 

Curves with a string line will intersect at the point you want, then check with a tape. 

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I'd never rely on setting out using set squares or similar. Best way is to use trigonometry and measuring everything from two initial known points - ideally the two front facing corners of the structure. From there there's very little  you can't set out withing a couple mm using survey tapes. It's worth sticking a drawing together and using Excel to calculate all your required hypotenuses, radii etc. Print it off and get going 

 

But as a former surveyor, I highly recommend getting a surveyor with a GPS/TS kit to set out all your points. Just give them the CAD drawing in national grid with your required setting out points and leave to it. Half days work and expect you could get a self employed surveyor do it for less than £200. All points will be setout to a couple mm. Also you can get the correct levels sorted at the same time, which is an awful lot harder with tapes and levels! On that subject, it's worth having a couple permanent trig points setout on the site that will allow to measure and level off any time you need to.

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You will need a 3 wooden pegs, string, metal tape, nails and a scale rule.

Continue with a bit of string line across the bottom wall with the green arrow to give you a line parallel to the first corner.

IMG_20190526_092343.thumb.jpg.e1e21138eee9624416f721fe5c355dd8.jpg

 

 

You then use Pythagoras to work out the small triangle. Check and check again. Drive in a peg with a nail on top.

IMG_20190526_092840.thumb.jpg.680ac8c677276f3de74f69b376028ec7.jpg

From this new corner and the inside corner use a scale rule on your plan and work out the distance to the next corner. Peg again.

IMG_20190526_092445.thumb.jpg.217086f6247e7d4494c9ff767f8650f5.jpg

Then use your scale rule and get the distance for the other corner. You will have 3 points to measure and check from now. Peg again.

IMG_20190526_093346.thumb.jpg.ec4b5cad75c47b8e959845db42209960.jpg

 

You will now have 3 pegs at the 3 corners. If you have 2 long tapes it will be quicker to check and move it slightly if needed. Go round each and check and check and check again.

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Thanks all, good advice here.

 

I’ve tried the curves method with tape, but had some issue with accuracy and spray paint. I think the lines need to be much thinner. Not sure, maybe I’m trying to be too accurate at this stage?

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8 minutes ago, Declan52 said:

You will need a 3 wooden pegs, string, metal tape, nails and a scale rule.

Continue with a bit of string line across the bottom wall with the green arrow to give you a line parallel to the first corner.

IMG_20190526_092343.thumb.jpg.e1e21138eee9624416f721fe5c355dd8.jpg

 

 

You then use Pythagoras to work out the small triangle. Check and check again. Drive in a peg with a nail on top.

IMG_20190526_092840.thumb.jpg.680ac8c677276f3de74f69b376028ec7.jpg

From this new corner and the inside corner use a scale rule on your plan and work out the distance to the next corner. Peg again.

IMG_20190526_092445.thumb.jpg.217086f6247e7d4494c9ff767f8650f5.jpg

Then use your scale rule and get the distance for the other corner. You will have 3 points to measure and check from now. Peg again.

IMG_20190526_093346.thumb.jpg.ec4b5cad75c47b8e959845db42209960.jpg

 

You will now have 3 pegs at the 3 corners. If you have 2 long tapes it will be quicker to check and move it slightly if needed. Go round each and check and check and check again.

 

Thanks for such a detailed reply! Great advice!

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5 minutes ago, Russell griffiths said:

Not sure why you are trying to do this, we had our survey co set out my place 3 separate site visits, a not straight forward building design 

cost £350 

money well spent. 

 

2 minutes ago, AnonymousBosch said:

At this stage of your build, is £200 - £300 going to make a difference? I get the DIY fun stuff. But the fact that you're posting here hints at slightly unnecessary risk 

 

Yes, good point. I’ll check with local surveyors also.

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I'm going to spend another day trying to set out the plans. If I don't get anywhere, I'll look for a surveyor.

 

One thing I've noticed regarding the drawings/plans is I get different measurements than what is listed by the architect. I'm sure there is a reason for this or something I'm missing, but I'm not sure what. If you look at the attached screen shot (capture3) of the dwg files you can see my measurements (in green) are different to the architects (in red). It looks like the architects measurements don't go all the way to the edge of the wall (capture4), which makes them shorter. Or am I measuring them from the wrong points?

 

 

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I did my own setting out for an L-shaped house compised of 3 rectangles though nothing as complex as your design.

 

In your position I would use some O level trigonometry to calculate the size of the rectangle that touches the outer edge of your difficult corners, mark out this boundary rectangle and then mark smaller boxes within the large rectangle touching each difficult corners. At this point the weird angles could be produced by joining up between the corners of inner rectangles.

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7 minutes ago, Ben100 said:

I'm going to spend another day trying to set out the plans. If I don't get anywhere, I'll look for a surveyor.

 

One thing I've noticed regarding the drawings/plans is I get different measurements than what is listed by the architect. I'm sure there is a reason for this or something I'm missing, but I'm not sure what. If you look at the attached screen shot (capture3) of the dwg files you can see my measurements (in green) are different to the architects (in red). It looks like the architects measurements don't go all the way to the edge of the wall (capture4), which makes them shorter. Or am I measuring them from the wrong points?

 

 

Capture3.JPG

Capture4.JPG

27mm is the thickness of the two lines on the page ... 

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4 minutes ago, Ben100 said:

It looks like the architects measurements don't go all the way to the edge of the wall (capture4), which makes them shorter. Or am I measuring them from the wrong points?

 

 

Hmm a 4" discrepancy on interpreting the design before any natural error tolerance in paint marks on the ground, think this has to be resolved before continuing.

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8 minutes ago, Ben100 said:

Looking at it close up, the architects lines simply don't look like they measure from the actual corner...

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That would easily explain your difficulties in setting out!

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3 minutes ago, Ben100 said:

 

Yes! I have no idea why it is like this...

 

In ACAD you call out DIMS from a chosen object in your selected later... So either he's pulling out DIMS manually or from a layer that's in behind the outermost visible layer on the drawing. But even then you'd expect the DIMS lines to pull out equally from either side of the drawing 

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1 hour ago, epsilonGreedy said:

 

Are the length errors specific to the angled walls only?

 

No, it seems to be inconsistent across the plans. Even the points at which the measuring was taken from seem inconsistent.

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I set all mine out Something I do as part of my job But I still borrowed an EDM to check everything 

After all if there are any planning issues once the house is built 

The planner will use an EDM to check your setting out 

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