For my day job recently I have been carrying out a lot of measured surveys – measuring buildings and drawing up the plans, elevations and sections. This is something that we touched on briefly during my course at unit but now a few years down the line and with a fair few surveys under my belt I thought I’d share what I’ve learnt with you.
Firstly there are a few essential items you need when you carry out a measured survey.
I tend to use an A3 sized clipboard if it is a large building, and a smaller A4 if it is a small building. Use what works best for you, obviously the larger paper you use, the easier it will be to get all your measurements down without getting into a total mess.
Lots of paper!! Don’t underestimate how much paper you might need. Sometimes you may draw a general layout, but need another few pages for things like column positions, elevations, services etc
Pens and Pencils
I always make sure I have a good selection of pens and pencils on a survey. I have started using one of those three colour pens now which is really helpful – more on that later.
In an ideal world you need to get yourself a laser measure. I don’t know how I would have done half of my surveys without one. They are super simple to use and really accurate. They save so much time as well.
Don’t forget spare batteries too!
Sometimes you just need an old fashioned tape measure. Moreover, if you don’t have a laser measure then you will need to make sure you have all sorts of suitable tape measure equipment.
Totally invaluable for a site survey – make sure you have a reasonable camera with full charge.
Depending on the site, you may need your hard hat, high visibility jacket and site boots.
Before the survey:
Before even going to site, try and find out as much about the building as you can. Check out google maps to get an idea of shape, orientation, street view etc. In some cases you can almost sketch out the building before you even arrive on site. Its nice to arrive to do a survey with a bit of familiarity.
It is also important to know why you are measuring the building, as this will determine how detailed your final drawings will need to be. Are you only required to draw plans? Or will you need elevations and sections? Is the drawing for internal renovations, external extension? Is it for planning permission, construction? Will you require visuals? If so good photographs will be important.
The first thing I do when I arrive I site to do a measured survey is have a look around the entire building first, so you can get a feel for the layout, where the rooms are, stairwells, etc. This is helpful for when you start to draw out the building.
Depending on the size of the building you are surveying, you may want to break it up into sections, so each page you have a section, so that you can draw it out at a large enough scale to add your measurements/dimensions. You can either draw each section as you go – draw, measure, next area, draw, measure, next area etc. Or you can draw out the whole building then go round and take your measurements. Whatever works for you.
If you only have a tape measure, it is usually best if there are two of you, but you can do it alone, it will just take a bit longer. With a laser however, it is pretty easy to get everything measured alone.
I don’t tend to draw a huge amount of detail as generally it doesn’t really add anything. Here are a few of my drawings. Not the neatest in the world, but I can generally make sense of them!
A tip on drawing, I use a three colour pen to draw out my surveys. I use one colour for general drawing and measurements, then another colour for window details (cill height, head height), and finally another colour for all heights and levels – ceiling heights, floor levels, steps etc. This is really useful when you are back at your desk trying to figure out what the random numbers are floating around on your drawing.
Start your measuring in one corner of the room and work your way around in a clockwise/anticlockwise direction. This way you won’t miss anything. It is also wise to take a few diagonal measurements to help with accuracy.
Take your measurements at a height where you will pick up the features like windows and doors. It is helpful to take running measurements, along with a full measurement of each wall. Running dimensions mean that there is less chance of making mistakes. It may be more time consuming on site, but I always try and take as many measurements as possible, I would rather spend an extra hour on site doing this, than having to go back again the next day when I realise I have missed vital dimensions.
Don’t forget to measure ceiling heights, and if possible pick up the floor thickness (usually possible to do in a stair area), which will help with elevations and sections. Make a note of wall thicknesses, which will vary internally and externally.
Finding roof heights and details can be difficult and is very dependent on the building. Here are a few tips on how to measure the roof height. If possible it is best to have a disto/laser measure when taking dimensions for roofs.
Externally, try to take a floor to underside of eaves measurement. In addition to this, if the building has a gable, try to take a floor to underside of ridge measurement too. This can be hard in daylight with the laser, but persevere!
Next, if the building is brick built or has a uniform facade (regular stonework, blockwork etc), take flat good photographs, and use these to count bricks/block and then work out distances from there.
Internally, make sure you are thorough with your floor to floor, floor to ceiling measurements. If you can gain loft access this is ideal – you can then get underside of ridge measurement from the top of the ceiling joists, and take measurements of the rafters etc. With this information you will be able to work out the approximate height of the roof, and consequently the angle.
Hipped roofs are more tricky, but often come together when you have floor areas, eaves heights and internal measurements from the loft access.
Usually after measuring either a room/area I then photograph the entire room – focusing on any difficult or complicated areas. I tend to take far too many photos but I’m sure it pays off. It is always a great help when you are back at your desk trying to draw up the scribbles!
Sketch out the elevations and measure key features to help you. If you are using a laser measure, try and measure the eaves and if possible ridge height. If the ground level varies, take a constant feature on the elevations, for example a window cill, and measure to the ground from this point around the building. This will show the changes in ground level. Most of your elevations will be possible to draw from the floor plan, but pick up any features that are external only. Again, take loads more photographs.
One method we use to measure angles of strange shaped buildings is triangulation.
The image above shows how to carry out this method. Pick a point on one wall (A) and measure to the corner. Pick a point on the second wall (B) and measure to the corner. Finally, measure the distance between the two points on the wall (C). This will give you the measurements of all three sides of the triangle. From this you can either work out the angles, or draw it up in cad more easily.
- Ceiling heights
- Structural – beams and columns
- Floor levels
- Steps – changes in levels
- Door heights
- Window cill heights and window head heights
- Rainwater pipes
- Foul drainage pipes