G1 Gauge

124,90 w/o VAT per box 10 units

  • For parallel lip cracks inside and outside
  • Reading the crack with a resolution of 1/10th of a mm.
    Easier to read: the G1+ gauge
  • Automatic reading and monitoring of measurements with Saugnac.app
  • Simple fixing with self-adhesives supplied or mechanical fixing with pre-drilled holes
  • Can be fixed at an angle with the folding bar supplied
  • Supplied in boxes of 10 gauges with 1 pen and instructions for use

Made in France

Technical characteristics

  • Resolution
    0,1 mm
  • Type of monitoring
    Tracking on 1 axis
  • Type of crack
    Vertical, horizontal and corner cracks with the folding bar
  • Use
    Indoor / Outdoor: weatherproof and UV resistant
  • Fixing
    Gluing with the self-adhesives supplied or mechanical fixing with impact anchors (sold separately)
  • Installation conditions with self-adhesive
    Installation temperature: between -10°C and 35°C. Effective bonding from -40°C to +80°C
  • Length
    160mm with folding bar
  • Width
  • Thickness
    3mm (plate thickness = 0.7mm, pull tab thickness 0.5mm)
  • Maximum amplitude
    approx. 20mm (possible variation between maximum and minimum measurement)
  • Weight
  • Material
    Impact calendered PVC with UV stabiliser
  • Coefficient of linear expansion
    7.10-5 m/m/°C

How to fix the gauge?

In order to most effectively measure the evolution of the crack, the gauge is usually fixed at the widest point of the crack or in the middle of the crack. The G1 gauge is made of a material that is flexible enough to accommodate and follow the movement of irregular, convex or concave surfaces.

There are two possible methods of fixing:

  • By gluing: the fixing is ensured in a simple and fast way by double-sided self-adhesives supplied. The surface must be in good condition (it must not crumble), it must be relatively smooth so that the sticker can be stuck to the entire surface, it must be clean (free of dust and grease) and it must be dry.
    If necessary, and especially if the surface is not completely flat and has roughness, it is possible to reinforce the bonding with a fast-curing epoxy adhesive in a biseringue.
  • Mechanical fixing: G1 gauges are supplied with 2 holes of Ø 4 mm. These holes facilitate mechanical fastening by means of a impact anchors. The 4mm diameter makes it very easy to make the hole on any support.
    The impact anchor = Ø 4 mm : it is therefore sufficient to make 2 holes of Ø 4 mm, to place the impact anchor in the hole of the gauge and the folding bar, and to give a light hammer blow to fix the whole.
    On difficult substrates (crumbling, dusty, rough, damp), we recommend using impact anchors to prevent peeling off. Packs of 50 impact anchors are available or a complete ready-to-use impact anchors kit is available with a 4mm drill bit, a screwdriver and 30 impact anchors.

A: tap-screws / knock-in dowels
B: Hole ∅4 in the strip
C: Hole ∅4 in bracket

Result of fixing with anchors and screws:

G1 Gauge fixed with impact anchors

Installation tips

Ideally, position the vernier triangle between 10 and 11 with the two speckled bands appearing on the right and left. The objective is to centre the pull tab. Do not try to position the vernier triangle on the 0. This is useless and very difficult to achieve. Indeed the principle consists in measuring the difference between 2 measurements: it does not matter the value of the first measurement, it is it which will constitute the 0 point.



Position the pin of the folding bar in the middle of the slotted hold to absorb any movement.
This patented system avoids straining the gauge by blocking the pull tab if there is also Y-axis movement.
However, this gauge does not measure Y-axis movement, so a G6 gauge must be used to measure movement on two axes of the plane.

How to measure crack in angle?

The G1 family of gauges is supplied with a folding bar that allows for corner mounting.

G1 crack gauge fixed in angle

The internal corner is a 90° angle. A G1 gauge is used with a plastic angle bar

There are some irregularities in the plucking. Installation of a G1 gauge with the included folding bar and a intermediate plate (sold separately)

A G1 gauge is used in an internal vertical corner with an aluminium angle bar fixed with a plug and screw

G1 fixed in angle

A G1 gauge is used on a crack on the edge of an external corner with an aluminium angle bar

How to protect the gauge?

We recommend that gauges used in public places (schools, shops, streets) should be protected.
The protective cover can also be fixed with plugs and screws. Two types of protection are available: standard protection et high protection anti-UV.

Protection for G1 gauge


How to read the gauge?

The upper section is graduated in mm from 0 to 30: this is the measurement scale.

The lower section moves: this is the 1/10th mm vernier (10 divisions of the vernier correspond to 9 mm on the measurement scale).

Reading a measurement with a decimal
a) Reading the millimeters:
The pointer of the vernier is between two graduations of the measurement scale. Example: between 13 and 14. The number of mm corresponds to the graduation to the left of the pointer of the vernier: in this case that is 13.
b) Reading the decimal:
Find the line on the vernier which is exactly aligned to a line on the measurement scale. In this example with gauge N°3, graduation 8 on the vernier is in line with graduation 21 on the measurement scale. The decimal reading is thus 8/10th of a mm.
The overall reading is therefore 13,8  mm.
Even simpler to read and more accurate:    G1+ gauge with “digital” readout.

Download the Saugnac.app application to monitor your measurements

The Saugnac web application, which is completely free of charge and has no limitations, is available on PC or smartphone from https://saugnac.app. It allows you to :

– Identify each gauge and its measurements with its unique QR code
Automatically read the measurements of the G1, G1.1 and G1.2 gauges
– Save the measurements in your space
– Retrieve the temperature and the humidity rate thanks to the geolocation
– Calculate the measurements with the expansion according to the temperature
Collaborate with several people on the same gauge
– Manage alert thresholds
– Classify gauges by location and locate them on a map
Download data in Excel format
– Automatically display graphs
Share data with others without an account
– Access the application from your PC or smartphone
– Add measurements without a connection in offline mode

Find all the explanations on how the application works

Download monitoring Excel file

In order to facilitate the monitoring of the evolution of the cracks, you can download the Excel file for monitoring the G1 measurements

This Excel file is very easy to use: you just have to duplicate a sheet for each site or construction site observed with the possibility to follow up to 10 gauges.
This file takes into account the coefficient of expansion of the gauge by adjusting each measurement taken with the temperature compared to the initial temperature of the 1st measurement. If you have not taken a temperature reading, simply leave it blank and the coefficient of expansion will not be taken into account.

Note that the impact of the expansion coefficient on the G1 gauge measurement is very small (about 9 micrometers every 1°C).

Here is an example of the type of monitoring obtained with the file:

Related Products

You may also like…