Tolerance & As-Built Surveys

As-Built Surveys can be perfomed throughout the construction phase of a project to provide an important insight into the current progress of the project and to verify positional accuracy of the various building and external elements.

This information can prove to be invaluable to Project Managers / Design Teams and the like, when it comes to working pro-actively during the construction phase. Errors can be picked up sooner and solutions found before the issue negatively impacts the programme.

As-Built Surveys perfomed at the completion of a project provide an all important record of the final position of a buildings elements and external works.

This can be particularly helpful, if for instance, there will be alterations later on in the buildings lifecycle. A common example, manholes have had to be repositioned from the original layout drawing.

An up to date As-Built Survey Drawing will help the drainage engineers to locate and identify manholes easily and quickly in the event of a blockage or somesuch.

The same can be said for services. Picking up the actual positions and depths of mains Gas, Water, Electric, BT, CATV etc. up on an As-Built Survey during construction can save huge amounts of time and effort down the line should they need to be relocated.

Especially useful on housing developments where connections to service mains are made as the project progresses and the mains have sometimes already been backfilled.

As-Built Tolerance Surveys are used to compare the As-Built surveyed position of a building's elements or external works, against the designed position of the building's elements or external works.

An example may be the As-Built levels of a floor slab. We would conduct an As-Built floor slab level survey and compare this against the designed levels given for the slab. Using the DTM's for both surveyed and designed, we can create a graphical representation of the differences to enable an "at-a-glance" view of the high & low points of the slab.

If you have been specified a design tolerance for the floor slab, +/- 15mm for example, we can graphically represent areas that are within tolerance and those areas higher or lower than the tolerance given.

Another example could be foundation pile positions. We would conduct an As-Built piling survey after piling was complete. We can then compare the surveyed pile positions against the designed positions and / or specified tolerances and give a direction and measurement value of any difference between the two.

We can also compare the pile top level in relation to say the specified cut-off level, to enable the calculation of how much linear metre of pile needs cropping of cutting down.