Ten things to consider when commissioning a measured survey
Every architectural project that involves an existing building needs to have a measured survey before the design team can start working on it, but what do clients and their representatives need to consider when commissioning the survey? One of the reasons we started doing surveys in-house was the disconnect between what we asked for from a survey and what we received. In order to get the optimal result, it is vital that the surveyor has a complete understanding of what the client is looking for from their survey from the outset. So what are the things to consider? LA Surveys are here to help.
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Measured surveys provide the foundations on which proposed architectural drawings are built, so it is crucial that the design team have an accurate and relevant set of survey drawings to work from. The best way to achieve this is to have an early consultation with your surveyor not only to discuss the existing building but also the proposed scheme. By having a full understanding of what you are looking to achieve, your survey team will be armed with the knowledge and foresight they will need in order to capture all of the relevant information.
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Time on site is costly, hence ensuring your surveyor only spends time scanning and measuring the relevant areas can save time and costs for all parties. Where appropriate, adjacent areas can either be supplemented using existing drawings (for example from previous planning applications) or can be scanned at a lower level of detail and accuracy to speed up the process. As above, start by consulting with your design team to prepare a focused and coordinated brief.
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This should go without saying. The reason most clients want a measured survey is to guarantee that their design team has accurate information to work from. A good tolerance for accuracy is +/- 25mm for existing buildings. It might be that you can relax that for some elements, which will speed up the on-site process.
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Some survey companies are able to provide a link with panoramic photos and the 3D point cloud data to be viewed in the same space, which is really helpful for us when building the model but also a great reference tool for anyone. You can navigate through the model like a virtual tool. Panoramic JPEG files can also be shared.
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It is important that your survey quote outlines every drawing that will be delivered as well as the scope of the survey. Sometimes part of the neighbour’s facade is needed to provide context in planning drawings. Make sure that you will receive the appropriate type and quantity of plans, elevations and sections. These should be discussed during the consultation meeting.
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This is relevant not only to your surveyor but also to your wider design team. The construction industry is constantly evolving its methods of working to mitigate clashes on site, which can prove to be extremely costly. BIM is now recognised as the future of construction: all consultants share a model that, among many other things, can help avoid clashes. Your survey company should be able to offer a BIM model as part of their services. While it might come at an added cost the long term benefits often dwarf the investment. Because building a BIM model is the most efficient way for us to generate survey drawings, LA Surveys’ BIM models carry little premium over traditional 2D-only drawings. In fact, if we are retained as Architect for the project, we will build the survey BIM model for free!
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The survey quote should also detail the surveyor’s delivery timeline, including start dates and, crucially, a deadline for issuing all deliverables. For a large building, this is not a short process so it is important to commission your surveys well in advance to ensure project milestones are not missed.
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Information is money, but it can also cost a lot of money if the information is wrong. Remember, cheaper is rarely better. In terms of survey information, the deciding factors should be the quality of the information and its accuracy, followed lastly by cost. This will give you the optimum value. The key is to ensure your surveyors have a clear understanding of what the survey will be used for so they can tailor their approach to precisely that. An appreciation of construction methods is invaluable too. That’s why using an Architect to do your measured survey adds huge amounts of value to it.
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Architectural companies have a wide range of preferences when it comes to the software they use. Therefore it is vital that your survey drawings (and BIM model) are compatible with the software that your designers are familiar with. Compatibility issues can be frustrating and time-consuming, and can often lead to misleading discrepancies in accuracy. An early discussion during your consultation can be vital to iron out these creases.
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Are all areas of the building accessible? Often areas in surveys are missed because appropriate access has not been arranged in advance of the on-site scanning. This typically includes roofs, attics and lightwells, but also locked cupboards, etc can lead to the dreaded “not available to be surveyed” note on the survey drawings, which is never helpful.