Thank you. I suspect it will have been part of a small development of houses from what you say. This doesn't change the legal position of what I am about to say bt the reason I ask is that situations such as the one you describe tend to occur more commonly where one developer has developed a number of houses together on a small large development because of the time of developing the houses, the developer will own all of the land which is to be developed and they tend to run utility conduits along routes which are the cheapest to lay cables where cost is usually proportional to length of cable and pipe.
the best practice is for such cables and conduits to be laid under roads serving properties but economics mean that this doesn't always happen when a developer can save money by laying over a shorter or more expedient distance.
situations such as the one you describe are frustrating at the least and can result in some not insignificant additional costs or at worst can prejudice an build of an extension. However usually they can be dealt with.
it is not always necessary to move the infrastructure conduits in order to construct your extension. It will depend upon how deep your footings are to go and how deep the pipes and cables are laid. It is a particular aggravation that you have found not just one pipe or cable but potentially three different kinds. The reason for this is because the first step before you proceed any further is to contact your local distributor for each service in order to ascertain whether they will require the cable or pipe to be moved or whether they are content for you to build over the pipe or cable with a build over agreement - this is an agreement which provides along the lines that the you will afford acces to the utility provider to your property in the event that they require access to maintenance purposes.
because the at least three different kinds of infrastructure conduit, you will need to contact each utlity provider in turn to agree with them what does or does not need to happen. you can find your local distributor operators using the following link (note this is not the same as the company that supplies your energy bill):
regarding a specific question you are course correct thatthe cables and pipes should ideally not be laid under your garden and should where possible be laid under roads. However there is no legal requirement that this is the case and developers often take literal short cuts so as to enable them to lay conduits over shorter distances and save money. They are required to disclose the location of pipes and cables to the original purchaser. In addition, for subsequent purchases, your conveyancing solicitor should make enquiries as to the root of pipes and cables from the seller but the seller will not always know the exact route of pipes and cables and whether this is the case, your conveyancing solicitor need not make further enquiries unless you instruct him to. It is possible to carry out pipe and cable service as a buyer but these will cost money and so most buyers elect not to instruct such surveys unless they are buying property specifically with development in mind.
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