Before going into details, it’s worth noting that Building Regulations approval is a different thing than planning permission. Where the latter is not mandatory, depending on the circumstances, the former is. All the work being done requires approval and is inspected by a building control officer (also known as building control surveyor or building inspector), which is sent by your local council.
What makes the price
The price for house extension drawings differ from service provider to service provider and from specialist to specialist. Different practices with the same type of specialists have different prices for the drawing up plans; an architect in Waltham Forest will probably charge different princes than one in Swansea.
Architects, as a general rule, tend to be more expensive than the architectural designers (CAD technicians) or architectural technologists, even though they do the very same thing for the most part, at least when it comes to designing house extensions. Sure, all architects will argue that the quality of their work surpasses that of the CAD technicians, but this really boils down to experience, knowledge of the laws and standards and drawing good plans in the end. The appreciation, generally speaking, is rather subjective.
Now, of course, it’s a matter of luck, too. Some architects are better than others, just like some architectural designers are better than others. It’s a fact of life.
And again, not all architectural designers will charge the same. Sometimes is a matter of experience or brand, other times it’s an economy-driven reason, such as the mere fact that your architectural designer lives in London, where rent for the office is more expensive, along with every other aspect of living in this area.
Some people believe that hiring an architect is better than hiring an architectural technologist because the former is not only accredited but also chartered or part of standards body like RIBA, and that comes with form of guarantee regarding their work. That’s not always the case. Not all architects are ARB chartered or RIBA members. What’s more, a standards body for architectural technologists exists as well, it’s called CIAT (The Chartered Institute of Architectural Technologists) and it serves the same purpose as in the case of architects.
Building regulations application
The quoted price may or may not include the price of the mandatory building regulation, but that’s something you should factor in or ask your architect / architectural designer about it. It’s usually not too expensive, but it should be considered in the final price. Some practices, like ours, offer this service for you along with planning permission application (if required), so you don’t have to worry about that.
Do you need a structural engineer?
Another thing to take into consideration, depending on your circumstances, is the price of the structural engineer’s work. In many cases, their services aren’t required, but in plenty of cases that’s necessary. Structural engineers are those people who make the calculations to ensure the structure doesn’t collapse. Like with doctors, haggling with them won’t solve anything: you simply have to follow their indications and/or recommendations. And like with doctors, these guys aren’t cheap, but absolutely necessary sometimes.
Some practices will argue that it’s better to use a chartered architect to deal with something that requires structural calculations and such, but the reality is that all these calculations must be made by an certified structural engineer.
Do you need a party wall agreement?
A party wall is a wall between two (or more) houses with different owners. When carrying works that involves such a wall (loft conversion or house extensions), you need a signed agreement from all the affected neighbours (or you can appoint a party wall surveyor to do this for you – some architects can act as surveyors). Surveyors’ rates vary between £150.00 and £200.00 per hour, according to HomeOwner’s Alliance.
One thing you can do is find out what’s the average price for house extension drawings on the local market (in your borough, for example, or London wide) and decide if the price asked by your architect or architectural designer / CAD technician is fair and within your budget. Don’t expect to do much with little money – good work should be adequately rewarded, but don’t expect to pay a boatload of money for nothing either.
You should also take into consideration unforeseen events and situations when thinking about developing a property extension. Sometimes drainage systems need to be implemented in order to start (or continue) the approved development, for example.