We are often asked how much it would cost to create a basement floor to an existing property. The unhelpful answer is that this is totally dependent on what you intend to put in it, and to what extent it lies underneath the existing structure.
Pushed to give a guide price, we normally state that the cost is between £150 and £300 per sq. ft. of area per basement floor. That doesn’t really help when you are trying to make that decision to appoint an architect to proceed with the job. You need to know a much closer figure, or you will either kill the job with caution, or jump in with no safety net. To help you we have the following handy hints:
1. Step one is to phone us up, or send us an email. Our engineer and estimator will pop round to see you to discuss what is feasible, and give you a very good approximation of price. There is no obligation from this, but it will help you take the next step with confidence, even if that step is to stop.
2. Consider whether you can use adjacent land as your basement, instead of the footprint of the property. For a house this may mean excavating out the back garden, putting in a basement and then topping off with a slab after which you can re-create your original back garden, or start afresh with glazed views into your new basement.
3. Think about what you would like to put in the basement. We are frequently asked to install swimming pools, gymnasiums, cinemas, saunas, spas, garden rooms (glazed fourth wall), games rooms etc. Just occasionally we are asked to install servant’s quarters or utility rooms. The guide here is to consider the value being added to your property if your main purpose is to enhance investment value.
4. There are many ways to bring light into the basement, so consider this as secondary to your access point. How will the basement interact with the rest of the property? Is there room to extend your existing stairwell downwards? There is always a solution, but we can help you to get there quicker.
5. Are you intending to remain on site during the creation of the basement? This is quite often feasible, but it does have implications. For example, you will experience regular periods of noise, which will transmit through the structure to all parts of the property. Furthermore - if we are undertaking a whole house renovation - the phasing of work to allow for partial occupation will mean a longer construction period.
6. Importantly, make sure whoever you use is willing to provide you with an insurance backed long term warranty, such as that provided by members of the Association of Specialist Underpinners (ASUC) or similar. There are a lot of companies selling a service out there. Very few of them have the experience, resource and capability needed to become ASUC members. A warranty is worth very little unless it still exists whether the installer is trading or not. Remember, it may be a considerable investment you are committing to. You need the comfort of a good warranty.
7. As costs go we may not be the cheapest, but we will be close to the cheapest. Furthermore, we will be the best, and that has got to count!
Tags: Archer-Hoblin, basement retrofit, basements, cellars, excavation, underpinning