A Beginner's Guide To Converting A Basement

Here's our beginner's guide to all things basement renovations!

A basement converted to a cinema room

While not a popular feature in properties built post-1960, before this, many homes in the UK were constructed with a basement or cellar sub-soil and for families living in such houses now, these are often unused. Basement conversions are becoming increasingly popular amongst homeowners in order to add to their living space without having to purchase a new property, and to add value to their existing home. 
Indeed if a property doesn’t already have a basement, the space below a home may be able to be excavated and developed: but this does form a major renovation project. No matter how you’re choosing to extend your home below ground, you’ll need plenty of information upfront on it – so here’s our beginner’s guide on all things basement!
A converted basement

Excavating A New Basement Space – Is It Feasible?

While creating a cellar or basement space in a home that doesn’t already have one may not be impossible, there are a lot of factors that can make such work into a very complicated and costly project. Professionals will need to be involved from the initial project stages and full construction plans on the initial existing structure presented. Considerations that can affect the feasibility, reality and scope of a new basement excavation include:
- The potential for drain diversion under the property
- The subfloors under the home – these are sometimes solid concrete rather than timber
- The property may be situated on difficult ground conditions such as clay, sand, marsh or made-up round
- The local water table may sit higher than expected, which will require constant pumping
- Access to the site may not be easy.
The easiest way to address whether or not a basement conversion is a reality for your home is to hire a building professional, invite them round, and show them your existing construction documents.

Calculating The Worth Of A Basement Conversion

Basements are rarely the easiest of rooms to convert into a new living or functional space, so it is important to understand that they will add a value worth the expenditure and effort. First, the estimation of the financial cost of the work versus the value it will add to the property’s resale price should be calculated (and can be done with the quick consultation of a local estate agent). After financial figures have been taken into account it is important to consider the value that the new space will add to the home life led within. If it is not equal to or much greater than the monetary and resource spend, it may be worth exploring into other avenues.

The Planning Permission Required For A Basement Conversion

A basement conversion will not always require full planning permission but legal requirements should be fully explored and understood before any work begins. If a basement already exists, the likelihood is that a change in room function will not require any permissions given – but they may be required for the installation of pipes, windows or other renovation works. For the excavation of a new basement or cellar, the local authority will be able to provide full details of the necessary building codes and zoning ordinances as well as any outright restrictions or legal regulations. Most areas will have specific fire evacuation requirements that need to be adhered to for health and safety reasons. Planning consent will be need to be applied for in most cases and is more likely to be accepted quickly if submitted by either a professional architect or a specialist basement company.
If an existing basement is currently unused but the homeowner wishes for it to be, any development will have to comply to English and Welsh building regulations in order to be legally habitable. In this case, a building inspector will need to attend and confirm that no impact will be made on either the rest of the property or to neighbour’s homes. 
A basement converted to a bedroom

Waterproofing A Basement

Existing basement spaces can be reinforced against damp with new insulation and damp-proofing measures, as well as with the installation with drains and pumps if not already in place. For new basement excavations, drainage can be installed from the initial build and waterproofing coating put in place on the interior of porous walls to create a thorough barrier against moisture. Cavity membrane drainage systems can also be explored. In England and Wales, any such products used may need to be British Board of Agrement certified and backed by insurance. 

Ventilating A Basement

Air quality can naturally be thicker and of a worse standard in basements than in rooms above ground. Ventilation is, therefore, crucial in order to provide a safe and healthy breathing environment. Keeping air flowing through allows any residual moisture in the air to dry out and can help prevent mold, mildew and fungus developing. There are also natural gases to be considered that emit from the earth with basements – so basement rooms should be regularly tested for radon and as well sealed against such harmful emissions as they are ventilated.
A basement converted into a office work space

Collaboration With Professionals

If a basement or cellar is already in place and just the function or decoration of the room is changing without any major renovation works taking place, the job may be able to be completed DIY and without the involvement of professionals. However, for projects that require any work to be carried out by builders or contractors, or for a full excavation and creation of a new cavity space, professionals will need to be hired from the initial planning stages and then throughout. There are specialist basement conversion firms that exist as well as builders, contractors and architects who specialise in sub-soil projects. All of these will be able to manage a basement renovation project from end to end as well as simply consult on the scope and/or feasibility of such a project taking place to give homeowners the ability to make an informed development and purchase decision before any time or effort is expended. 

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