Guidelines for Basement Regulations

Author: Natalie Martin

Why Building Regulations Exist

Building regulations are there to protect yourself and your building work so it is important that you follow them. Your builder should be well informed of the regulations for your basement conversion and they will have to answer to the building inspector who will inspect their work and makes sure that they have followed the guidelines and done everything by the book and make sure you have planning permission.

There are a number of potential problems that could arise with your basement conversion, building regulations will make sure that your basement conversion is not falling short of any regulations. Before work can commence on your basement conversion you will need to submit your plans in full to your local council for planning permission where they will asses them along with an engineer. It is important to keep the building inspector on side, so inform them of your development every step of the way.

Basement Waterproofing

Building regulations for cellars and basements state that all floors and walls that are below ground level need to be waterproofed. This is to prevent damp and water entering the structure of your conversion and reaching the rest of your house.

You will also need to consider how much water is getting into your basement, you will need to get a structural engineer to assess the height of your water table, which is how far you need to dig down before you find water.

You will need to get British Board of Agreement accreditation for whichever method of waterproofing you choose for your basement renovation and you will need to get certificates to prove this.

Your Basement Structure

To make basements or cellars inhabitable and to comply with building regulations, your walls may have to be underpinned and the floor dug into further in order to achieve more room, because of this you may need to add more support to your joists such as steel beams.

Any structural work you carry out to your basement room will also need to be passed by the inspector to make sure that it does not impact on the rest of your house or your neighbour’s house and that it can support your proposed plans.

Fire Escapes

Your basement room normally only has one access point in and out of the room. If you are planning to use the basement you will need to provide another means of escape in case of a fire and your staircase is blocked.

Your fire escape can be in the form of a window or another door, as long as you can show that in an emergency there is another way to get out of the basement.

You will also need to have adequate ventilation in your basement conversion to allow air into the conversion which will help prevent any damp and moisture forming.

Insulation

You will need to adequately insulate your external floors and walls as well as your windows. This is not only part of building regulations but is also help keep your basement renovation energy efficient. You will need to make sure that they are of an adequate thickness. Your local council and builder should be able to advise you as to what thickness will be suitable.

Electrics in Your Basement Conversion

Any new electrics that are installed in your basement conversion must comply with building regulations. You will need to get all electrical work installed by a registered electrician and you will need to get certificates to prove this. The certificates will not only keep the building inspector happy but they will also look good when you come to sell your house in the future.

Different councils can ask different things of you when it comes to your basement conversion, so it is important that you speak to them before you plan or start any of your work. Building regulations are there to protect you, so it is important that you don’t ignore them and work with a qualified builder who knows the regulations inside out.

20 Comments (of 22)

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DSteele 29 Jul 2024

Regarding my place of work, the property includes basement level offices with a fire escape door into the external basement area with steps up to pavement level. Wrought iron fencing is in place at pavement level. Can we place a cover over the steps, fitted at pavement level, which would have an accessible section openable from the inside to maintain the escape route? The reason is for security, to prevent persons accessing the basement atrium area out side of working hours. If this is allowed, is planning permission needed? Thank-you.

Mark 5 Nov 2023

Does anyone know if there are any regulations covering the use of timber stairs in basments

Kitkat 30 Jul 2023

My friend and her 2 year old son have been put in a basement for emergency housing. It has no windows and only means of escape is the front door. Is this legal?

Betty Stoggs 5 Feb 2021

We have a dormer bungalow with stairs rising from the dining room to a landing off which there are 2 bedrooms. The stairs have a supporting wall on one side and are railings to the dining room on the other. Beneath part of the house is a basement which has 2 rooms and a bathroom. Both main rooms have a window and an external door. The basement currently cannot be accessed internally from the main house. We want to put an internal flight of stairs to connect the the two. Unfortunatetly the staircase to the basement cannot run exactly below the current staircase as the supporting wall in the basement is thicker than the supporting wall the staircase is against. Therefore were wondering about running the stairs at right angles to one another. However we are uncertain about the fire regulations - do the two flights of stairs have to be separately boxed in from one another or can we have 2 'open' staircases at right angle to one considering there are 2 external doors in the basement and 3 on the level above? Any advice welcome

CVD 10 Dec 2020

Hi, currently we have a void under our house and we would like to create a new basement. Egress is a bit of an issue. How can we make sure it complies to be a non-habitable room like a utility or wine cellar? Is there a limit for size or is there any guidance on what we can do with finishes so it is not a habitable room.

Sazo 16 Jan 2020

Hi, if we change access door to cellar by 90degree (in the case to under main stair case) are there regulations to the size of the new door and surface area /width of first step? The cellar is just used for storage Moving the door would mean that the steps are side on to the access door. Thanks.

Juan 4 Dec 2019

Hello, I own and end of terrace property in SE7 (London) which has a basement in great conditions (tanked, no dump, etc..) and with good dimensions (around 20sqm). The only problem is that it hasn't a egress window and it's height it's 2m. I have two questions: - There's the possibility to open a door into the bathroom annexed to it which already has a window to the backgarden. Would be the window still required or would it work a door as a fire escape in this case? - In case we had to go for opening a new window, where can I find the required characteristics of an eventual egress window in case we could place one. - Is there any specific minimum no be matched in terms of height? I was told that for new spaces minimum is around 2,30 however in our case it wouldn't be a new space since the basement already exists. The reason for asking these three points is that we'd like the basement to not being a basement anymore towards the deeds but a livable bedroom so we gain more square metres legally. Many Thanks, Juan

Heath 19 Aug 2019

Some advice please Hi l recently purchased an old Victorian house with a cellar, l want to convert it to a living room. It has plenty of head height and l understand l need to have a separate escape route and l intend to use the old coal Shute for this. The coal Shute was open for a number of years and the cellar has become damp as it was open to the elements, l have now closed this off and l’ve put a dehumidifier down there and all the internal brick walls are drying out nicely but the back wall (which is stone) it seems to be damp all the time ! 1, I’ve been told l Should dig down on the out side and line it, treat it in someway! 2, then to use a cement that has the additive to make it water proof for the floor and a similar product on the walls 3, what depth/thickness should my cellar floor be

Monkey 5 May 2019

Hello. We have a self contained basement flat that we want to rent out. It has 1 bedroom at the back with a window that only opens a little (about 20cm) and a living room/kitchen at the front, with a front door at the end of the hall way. By law, does that back window need to open fully? ie, is it still classed as a fire escape if the window doesn't completely open? And is it compulsory to have 2 fire exits in a basement flat? Thank you

Lauren 21 Nov 2018

Hi, we are purchasing a basement flat and are receiving conflicting information regarding fire exits and would like some clarity. The flat is a split level, upside down, basement conversion - ie you enter the living & kitchen space on the ground floor, and go downstairs to the three bedrooms. Two of the bedrooms have access to the outside lower ground via doors. We have been advised a fire escape is required to the ground level allowing an alternative means of escape should the staircase be blocked as mentioned above. The seller believes as they provide a fire escape via the back bedroom to the garden this fits the regulations. HOWEVER our surveyor believes because there is effectively no means of escape from the garden itself (no gate or access beyond the house) a second fire escape is required via the front bedroom leading to the street and therefore distancing ourselves from the property, which would not be possible via the back unless we jumped the fence (I'm not sure what implications that would have should there be an elderly or disabled resident in the property, etc). Please can you advise? Many thanks

williamro 10 Nov 2018

I have a damp cellar used only for storage. The existing access is via a concrete staircase installed when the house was built in 1955. Due to proposed alterations at ground floor level this staircase will no longer be usable and I wish to construct a trapdoor with new stairs or possible reuse of old stairs. The Building Inspector has said that the new stairs must comply with Building Regs and the trapdoor be surrounded by guarding of 900 mm height. There is no room to provide these. My question is do full building regulations apply to this work to an existing non-habitable cellar.

Stuw 20 Oct 2018

Good afternoon, i am looking into converting my basement, its a huge space made up of three rooms(separated by supporting walls), I am aware of some of the regulations like fire plaster board for the ceiling and damp coarse. how ever the fire escape routes, as it is three separate rooms and only one has a window up to the back garden does this mean i can only utilise that one room? or is it one escape route for all three rooms?

LoftsAndBasements Editor 31 Jan 2018

Sorry we can't visualize this, your local building control officer will give you advice (for free)

... 30 Jan 2018

my house is victorian. has a ground and first floor. The basement was originally for coal storage no access inside house only exterior. It is not a usable space currently. not intending to change that. bulk head access with no door, access is by small wood barn type door at bottom of steps. walls and floor are soft victorian brick. ceiling is plaster board covered floor joists. Do building Regs apply to my cellar door , am I required to make any changes to it? Thank you

LoftsAndBasements Editor 30 Jun 2017

You should really consult your local planning and building control departments about this as we can't comment on specific cases where we don't have all the information.

Zakariya 29 Jun 2017

Hi I would like to know if I have small window in my basement, which by the way is underground and the small window is on the pavement outside can I rent out my basement there is a ventilation vent also kitchen bathroom bedroom separate gas and electricity meters, it's also registered as a basement flat with Lambeth council. Just only one fire exit . Can I change the window into one that can open up ? Also my basement always seems to have that dampening smell although you can't see any damp what so ever. Can you recommend any powerful vents silent ones please. Many thanks

LondonRes 1 Jun 2017

Hi, I live in a multi-story (five Floor) apartment with a an underground car park. An issue recently raised with the Freeholder was that there where No Fire escapes in the basement car park. There are two lift shafts with stairwells as well as the main ramp up to the ground level however these are all gated and access controlled with no means to open them without a coded key. There is no means to escape or utilize these points of exit if you do not have a coded key. Is this legal? Should there not be a quick release on the stair well doors to allow you to exit should you not have your keys on you? Thanks in advance.

LoftsAndBasements Editor 7 Apr 2017

It's pretty unlikely this would be allowed. Depending on how long ago the conversion was done, all new builds and conversions/moderations require a means of escape or additional fire resistance measure. Check with your council if you're unsure about this.

London Sw13 1 Apr 2017

I recently went to see a room, as need a new place to move in. I saw place being advertised as a single room. Made an appointment to see the place, and was shocked to see a room being in the basement of a house, with another 3 rooms, and there are another two floors above the basement room in question. The single room in basement got no windows, just some sort of ventilation. My question is, is it legal to rent a room, based in the basement of a house, no windows and only one point of excape in case of emergency. Thank you.

LoftsAndBasements Editor 10 Jan 2017

Is this for residential use or is the building converted into flats/apartments?For a residential property a fire door might be required between storeys (but not on every door) if there are three or more storeys. If the above floors are open plan, then more fire doors/fire supression methods will be required. You might want to get a second opinion on this from a professional (a private building control officer or one from another authority).

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