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How to Finish a Basement

If you’re in the process of a basement conversion and have excavated and waterproofed the area, you may be thinking about the route to completion and how that it is attained. If you’re unsure of the excavation process, you can check out our post that gives you a run-down of the process of excavating a basement.

Excavating a basement is definitely best left to the professionals, finishing it is a slightly different story as there are some areas where you can get stuck in yourself. For the excavation and waterproofing process, the risk of not doing it right is much greater than the rewards, especially when it comes to waterproofing. There are lots of pitfalls and all your hard work can be undone overnight.

We’re going to assume that you have excavated and waterproofed your basement for the purposes of this post and talk you through the steps of finishing it. We’re going to be talking walls, electrics, plumbing, flooring and will offer you some tips and advice. Don’t focus too much on the order of this post, some of these tasks can be done simultaneously but this is generally the order you should approach this in.

Framing Your Basement

Your basement should be looking pretty grey and uninviting at this point but that’s all about to change. The next step is framing the walls. There are a couple of ways to do this: build it on the floor and then lift it into place or a stud-by-stud method. Building it on the floor is quite self-explanatory, if you are undertaking this work yourself this method will be really difficult to do alone. You need precision, so you’ll need someone to hold studs into place and then to lift your frame into place which is heavy and can involve shimming.

The stud-by-stud method is easier done by yourself. Rather than building large sections of wall framing yourself, you do it bit by bit. This will be more time-consuming, and you will definitely make some mistakes if it’s your first time. We’re going to talk you through how to frame a wall:

  1. Plan. First things first, you need to line up your top and bottom plates and mark where each stud is going to go. Be accurate with your measurements and take your time.
  2. Attach your top plate to the ceiling joist. Nail it in place securely. If you’re doing this by yourself, it is worth investing in some sort of clamping solution to hold the plates in place.
  3. Using a plumb bob or something similar, mark where your bottom plate needs to go. Put your bottom plate in place but do not nail it in just yet. Mistakes can be made and if it’s nailed in it will make things harder to correct.
  4. Install your studs. Your stud should fit in between your top and bottom plate and stand up by itself. If you’re having to really force it in, it’s probably a bit too long and you’ll need to trim it down a bit.
  5. Get your spirit level and make sure your studs are straight and that they aren’t slightly bent or bowed. This will make the walls not look straight, it’s not a major issue but will be a cosmetic issue that will drive you nuts.
  6. Once you’re happy that your studs are in line with each other, are securely in place and flush, nail the bottom plate into the floor. There you have it, you’ve just framed a wall.

Electrics & Plumbing

Now that your walls are framed, you’ll have a skeleton layout of what your basement will look like, it might just be one room, or you may be creating a whole new floor to the home. This is the time to carry out any plumbing and electric jobs.

Electric – If you have a well-versed plan and some basic DIY skills you can do some of the electricity work yourself. A good portion of it is just drilling holes and making way for the wiring and cables. If you’re confident you can do that to a good standard, have a go at it. You’ll save a little bit of money in installation costs. The rest of the job requires some more skill and elbow grease. We’d recommend leaving the wiring to a professional. It’s tough work and something you don’t want to mess up.

Plumbing – If you are planning on having a bathroom or water supply in your new basement, you can also have a crack at the plumbing yourself. However, we wouldn’t recommend it. If you’re plumbing your basement, this is one of the hardest parts of the whole conversion and more expensive. There are lots of things to consider like tiling, vents, electric and probably not that much space to work with. A professional will be able to get your bathroom up and running in good time and to a great standard. A good tip is to make sure you insulate your pipes with sponge. It will contain heat and will stop condensation leaking through the walls.

Insulation & Plasterboard Installation

At this point, your basement should have all its framed walls in place and the electric and plumbing are good to go.

Insulating the walls and installing plasterboard is definitely best left to the professionals. Obviously, the walls are everywhere you look, and the insulation will make your basement habitable and cosy, so an error could be costly. This is also the part of the installation that if you make a mistake, it’s much harder to correct.

At this stage, you’ll find that a professional will be able to quote you a price that is probably cheaper than doing it yourself. A pro will be able to get their hands on the resources needed easily and at a better price than you can. This stage also requires many tools. If you don’t already have these, you will have to acquire all of them. Doing it yourself will be probably the most laborious and time-consuming part of finishing especially if you don’t have some extra pairs of hands.

If this project is your baby and you had your heart set on doing it all yourself, it may be tough to hear but turning to the pros is likely to be your quickest and cheapest option.

There are generally three methods for insulation:

  • Batts – these are large sheets of insulating material. They are cut into shape and placed between the studs, ready for the plasterboard to cover them. This is the cheapest way of doing it but the least effective.
  • Rigid Foam – More effective than batts, a purpose-built foam can be applied to the wall and attached with a strong adhesive. This will seal up more nooks and crannies, is more secure but also more expensive.
  • Spray Foam – the most effective and expensive option. Another purpose-built foam that should only be applied by professionals. Do not attempt to insulate with this by yourself as it can give off dangerous fumes and if applied incorrectly can cause structural damage. This foam can expand up to 100x, so it will be very secure and will insulate very well.

Next up is hanging the plasterboard. This can be hung vertically or horizontally but is generally done vertically. This part of the job is heavy, its dusty and there’s little margin for error. The logic of it isn’t hard, you use stud adhesive and attach the sheets of plasterboard to the studs. For all the reasons mentioned earlier, a team of pros will whizz through the work and get it done well. This method also applies to the ceiling. You can opt for a drop-ceiling as it’s cheaper but that emanates more of an office/public building look than a home.


This part of the job can obviously be easily done yourself. We’ve got some tips if you are painting the basement:

  • Get a bigger roller – Chances are you’re going to be covering a lot of surface area. Don’t settle for a standard roller and get a bigger one. You’re going to be saving money by doing this yourself so spend a little bit of that cash on a big roller, along with the right tray and roller cover and you’ll get through the job quicker.
  • Paint your trim before installation – You will make life a lot easier for yourself if you paint your door trim and skirting board before you install it. This way, you can avoid breaking out the tape and exercising caution.
  • Eye-level – Try and be eye-level with the area that you’re working on. It’s good for ensuring quality and seeing where you might need a few extra licks to even it out.
  • Use lighting – Get your hands on some spotlights and bathe the room in light. You need good visibility to see if there are any streaks that need correcting.
  • Primer is your friend – Make sure you apply an undercoat with primer. There’s a reason why it exists, it’s not a ploy from the paint companies to shake you for more money. Primer will mean you need to put less additional coats of paint on, the paint will stick to the walls better, will last longer and provides more protection. Absolute no-brainer.

Painting your basement is a good place to save some money if you don’t mind getting stuck in yourself. It’s time consuming but again don’t rush it. The painting is a big cosmetic part of the basement. It’s like the first impression and a bad paint job will be spotted immediately.

Trim & Doors

Make sure you know where your doors are going before you start framing your walls. You should have detailed plans however from before you started your conversion, so you will probably already know this. You don’t need to start making the trim for them until the walls are in the place. Think about which way they’re going to swing and where your door handle is going to be. You don’t want to get this far into the conversion and find your door won’t open fully or have any other vital issues with them.

Think about the width of your doors also. With basement conversions, there’s so many uses for them that you may be ferrying some large objects down there like beds, sofas, fridges, a pool table and so on. If you make your doors a few inches wider, you’ll find furnishing the basement much easier.

Note that wood will increase in size during the summer due to the heat. If you’re hanging the doors yourself, allow some room between the edge of the door and the door frame. It’s very tempting to get it to fit exactly in the door frame because it’s satisfying. Come summer, you’ll rue the day and will have to take them down and cut them back down to size.

For the trim, ensure your king studs are straight and true. The other studs don’t matter as much but your king studs need to be accurate. Another tip for the bottom plate is to let it go the length of the doorway during installation and then cut it out afterwards. This will make life easier for you and will ensure it’s a good fit. After this stage, you’ll be on the precipice of completion.


When it comes to flooring your basement, you really want to go for waterproof materials. There’s always a risk of leaking or flooding in basements. If this happens, you’ll regret it when you’re tearing up damp carpet. We recommend tiling, wood or laminate flooring and then furnishing it with large rugs if you want that cosier feeling underfoot.

If installing laminate flooring, you want to get some underlayment. Leave a half-inch gap between the underlayment and the walls. Once that’s all laid down, you want to lay down the laminate flooring so that the groove is facing away from the wall. Draw some straight and true chalk lines or demarcate the underlayment so you can ensure you lay them down straight. Go for laminate flooring that snaps together. If this swells during the summer, or for whatever reason, it will be easy to take apart should you have to.

Hardwood flooring follows a very similar principle but will require being nailed into the floor. Allow for the wood to expand in humid weather but exercise caution with hardwood flooring as a leak will cause some significant damage.

Again, very similar principle for tiling except you use thin set mortar to hold all the tiles in place. Tiles are a great option as they’re really easy to clean. You still have to allow for some movement due to heat. Tiling is a good option if you want some underfloor heating too, tile floors in a basement can get quite cold to the touch so is worth considering.

Cost of Finishing your Basement

How much does all this cost? Unfortunately, there is no rough estimate because your quote will depend on a variety of factors such as what you’re looking for from your conversion, how big is your existing space, how much excavation work needs doing, whether there is already a basement structure, and so on.

If you have an existing cellar structure, the cost normally sits around the £1,500 per square metre mark. If you’re excavating a new basement completely, that figure rises to £2,500. Again, this is very much a how long is a piece of string question as it completely depends on your requirements.

At Berkeley Build, we offer our services from start to finish so we can discuss how much it will cost you. Some people have basement conversions that cost over £100,000 and some for only £2,000. If you already have a basement structure, it can be really quite cost-effective, if you’re starting from scratch it will be much dearer but will also add a lot of value to the house.

So, hopefully this post has given you enough information about how to finish a basement. The basement is structurally crucial to the rest of the home so if you’re thinking of a conversion we recommend you seek professional help. Don’t hesitate to get in touch with us and we can offer some sage counsel and advice and if you choose to use us, we can oversee the process from start to finish.