Bathroom Installation Costs

How much does fitting a new bathroom cost?

A question asked by all potential customers when facing the prospect of renovating their bathroom is how much does it cost to install a bathroom? You can read the articles from search engine results for the same question mainly written by sales representatives for big companies most of whom have no experience installing a bathroom and yet are apparent experts at the associated costs. There are of course the additional costs that come with other items such as niches or cubby holes, or moving a toilet for example. However as a fitter I have also come up against many different scenarios fitting bathrooms that have required additional work. These issues often cannot be seen and taken into account at the quotation stage until the existing bathroom has been removed to reveal any of these potential issues. Additional costs can be agreed to a certain extent if assumptions are made that some of these issues will be found but not always. In an ideal world these issues would not occur and the bathroom renovation would be a straight forward rip out and replace and so the price quoted is what you will pay. So for all potential customers the following article has been written to give you an idea of the most common issues we encounter installing bathrooms that often result in the costs escalating.


By far the single most common problem that leads to the cost of a bathroom installation rising. It is a bigger problem in homes with timber stud walls and timber floors than brick walls and timber floors. If you are in luck then only the timber floor is rotten and replacement of that is often straight forward and may have already been priced into the quote since the job required that work anyway. This is nearly always the case with a chipboard floor under a bath. Sometimes the extent of the water damage to the entire bathroom floor is so bad that it’s entire replacement is necessary. We often find that urine damage to chipboard floors around toilets requires the floor replacing. It would be nice if it turned out that once the subfloor is up that there were joists or other timber braces between the joists commonly called noggins or dwangs already in place all around the existing perimeter of the bathroom where the floor meets the existing stud walls. There never is. This requires additional joinery work to install timber where necessary in order to support the edges of the new floor boards. They cannot simply be installed and the edges left floating between joists, they simply will not take the weight of items such as toilets etc.

If you’re unlucky one of more of the stud walls are rotten and in need of replacement. A straight forward non load bearing stud wall replacement is not a great issue but will often require an additional days labour for the removal and renewal of the wall as well as the cost of the additional timber. That is just for the joinery work. Then the wall on the bedroom or hallway side will need new plasterboard and plastering. The plaster then needs painting and the installation of new skirting. That is a few days extra work in total for straightforward replacement. This was all necessary on the job shown in photo 1. The chipboard was black with rot. The base of stud walls were rotten and crumbing in our fingers. They had to come out. We would not have continued the job had the customer refused to repair these because the wall would not have been able to support the weight of the cement boards and tiles.

If it turns out that one of the walls is load bearing then here in the UK a building warrant is required by most local authorities for the repair work. That work often has to be carried out by an accredited joiner recognised by your particular local authority though this may not necessarily be the case. The standard of the work will certainly be inspected by building control prior to any further work commencing upon your bathroom. I would certainly recommend that you do not use the bathroom installation company you’re thinking of for this type of work, they most often will not have the particular expertise for this type of work, which requires temporary bracing of the remaining ceiling and structure whilst work is ongoing. Again this all costs more.

Any repairs works mentioned so far then become even more complicated and expensive to rectify if there are existing plumbing and electrics in the stud wall area. Photo 2 below is the same wall as shown in the base of photo 1.

As you can see the plumbing pipes had to be removed. There was a cold supply coming from the attic cold water tank and a hot water supply pipe below floor routed up into the stud wall to supply the old bath. There was an additional cold water pipe for the electric shower. This had to be removed completely and re-instated once the wall was repaired instead of simply amending it for the new shower. There were multiple lighting circuit cables for both the upstairs and downstairs lighting circuits routed up through the stud wall. At the base of the adjacent stud wall was a socket for the ring main. These all had to be disconnected the cables removed, and then re-instated. This work is simply not a five minute job and didn’t just cost the customer an extra £5.

This is why building a bathroom properly to avoid the problem of rot is so important. We wrote an article on waterproofing a bathroom which also covers the correct method for building a shower. I’d suggest you give it a read.

Relocating plumbing pipes or electric cables

The photo above was taken during the conversion of a bathroom into a shower room. When we pulled the bath out the 22mm cold and hot water pipes which fed the downstairs bathroom and the lighting and ring mains circuits were found routed above the joists below the bath. The old bath panel was not going to come out without basically destroying it so at the survey and quotation stage checking this wasn’t possible. With the conversion to a shower room these had to be relocated below floor level. Luckily where these pipes and cables disappeared outside the perimeter of the room downstairs there was space below the timber to allow them to be cut and dropped below. To do this the next joist along had to be notched to allow the pipes to be dropped below floor level. The plastic pipe was then disconnected from the copper fittings not seen in the photo and pushed back into the wall and then pulled back below the timber. New copper pipe was soldered connected to the existing copper pipework and then connected to the plastic in a way that did not result in a bend on the pipe as shown in the photo above. Although plastic pipe is flexible straining it like it was in the photo is never a good idea.

The electric cables were cut and dropped below the joists then reconnected using what are referred to as maintenance free wago 221 connectors inside a wago 221 junction box closed by cable tie. An access hatch was left in the plywood subfloor once laid that means should there ever be a need to access then it is possible. I would have preferred to replace the cables which would have been ideal but couldn’t. When the associated downstairs sockets were identified and an attempt made to pull the cables they didn’t budge. The original builder had obviously not followed good practise and run the cable in conduit in sections where it was a tight fit. These cables may have come out but running new ones would have been impossible without demolishing most of the walls and downstairs ceilings on the front of the house.

Water shut off valve

Some customers have no idea where the mains shut off valve to their property is located. Some don’t work and allow water to continue passing. The water in the street then needs shut off to replace the property stop tap. This has to be done for mains pressure properties that do not have storage tanks in the attic commonly referred to as gravity systems because if we can’t fully switch the water off then other means have to be used to do so to allow us to solder copper fittings. All good plumbers will be aware that it is very hard to solder pipes even with a bit of water in them.

If you do have tanks in the attic do the shut off valves both supplying and then feeding various outlets work? 50% of the time they don’t having never been serviced so work needs to be done on them first. 

Central Heating Drain Valve

Inevitably as part of a bathroom renovation removing and installing a new radiator or towel warmer is necessary. If the pipe work needs altering which is nearly always the case then the entire system needs drained down. Quite a number of properties don’t have central heating drain valves. This is something we do check for at the quote stage because of the headaches it can cause. In a house with a garden and drain it is relatively straightforward to shut off both valves to the lowest radiator and drain that down collecting the water in various containers. Then a hose can be run outside and the valves opened to drain the rest of the system. In a city flat however this isn’t an option. Instead again drain a single radiator and then fit a drain valve not only for our own use but future use. Then using multiple containers drain the system and decant the water down the sink or toilet. You can’t run a hose to the these if they are above the height of the radiator system since water doesn’t drain uphill. We have on one occasion tapped into a sink waste pipe to allow a hose to be run to drain down a large system and then repaired the waste pipe. This was quicker than taking hours to manually drain the system. Once drained install a drain valve onto the lowest radiator, this makes our work easier and is a future convenience for the customer getting any other work completed. 

Moving Radiator or Towel Warmer

Not too much of a problem if it is to be moved only slightly from the present position to the new. To move it elsewhere can be problematic. Wall mounted towel warmers located at the entrance to a shower or over a bath can require a lot of additional work re-routing pipes up into the wall even if plastic is used, and doing the joinery work to make sure that when mounted the unit is secure. More time is required if the pipe work is done in copper. On one occasion when working in a listed building the customer wanted the new towel warmer on the opposite side of the room. Taking the pipe work through new holes drilled into the Oak joists was not an option. So the pipe work was run up into the stud wall, along the room and back down into the floor space. Again not a quick job.

Moving a toilet or soil pipe work

In most projects moving a toilet is very restricted due to the run of the soil pipe from the toilet carrying the waste. The soil pipe can be moved parallel to the joists either extending or shortening in either direction. What cannot be done is cutting through the joists completely to run the soil pipe elsewhere. Moving a toilet isn’t that big a job when all that is required is either the shortening of the existing pipe or extending it with the use of a coupling. Horizontal soil pipe couplings should always be solvent weld, not push fit which will eventually leak. However as occasionally happens removal of the old floor reveals the poor standard of workmanship previously carried out. The photo below shows more extensive alteration to the soil pipe.

This job the customer wanted the toilet moved. The previous soil pipe installation had actually been done using underground drainage pipe and push fit fittings. You can see in the photo the new white waste pipe from the shower. The old one ran straight through the hole in the joist straight ahead into the old orange pipe. Had it been left in that position it would have been too close to the toilet waste connection. Thus instead of a relatively simple alteration the whole lot had to come out and a new pipe with connections installed. If you look at the coupling on the left you will notice pencil marks on both the pipe and the coupling. These as any decent plumber will know are used to mark the position, angle, orientation etc of the assembly prior to gluing it together to ensure that when it is actually glued the layout and the drainage works as required. This all takes time making sure that the satisfactory removal of all waste water is going to be achieved once the assembly is complete. You will notice on the right hand side of the photo the sink white waste pipe and black fittings feeding into the soil pipe via an adapter. This adapter was orientated in the housing of the soil pipe at the highest point of the soil pipe to make sure that in tandem with the good gradient on the sink waste pipe waste products would not clog up the sink waste pipe. You can also see the additional timber added between the joists to make sure that the weight of the toilet and a person would be supported and not just by the new plywood laid to replace the rotten chipboard.

Tiling Requirements

In the photo above what you are looking at is the joinery work for the installation of two tiles shelves commonly called niches or cubby holes in the industry. You will see the two blue clamps holding the wood together. At the bottom of these clamps where the timber is only present on three sides not four like above is the void spaces were the lighting was installed. Getting all this joinery work done so that once the tile cement boards were installed resulted in them all being, flat, square, plumb and level took time. If they weren’t then the tiling would have been poor. The final result of that is the cover photo to our homepage. The tiling itself also took considerably longer having to make all the cuts, and get the trims installed. Compared to the time it takes to do a standard wall with preparation work and then the tiling this type of work does take considerably longer and as a result the price goes up.

Grouting – Simply put smaller tiles result in a lot more grouting. With big tiles one tiler can grout from start to finish in half a day. With small tiles over a large area one or more days with clean up time involved particularly with metro tiles that have a bevel on them around the sides, they make grouting a slow process. As a note installation time of big tiles vs large tiles for an experienced tiler is not that different. Large tiles require back buttering i.e. putting adhesive on the back of the tiles too to ensure suitable adhesion, clipping levelling clips as well. Small tiles don’t. So for an average bathroom shower area installation there is not really a great difference for the tile installation time.

Floor tiling – If you look at the information regarding preparation of a floor for tiling on our tiling page you’ll find that it does take a while to ensure suitable installation. Making cuts etc for plumbing supply and waste pipes again more time, especially if the tile is hard porcelain. Planning the tile layout as well to avoid poor cuts or tiny slither cuts across obvious areas like doorways where the eye is drawn to is necessary again taking more time. Luxury vinyl is much quicker and cheaper on the materials.

Plastering & Painting

Any plastering work that needs doing needs time to dry out before painting. I would always suggest at a minimum that 1 week of drying is required. This depends upon the type of paint used. You may have heard of bathroom paints I.e acrylic paint and vinyl paint. What gives these their vinyl and acrylic properties is micro plastic contained in the paint, more in acrylic than vinyl. The drawback to these paints is that the micro plastic effectively seals the wall preventing the escape of any moisture present i.e. from plaster that isn’t yet dry. Try and rush the painting and the trapped moisture will cause the paint to blister and peel. Plastering will cause delays in the completion of a bathroom.

Job Location

A factor that for one reason clients seem not to take into account regarding costs. A home with a driveway that a skip can go on is a much better option than a city flat that requires a council permit for the skip and the additional work of hauling the waste to the skip rather than one set of stairs as with a typical house. Council skip permits can be just as expensive as the skip hire itself. City parking costs add up increasing the price of the job. Delivering materials and fittings to a city flat can be very difficult depending upon the location of the flat. Main street city properties will often require very early morning delivery in compliance with loading times displayed around the locality. Hauling all this up the flights of stairs in blocks of flats will require additional help. One job the total weight of the materials was over 2 tonnes (2000)kg to the fourth floor flat. The cost of this was added to the job compared to a home with a driveway job.