In this post I will describe how I built a cheap and easy shower for my tiny house using corrugated galvanised steel sheets.
The shower cost around 200 Euros which included the base, sheet sides, waste plumbing, fixings, sealant, shower curtain and shower head.
I can’t claim any originality regarding this use of corrugated galvanised steel. If you look on Pinterest you can find plenty of examples.
But what is the point? Why use agricultural roofing sheets for the walls of a shower?
Firstly, I like the way it looks. The rustic/industrial aspect fits in well with the sanded pine boards on the walls. I also like the idea of using materials in an unusual way.
Secondly, it avoids the need for tiling. I have done quite a lot of wall and floor tiling over the years and I was keen to avoid it in the tiny house! It’s not that I hate the process of tiling but I wanted something different. Furthermore, the lime and hemp walls were never intended to be completely flat and would not be the ideal surface to tile on. These undulations could be easily accommodated by using the sheet material.
Thirdly, I expected that the shower could be built quite quickly in this way.
Lastly, this system fits in with the low budget ethos of the tiny house. The sheets only cost 11 Euros each (I used 3 of them). Admittedly, the box of fixings cost another 30 Euros, but even so, that’s still very little.
My thoughts regarding the design of the shower are listed below.
I considered various options for the shower base such as a large plastic bucket, a wooden barrel, cast concrete, a plastic shower tray from a caravan and even tadelakt (a traditional type of Moroccan polished plaster).
One by one, each of the above options were rejected. The bucket looked awful and the wooden barrel was too small (as was the caravan shower tray). The cast concrete and tadelakt options would have been a lot of work with a high chance of them going wrong.
In the end I chose a ‘normal’ ceramic shower base which measured 70cm x 70cm. This was just big enough to be comfortable in use but small enough to fit into the tiny shower room. It was also cheap (about 50 Euros) and I knew that it would work.
Needless to say, I didn’t want the shower enclosure to leak.
The ceramic shower base had a good sized upturn at the edges so I thought that, in combination with a shower curtain, it would work ok.
As for the steel sheets themselves, I didn’t want to make any more holes in them than necessary. For this reason and for the sake of simplicity I decided not to use a normal thermostatic mixer valve and handset. This would have meant cutting large holes halfway down the shower and the curved nature of the panels would have made the installation difficult.
Another potential source of leaks could be where the steel panels joined together. I decided this could be minimised with a large overlap and the use of some clear silicone sealant.
I also thought that a bead of silicone should be enough to seal the join between the steel sheets and the shower base. A timber capping strip at the top would prevent any splashed water from running down behind the sheets.
Finally, I knew that if the shower room walls did become a little wet, it wasn’t the end of the world. The lime and hemp would soak it up and then release it back into the atmosphere later.
As I would be using a conventional shower tray, the waste plumbing would be standard and should be straightforward.
As for the hot water plumbing, I had already rejected the idea of a normal thermostatic mixer and handset so I needed to find another solution.
My preferred idea was to locate the thermostatic mixer valve outside the shower room so that the hot water to the shower already arrived at the perfect temperature. In this way, I would only need one pipe going to the shower. Flow could be controlled by a simple manual valve, just outside the shower. The hot water pipe could be run around the edge of the shower sides and terminate in a shower head at the top. This seemed to be a good compromise between simplicity and convenience. You can read a bit more about the hot water system here.
Obviously, there are numerous even simpler options such as the Hozelock porta shower, a portable electric shower (supplied from a bucket of warm water) or even just a basin and washcloth.
Installing the base
The drawing below should help illustrate my method of installing the shower base.
The first thing I did was make a rough timber support frame for the shower tray. This should be quite chunky and tall enough to allow for the shower waste plumbing. Note that I left a gap at the front. This was allow me to check for potential leaks from the waste water pipe and fittings. It might also be handy in the event of future leaks, although access is very tight.
I screwed the frame down onto the timber floor. Given that neither the floor, nor the ceramic shower tray are likely to be completely flat, it is possible that the tray will ‘rock’ slightly on the support frame. The upper surface of the tray may also not be level. You could try to adjust the frame by inserting wedges or packers underneath, before screwing it down. I was lucky this time and found that tray actually sat quite nicely. I bedded the tray down on a decent bead of silicone and ran another bead of silicone around the tray where it met the wall. When the silicone set, the tray was ‘wobble free’.
Next I poured some water down the shower drain hole and looked through the ‘access gap’ to make sure there were no leaks. Again, my luck seemed to be in as the floor under the shower stayed dry. To be honest, my plumbing skills are limited and I found that connecting the waste plumbing and fitting the base to be quite a fiddle.
The final part of installing the base was to screw on some trim panels to the front and side. These were nothing fancy – just some timber offcuts cut to size. The thickness of these trim panels will determine the outside dimensions of the support frame. Ideally the panels will be flush with, or just stepped slightly back from, the shower tray.
Fitting the shower curtain
I was keen to get the shower curtain height just right. Ideally it would extend far enough into the shower tray to minimise the amount of water getting splashed onto the timber floor.
The choice of available curtain rails was poor (they are obviously not a very fashionable item these days) and I ended up with a cheap and cheerless item from a large DIY shop. Although the aluminium and plastic used in its construction was very flimsy, I made sure to install it as carefully as possible and it has actually been ok in use. As the ends of the rail need to be fixed to a flat surface I chose to install it before fitting the corrugated steel sheets.
Adding the steel sheets
The first task was to screw three rows of wooden battens to the wall to provide a fixing for the steel sheets (see below).
Next, two of the steel sheets were trimmed from 90cm down to 70cm and were stood in place on top of the shower tray. The cut edges were placed at the inside corner. The sheets were also cut to fit around the shower curtain rail.
The third steel sheet was bent in the middle along its length and fitted over the first two sheets, overlapping by around 40cm each side.
The steel sheets were then drilled and screwed to the battens using the special fixings shown below.
Although its not very clear from the above image, there was in fact a rubber seal between the large shaped washer and the screw head, so I’m quite confident that little (if any) water could penetrate the hole and get behind the steel panel.
The fixings were quite easy to use. After drilling a pilot hole, a small socket on the end of my cordless drill was used to drive the screw home. Some care had to be taken not to screw too far, as the sheets could be deformed. This was more likely to happen where the sheets had not been ‘doubled up’.
If you couldn’t get the special fixings (or wanted to save some money), I suppose you could get away with normal screws with a rubber washer and/or a blob of silicone behind the screw head. It wouldn’t be quite as neat though.
The final job was to add a timber capping strip along the top of the shower and seal all the joints with clear silicone.
Fitting the corrugated sheets, from start to finish, took one afternoon and was not particularly difficult.
An unexpected and slightly negative effect of using the steel sheets is that I could actually feel their ‘coldness’ when standing in the shower.
In practice, with a good flow of hot water from the shower, this slight discomfort soon disappears!
Other than that, I think the galvanised steel shower looks good and works well. As a bonus, it is easy to clean and I don’t have to worry about mouldy grout lines.
I know that the galvanised steel will rust eventually. However, according to this website, the zinc layer could last 10 years, even in wet or soaked environments. If that is the case, I’d consider that my 33 Euros have been well spent!
Update: Sept 2023
Two years on from building the shower and I can report that all is good.
The sheets have not started to rust, it doesn’t seem to be leaking anywhere and nothing has fallen off or broken.
Admittedly the shower is only used for (at most) 2 months of the year. Nevertheless, I think this type of shower was one of my better ideas 😉