Buoyed by a positive response to me recent experience of laying a new wooden floor I thought I would share an experience from last year on laying a kitchen floor.
First I have to say that this was the most depressing job I have ever done, partly because of the time pressure of having to finish within a few days, but also because I had no kitchen, and the work was physically draining.
The floor I had was concrete, nice and flat but covered in a horrible bitumen substance. Fortunately having read this group I knew that I couldn't just put the floor tile adhesive onto the bitumen as it wouldn't take. Incidently the salesperson at the local specialist tile supplier in Ewell told me not to worry about it and it would probably be alright! Nice one!
Unfortunatley I worked out that I needed to remove the bitumen the day before I was doing to do the work. The only way to get it off that people thought would work was a breaker with a comb attachment. The idea being to touch the breaker on the surface and break it up a little to expose the concrete underneath.
So I hired one for a day. It weighed a tonne and the rental shop tried to pass me off with a flat breaking bit saying that would work. If anyone tried to tell you this will work dont believe them. It does break the surface up - into big chunks. The slightest touch was enough to release a chunk of concrete.
Having insisted on the right attachment I set to work. The process of touching the breaker lightly on the surface really tests your arm muscles, I was shattered after 30 minutes. Unfortunately it took 6 hours jsut to get about 50% of the surface exposed in a 10m2 room.
With hindsight I should have hired a smaller breaker which would have been gentler and been easier to handle. Incidently also make sure you get lots of the comb attachments as they get worn down competely each half an hour. Also with hindsight I would have isolated the kitchen more from the rest of the house and used a better dust mask. The amount of dust doing this job was huge.
The next problem was that I thought I should start with a flat surface before starting the tiling. I had heard about self levelling compound and thought I would use this. With hindsight this was not really necessary. It was expensive, a nightmare to mix (the hired manual mixer ground to a halt once more than half the mixture was introduced - I had to put my hands in the mix to break up the lumps by hand!). Having poured it all into the floor and thinking I had it flat I dicovered after it was dry that there was a hump in the middle. Looking back the best thing to do would have been to use a cement and sand mix to fill in most of the holes as best I could and tried to use the original bits of the floor to make it approximately level. This would have been far cheaper and a lot less hassle.
As it was I then had to use lots of extra floor tile adhesive to try to make up for the not so level floor. This pushed up the cost again. Fortunately I had the sense to hire a cement mixer which made the job a lot easier. Incidently if I had to do self-levelling compund again I would also hire a cement mixer, The break of being able to make a cup of tea while the mixer does it's work is invaluable - and they're quite cheap to hire.
Using all this extra floor tile adhesive meant that I had a harder job ensuring that the tiles were level. I made the mistake of starting at the highest point (which happened to be in the middle of the new french window) and using too much adhesive. A bit more time spent establishing the highest point and using the minimum adhesive there would probably have reduced the amount of adhesive used by about 30%-40%. I thought afterwards I should have poured on some water to find the level. It seemed a messy idea at the time but it would have been smarter looking back.
Another thing to watch out for is the level gradually creeping up. If I did it again I would spend a lot more time on getting the outside tiles exactly level. Extra time doing this would have saved time later. It also increased the amount of adhesive I needed even more
When it came to laying the tiles I found a couple of useful tips. I found it a good idea to remove the spacers before the adhesive had fully set. Otherwise getting them out was a real pain. It's usually possible when its OK to walk lightly on the tiles before fully cured. Secondly I would recommend getting a diamond blade tile cutter. I got one from Screwfix for about £50 and it made light work of difficult corners and straight cuts. I tried a hired manual cutter and there was no comparison. Care needs to be taken at the end of the cut though as the corner could break off - even if you got really slowly. I found it best to stop a little short and cut in from the other end although this needed some care to get it aligned. It was best to score the line to cut along and then use a permanent pen to mark the ceramic. This way you could still see the line through the rush of water over the blade.
On the laying of the tiles I would warn people to look carefully at the pattern on the tiles if it is feint. My tiles had a slight horizontal pattern which I didn't pay enough attention to when laying some of the first tiles. Fortunately you have to look closely to see that some are at right angles to the way they should be, however I know they are there - which is annoying.
So gradually I managed to cover the entire room and it started to look good, apart from the gentle rise into the corner which I tried to compensate for by adjusting each tile slightly as I back filled. I discovered that as long as I back filled and ensured the three corners were pretty aligned as I filled I any slope was not rally that noticeable.
Fortunately The highest point is now under the cabinets and the kitchen fitter was able to work with the height difference so I got out of jail. In fact as slope goes away from the wet area water tends to run out from under cabinets which is quite useful.
Still I would recommend spending more time than I did paying attention to the slope in the first place as it was very fiddly checking each tile at a time as I had to in the end.
Anyway hope this help anyone considering laying floor tiles on a concrete base, especially it there is bitumen on the existing concrete surface.
Elliot