Barnboy

I'd go Marmox, they do various thickness', are waterproof, pretty strong and have a good key for tiling on to.

Thanks all when my tiles arrive I will pass this info on.

Where you tile through an internal doorway how tight do you tile against the door lining ?

@nod Are these the type of rubber door joints?

I'm going to have my ground floor tiled soon and need to let the tilers know what expansion gaps I want then to leave. I've got 65m² over 3 rooms so was going to get then to fit some expansion joint strips in each of the doorways and a 6mm perimeter gap, does this sound correct? They're modular porcelain tiles onto an anhydrite heated screed. What about at my external wooden doors, do you leave the same gap as at the wall junctions and fill with a good bead of silicone?

I understand that the longer you leave it before sanding then the harder it is to sand and the laitance seals the top of the screed and stops it drying. These screeds dry from the top down so they can look dry but still be wet down below. I haven't put any boards down, it's just been left to air, whilst I was plasterboarding I had a stack of boards on bearers laid down, the bottom of the stack was damp and this was a good 2 months after the screed had been poured.

I had an anhydrite screed poured at the start of October. All the info I have found has lead me to give it great care. What I have been told is, after 24hrs start giving it good ventilation, after 7 days give it a sand with a proper floor sander/ grinder to remove the laitance, you'll see it on the surface. I hired a grinder as the floor contractor went over it with a sander but I think he was being chased by Usain Bolt as he hardly touched the surface. You can turn your ufh on after 14 days and use that to help dry it out. I left ours 5 months before turning the heating on and couldn't believe the amount of moisture still coming out of it. I followed the info for tehnal shocking the floor by running my ufh later on, starting at 25⁰c and increasing by 5⁰c per day until at operating temp, keeping it att his temp for 7 days before slowly decreasing it by 5⁰c per day. I've now got a hygrometer box on the floor and am testing the Relative Humidity of the screed, I need to be 75% or lower, I'm at 74% at the moment. If the screed tests ok in a few places then as we're using Mapei adhesive I'll be priming it with their Primer G diluted, once that's absorbed and dry I'll give it another coat of neat Primer G at 90⁰ to the 1st coat before laying the antifracture membrane. I can't get hold of any gypsum based tile adhesive locally, otherwise I'd use that to lay the antifrac membrane leaving the cement based adhesive isolated from the anhydrite by way of the membrane. I'll also be putting in expansion joints at each doorway. 3 days after turning my heating off I noticed 1 crack in the screed, so they do have movement in them.

My water source has a ph 6.53, so I'm a bit worried about putting this straight in being slightly acidic.

I've looked through a couple of different Mitsi and Samsung manuals to try and find water specs but I haven't found anything in any of them yet. Heetgeek say under 1500 microsiemens for conductivity and ph is best at 8.2. I'm waiting on a some ph drops to arrive but I know from an official water test of my supply 2 weeks ago that the ph was down in the High 6's, What's the best way of raising this ? , I've got some salts for swimming pools but do these work long term, or is there something better to use ?

I'll need to find the info for the ashp that I was thinking of using and see what they spec, I also need to test ph etc as I've only had time to do the tdm so far. Maybe I'll try mixing a bit of tap water back in with some of the filtered water and see how it changes the readings.

@JohnMo I filtered my 1st batch of water yesterday, I ended up buying an aquarium filter system as it was a good price and an easy option. It consists of a pump, sediment filter, carbon filtwr, reverse odmosis filter and di unit. It produced 10ltrs of water per hour with a fair amount of waste water, they say 1:4 ratio, I tested the ppm before at 240ppm and after it comes out at a big 0, I had to retest a couple of times to make sureas I didn't believe the tester but it came up with the same result each time. Now I need to build my temporary Willis setup and get a power source to get it running.

I'm using Macphersons eclipse at the moment at 40% water as per the label, I've just put some tape on a wall I mist coated earlier in the week to see if its bonded. I used Teknos upstairs at the 10% water ratio as was listed for it, that didn't work out of well !

Thanks @JohnMo that's one of the ones I was looking at so nice to know its good.

I'm going to be filling the system with a pump out of cans of water that I've sent through a reverse osmosis and DI filter so I won't jabe mains pressure to set the system pressure, what should I be setting the system pressure to and what pressure prv should I add to my willis setup ? Thanks

Has anyone used a hygrometer and be able to give a recommendation on which one is a good one please ? I have an anhydrite screed that I need to commission and check the relative humidity of. I've been quoted £220 per test, I could need more than 1 if the first test shows the screed is still to damp but looking online there are plenty advertised for less than £200 so I'm thinking I'd be better to buy one and sell on afterwards, I can then carry out multiple test on deifferent areas of the screed to be more confident that it is dry enough to tile. Thanks