Can I restore this floor using Durabase CI matt ???

[Tenazes]

Hello people,

I'm restoring an old house and I am about to cover the floors with ceramic tiles. The problem is that the floor consists only in a mortar layer laid over some gravel directly on the soil. The mortar layer has some cracks and recently I've found (while opening paths for electrical wires) that in some places it consists in 2 layers that became uncoupled.
Searching this forum I've found Durabase CI ++ uncoupling matt... it is almost a miraculous solution...

Will it work in my case?

I'll attach some pictures .

 

[DHTiling]

Honestly... wouldn't touch it with a barge pole.. wrong in so many ways.

 

[bugs183]

As above!
For the cost of bodging it you may as well dig it all up and lay a proper floor laid with a damp course.

 

[Gazzer]

Not for me, too much of a risk. I very much doubt Dural or Ditra would approve either !

 

[Del W]

No.Wouldnt do it.

 

[Tenazes]

Thank you all for your honest comments. This is really a great forum!!
First of all, please excuse my english because it is not my maternal language

I'm an ordinary guy that want to go out of the city and I bought this very old house. I'm doing all the recovering by myself, trying to do the best possible job with the available knowledge, budget (small) and time.
Although the pictures look bad, the cracks are very old cracks possibly due to rain water infiltration over the years and first years natural movements. (the roof was in a bad shape and all the roof had to be changed - for that job I had to hire someone) .
The rooms are a kitchen and a bathroom with approx. 15 sq.mtr and 5.5 sq mtr
I was suspicious about laying the tiles directly over this floor and that was when I found out about Ditra and Dural. These seemed to be a miraculous solution that would prevent me from digging everything up. As these matts can even be layed over wood floors that have a considerable natural movement I thought these would be a good solutions for my case.

I see that it is general opinion that this is not a good solution...

- Can you suggest anything else outside from digging everything (I am already placing the electrical wiring and starting the wall tiles and this would be a major setback) ? The sewers are also already layed.
- What can happen? Cracks appearing on the tiles anyway? I understand that for a professional starting a job this would be a high risk, but for someone in my position, would the risk be preferable to digging everything up?

Sorry to keep bothering you, but I really need some help on this

 

[ythan]

I note that you're in Portugal , so I'm thinking rising damp in the floor is not going to be a problem as it would be in the UK.

I think you may get away without digging all the floor out.

How solid is the floor solid -is there any movement, new cracking, when you jump on it - also no vertical movement, either side of the existing cracks?

 

[bugs183]

Sorry mate, you'd be crazy laying tiles on this, there is no strength there.
I bet it's super absorbant as it looks so dry, you could try a water based epoxy primer/bonder, diluted. This would penetrate into the floor and set. This might work, but how well and for how long is anyones guess.

 

[Rizzle from the Portizzle]

take the lot up should need no more than a feather and tooth pic now lay exspanding metal screed in sand and cement the whole deph add ronafix to the mix keep wet for a week by spraying with water after it hardens now you have 100 year floor make sure the sub base is well compacted

 

[Tenazes]

Many thanks!!


In fact rising damp is not a problem as it would be in the UK. With the roof fixed and the rain water correctly drained I don't think I'll have problems with that. I am working on that house for over 1.5 years (a long adventure...) and even with the old roof there was not so much damp. Anyway, I was thinking that Durabase or Ditra matts provide good impermeability, leaving the borders with no sealing to allow any vapour to escape.

I'll have to make the jump test to be sure, but I've never noted any movements or new cracks. In some areas, when you bang on it with something it produces a hollow sound (probably detached areaS). For a time I've stored there about 20 bags of pre-mixed mortar (25 kg each) on a pallet and when the roof was being changed the floor supported a large pile of rubble. I didn't noted anything.
One set of cracks was always there, but there is another one that I'm not sure.
Although it seems very fragile on the above pics, It was not so easy to break when I was digging the electrical wire paths. Sometimes large pieces came out without breaking. There was even an "island" remaining and I could walk on it with no problem.

Will the jump test be enough to know that Durabase will work?

Breaking solutions are no doubt the most safe bets, but would also be a major set-back.

2 more pics for the whole floor...don't mind about the mess

 

[ythan]

Looks like your existing floor is pretty stable in the photos, and both areas are fairly small. Actually, I wouldn't use durabase or any other uncoupling layer - I think it'd be an unnecessary complication on your floor.....simplicity is always best where possible.



I think the most important thing will be the correct mixing and spreading of the adhesive with good notched trowel. I'd use BAL single part flexible and BAL wide joint flexible grout (or similar products). Important that the adhesive is worked well onto the existing dry screed, and is of sufficient depth to ensure a full flat bed is achieved under each tile. Use large tiles say 300*300 min. Take your time bedding down each tile, jiggling and thumping the tile with the side of your fist. Maye a good idea to lift the first couple of tiles to check a full flat bed is being achieved. Maybe also a good idea to just do the smallest one of the floors and see how that goes. If the tiles all seem good & solid after say 2/3 weeks - then do the other floor.




If the existing floor screed is not flat enough, you may need to put down a self levelling screed before tiling, but I'd avoid it if possible.




Another alternative would be to lay 22mm marine ply boards onto say 75 wide*30mm thick timber battens @ say 350 centers, leveled &solid bedded onto the existing screed. Then tile on top of that. I'd also lay a Visqeen 2000 polythene sheet (or similar) over the screed first, as it's so cheap, if there's any doubt about rising damp.

 

[Tenazes]

Thank you for all your help.


Simplicity is usually the best option!! Unfortunately sometimes when you don't have much knowledge on what you are doing and you are trying hard for things to be done correctly you tend to complicate and pay attention to many non important details. This is my case, I've started this adventure and many headaches later I've manage to install the piping and sewer, use lime on mortar mixture on ancient walls, etc...When I'm finished (on year 2050) I'll be able to build a house anywere... :lol:

I had already ordered Durabase matt, so it is too late ... but if I had your encouragement sooner I wouldn't have done it...
Anyway, this will only reduce the possibilities of things going wrong...

I cannot find BAL in Portugal (unfortunately because their range seems to be a very good one), but I'll use C2 class.

I'll post some photos of the works as soon as the matt arrives.

Thanks again... I'll sure have some more doubts soon

 

[ythan]

Sounds like you're doing a grand job.

Best check on the Dura web site what adhesive they recommend etc for bedding the Dura mat down and for tiling on top of it. Not sure if Dura recommend C2 class for their mat.

Also best to finish one floor completely before doing the other, ie take the opportunity to learn as you go.

 

[Tenazes]

Thanks again.
I'll read all the Dura instructions carefully before I start. I'll also follow your advice and start by finishing one floor completely (the smaller one).

I'll post some pictures of the finished floor as soon as I get to it (and the mat arrives)