Welcome, Guest. Please Login or Register
Welcome To Ask The Trades!
Oct 24th, 2021, 3:34am
Quote: Earth first! We can strip-mine the other planets later.


Page Index Toggle Pages: 1
Send Topic Print
Cracks in floor (Read 155 times)
TrevorP
Junior Member
**
Offline

Ask The Trades
Posts: 89


Total Thanks: 0
For This Post: 0



Cracks in floor
Sep 28th, 2021, 12:37pm
 
More problems, after removing carpet files we found we had ceramic tiles underneath and these had around 6 cracks from wall to wall in. There are no cracks in the walls. I have removed a few tiles and broke out the under floor were a crack was, found that it is about 50 mm thick sand and cement screed on top of a concrete base. The cracks do not appear to go into the concrete. In my onion the s&c screed is very weak and I think it was only the tile adhesive holding it together.  
I think that I will have to remove the screed completely and re-lay new floor , unless anyone has a better solution? I thought a 3:1 mix would be stronger. The house was built in early 70s and not even sure if there is a dp membrane under.
Is this the way to go, is my mix ok any help please.
 Thanks

Image 1   

Image 2   

Image 3   

Trevor
Back to top
« Last Edit: Sep 28th, 2021, 9:18pm by Lectrician »  
Thank User For This Post View members image gallery  
IP Logged
 
woodsmith
Global Moderator
Trade Member
Author
*****
Offline


Posts: 4357


Total Thanks: 128
For This Post: 0


Gender: male

Trade: Joiner

Re: Cracks in floor
Reply #1 - Sep 29th, 2021, 9:18am
 
What flooring are you planning to use in this room?
Back to top
 


Thank User For This Post View members image gallery  
IP Logged
 
TrevorP
Junior Member
**
Offline

Ask The Trades
Posts: 89


Total Thanks: 0
For This Post: 0



Re: Cracks in floor
Reply #2 - Sep 29th, 2021, 9:36am
 
Because it is is a type of conservatory/garden room we thought either re-tile or a Karndean type, needs to be mopped regularly with wet dog.
Would it be possible to put some type of insulation down?, my restrictions are height as can only get total including the finish a max of 60mm due to door opening, just a thought!
Trevor
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
woodsmith
Global Moderator
Trade Member
Author
*****
Offline


Posts: 4357


Total Thanks: 128
For This Post: 0


Gender: male

Trade: Joiner

Re: Cracks in floor
Reply #3 - Sep 29th, 2021, 11:44am
 
Right, you have a few options.

Firstly I don’t think the cracks sound like anything to worry about. No decent tiler would lay tiles directly onto concrete these days as they are so prone to cracking.

I’m just coming up with a few ideas as only you can judge the conditions as you move on with the job.

So, if you want to lay tiles I would recommend using one of the tile backer systems, normally a plastic mesh, but there are other systems. Because of the height issues you will probably have to remove the tiles, then you could possibly use a self levelling compound rather than dig out all the screed before putting the backer down.

If you want to add insulation then you would need to dig out all the screed. If it’s soft it will come up easily with an SDS breaker. If it’s really hard I would go back to previous plan and tile. Once you have the screed out, unless the floor is flat and smooth, level the floor with self levelling screed. Once completely dry use 25mm roofing laths all round the perimeter and lay a few across the room. Fill  between with 25mm foil sided insulation boards then lay a damp proof membrane over the whole floor and ideally up behind the skirting. You can then put t&g chipboard, loose layed, on top glueing all the joints and leaving 10mm round the edge. There are different thicknesses of chipboard so you can pick one to give you your required height. This gives you a perfectly flat floor on which to lay a vinyl plank type flooring.

So, if you count a few mm for levelling screed, 25 for insulation, 22 for t&g and 6mm for flooring you are just below your 60mm max.

Hope that helps. I’ve fitted insulation like this on my own home and it makes quite a difference to the comfort levels in the room.
Back to top
 


Thank User For This Post View members image gallery  
IP Logged
 
TrevorP
Junior Member
**
Offline

Ask The Trades
Posts: 89


Total Thanks: 0
For This Post: 0



Re: Cracks in floor
Reply #4 - Sep 30th, 2021, 8:58am
 
Many thanks for a very comprehensive reply, you have given me some good ideas to think about.
I have started removing the tiles and boy they are really stuck down, but what I don’t understand is why the screed cracked so badly, was perhaps because 45mm to thin a screed, and it comes away perfectly from the concrete base, should it have been sealed before laying, or should some kind of reinforcement been added?
At least getting my moneys worth from my sds, thanks for your good advice.
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
woodsmith
Global Moderator
Trade Member
Author
*****
Offline


Posts: 4357


Total Thanks: 128
For This Post: 0


Gender: male

Trade: Joiner

Re: Cracks in floor
Reply #5 - Sep 30th, 2021, 1:44pm
 
45-50mm is normal thickness for a screed and screeds often crack especially if they dried too quickly. Under most flooring it doesn’t matter but that’s not the case with tiles which is why they have developed various methods of decoupling the tiles from the screed. If it’s coming up really cleanly then that’s a bonus if you want to go down the insulated floor route.
Back to top
 


Thank User For This Post View members image gallery  
IP Logged
 
TrevorP
Junior Member
**
Offline

Ask The Trades
Posts: 89


Total Thanks: 0
For This Post: 0



Re: Cracks in floor
Reply #6 - Sep 30th, 2021, 7:08pm
 
Ok, tiles removed and as screed coming up quite easily we have decided to take your advice and put down insulation as per your comprehensive suggestion. Very difficult to get builders around here at moment, so this looks like a nice diy job over winter.
Thanks for your assistance
Trevor
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
woodsmith
Global Moderator
Trade Member
Author
*****
Offline


Posts: 4357


Total Thanks: 128
For This Post: 0


Gender: male

Trade: Joiner

Re: Cracks in floor
Reply #7 - Sep 30th, 2021, 10:09pm
 
Best of luck, much better to do it yourself then you know it’s done properly.
Back to top
 


Thank User For This Post View members image gallery  
IP Logged
 
Page Index Toggle Pages: 1
Send Topic Print