Cracked red screed ??

[lewie]

I've been asked to tile what looks like a cracked red screed. It could be some sort of water proof membrane and is about an inch thick which has been laid over the original floor. The building is hundreds of years old. It's mostly solid although it's fair to say that some of it is 'floating' where it's cracked although it's not disintegrating.

My thoughts were to tank the cracks and then over lay with no more ply with flexible addy. Seal the joints and then tile.


The alternative would be to use a decoupling membrane and then tile.

Any thoughts/advice ?

Lewie

 

[TJ Smiler]

Soory mate i have no idea what a red screed is but im looking forward to seeing some of the replies good luck

 

[White Room]

Just because the building is old dos'nt mean the floor is, was thinking a coat of asphalt for tanking purposes but a picture would help.

 

[On one]

Red as in deep red/black pudding colour

 

[judge]

A polyutherene screed possibly ? Has it small flecks of white in it ?

 

[lewie]

Deffo red. I'm going back to the site tomorrow so I'll take a pic and post it.

 

[Jelthetiler]

Sounds like a concrete dye to me.

 

[Stef]

Sounds like a red painted screed to me.. [emoji1][emoji1]

 

[Ajax123]

When was it laid... Is it old 25 years plus or it is reasonably new... Last 6months?

 

[Ajax123]

Based on your description it could be a magnesite screed... Don't see them often these days. If it is it will be red right through (some were green) and they were used up to about 25years ago especially in old council properties. They don't stick to concrete hence they can delaminates and crack. You will find it almost impossible to stick anything cementitious to it and most primers will fail to work as well. Best thing to be done if it is magnesite is break it out and reinstate it with something else.

 

[White Room]

Based on your description it could be a magnesite screed... Don't see them often these days. If it is it will be red right through (some were green) and they were used up to about 25years ago especially in old council properties. They don't stick to concrete hence they can delaminates and crack. You will find it almost impossible to stick anything cementitious to it and most primers will fail to work as well. Best thing to be done if it is magnesite is break it out and reinstate it with something else.

In about 43 years in the game i have never seen these screeds laid...

 

[Stef]

Based on your description it could be a magnesite screed... Don't see them often these days. If it is it will be red right through (some were green) and they were used up to about 25years ago especially in old council properties. They don't stick to concrete hence they can delaminates and crack. You will find it almost impossible to stick anything cementitious to it and most primers will fail to work as well. Best thing to be done if it is magnesite is break it out and reinstate it with something else.

Alan I had one of these a few years ago in an old council property, it was a really dark green almost black & had a few cracks in it, I gave it a couple of whacks with a hammer & it all lifted out in sections.
Cleaned up the floor & levelled it out with renovation screed.
At the time I thought it was a tar like substance.

 

[Andy Allen]

Got loads of them round our way on the council estates. They look and smell like tar..

 

[Ajax123]

Alan I had one of these a few years ago in an old council property, it was a really dark green almost black & had a few cracks in it, I gave it a couple of whacks with a hammer & it all lifted out in sections.
Cleaned up the floor & levelled it out with renovation screed.
At the time I thought it was a tar like substance.

Yep that sounds like magnesite. They were generally either green or red. I beleive they were actually banned or at least fell from grace about 25 years ago.they were generally used in council properties but I have seen one or two in private builds.

 

[Perry]

You that old Mark? Have seen it before in a shop in Oxford Street dug it up. If I remember it was about 40mm thick.