Loose Patio Tiles

[Spud1975]

Hi , I am currently having a patio laid. The contractor has laid the slate but after drying over the weekend ,4 days, all the tiles are loose and can be lifted by hand. I sent the contractor a couple of pics and raised my concern. He advises the grout will hold it in place. He is currently away and has not seen the actual issue first hand yet. My basic DIY knowledge is that the grout is cosmetic and the cement should hold the tiles in place. Type 1 mot was laid and compacted, then slabs laid on  sand cement mix.  I feel the job has many of the correct elements but  something has been missed I would like a professional opinion before the contractor returns to site in a couple of days so I am in a position to understand my options and discuss with him.   If the job is substandard what are possible causes and what would be the best course of action to get the job back on track. Any comments advise would be greatly appreciated. 

[Jonny]

It probably needs a slurry primer to help the mortar grip. 

[Radian]

Oh dear. The days of mortar dabs are long gone. A continuous mortar bed is the only way to lay any kind of slab.

For more info have a look at this paving expert article

Also, as Jonny mentioned a slurry primer should have been applied to the slate as it's not the least bit porous. A mix of SBR and cement the consistency of runny porridge is brushed on just prior to laying.

 

Frome the article:

 Spot Bedding

British Standard 7533: Part 4 , which covers the installation of both concrete and natural stone flags or slabs, requires that these are laid on a "full bedding layer". This applies to ALL classes of pavements, including patios and driveways, not just the big projects undertaken in the town centre or on a retail park.

Edited May 9, 2022 by Radian

[Temp]

 

2 hours ago, Spud1975 said:

He advises the grout will hold it in place.

 

No.  I had some india stone on some steps come loose. Was hard to get it to stick down until someone here recommended an SBR mix on the back. That seemed to do the trick. Grout will break up if the slate can move because its not stuck down.

 

See also..

 

https://slateandstone.net/sbr-bonding-bridge-and-primers

 

Quote

Bond bridges/Slurry Mixes are also useful for DIYers and Professionals alike. Some materials, such as slate can be difficult to get them to bond to the bed, slurry mix is essential to prevent avoid rocking pavers.

 

But note the comment about needing to clean up as you go..

 

Quote

 

Disadvantages:

Work Clean! A Slurry mix is very stick and will set quickly, any spills will need to be cleaned up straight away.

 

 

Edited May 9, 2022 by Temp

[Onoff]

I just got flints to "stick" by using SBR. Good stuff. Just a cheapo 5L from SF/TS.

[Faz]

If the base is solid the grout will work ok - you can't have those hollow spots underneath though. It needs to be a wet laid cement bed - yours looks like near 100% sand.

 

If hollow spots are left (tap around each slab with a broom handle to find them) the slabs will eventually crack anyway.

[Makeitstop]

These are porcelain, not slate.

 

If all of them are like that one (which I'd guess they are) then your guy is either incompetent or lazy, or worse still, both.

 

Anyone with any experience would know these need priming with an sbr slurry.

 

Worse still is the absolute joke of a bed they've been laid on. As others have stated, they need a continuous wet bed that provides full coverage of area below slab.

 

Hope you get it sorted. It's simply not good enough as it is.

Edited May 9, 2022 by Makeitstop

[tillywiz]

looking at that work ,incompetent lazy and corrupt obviously thinks your a sucker and that he will get away with it ripping you off for the job.