Patio Problems

[SyAccursed]

The patio is about 4-5 years old and was installed by my late Dad, who seems to of done a dodgy job. The patio has always had a dip in it where water collects to one side but lately all around the perimeter substantial cracks have appeared in the brick work and edge tiles have come loose. There is no form of drainage on the patio construct (eg drainage holes or a drain or gutter) and it definitely seems generally moist as all most of joins between the tiles sprout moss and weeds.

Lifting one tile today we found the cement layer beneath to be damp, of a an odd blueish hue and contains many air bubble holes; this layer appears to have no adhesion to the bricks and foundations below and crumbles under minimal pressure. Below this the foundation concrete itself appears to be fairly damp and some area in the brick work are the same texture and consistency as unset cement; this foundation while moist does appear to be solid and has dried out reasonably quickly when exposed.

Edit: Its now had time to dry more thoroughly and based on the remaining water pattern I am 90% convinced it is the layer of cement between the tiles and the foundations that is retaining water. and that the foundations themselves are largely dry.

Slightly concerned about the stability and safety of the patio and what, if anything, can be done to solve these issues.

Pictures for illustration, first the crumbling layer from directly below the tiles second the foundations and brick work which is damp and third a example of the worst cracking in the bricks.

 

[r896neo]

Ok here a few ideas for some of the issues. First off don't worry it's not unsafe, at worst the edge flags would lift and could cantelever off the edge but they don't look like they overhang by a lot.

The concrete foundation will not be adversly affected by wet or dry but mortar will depending on how it was made.

The cracks in the brickwork is settlement meaning the foundation was on bad ground or the concrete was not deep enough and has cracked. It's not going to go much further probably but if you can live with the cracked bricks then just repoint or replace bad ones.

The dip should be removed, the flags will need to be lifted and re-layed with a fall to the nearest edge.

Some weep holes would be good but in reality if it's a raised area not a lot of water should get into it.

It's clear from you pictures and description the mortar the flags were layed with was perhaps the wrong ratios and or had far too much plasticiser in it but thats just a guess. It also appears to not have bonded well with the concrete base. Whatever the reason It needs replaced and in particular under the edge flags as these restrain the others.

The best job would probably be to lift all the flags and clean the mortar off and re-lay. If thats too much and you want to patch and repair then at the very least lift all the edge flags and relay and then repoint the whole area.