Poorly built retaining garden wall...idea!

[Scousemooncat]

Hi All...

I am after some guidance or advice...I appear to have a shoddily constructed retaining garden wall in which water has built up over a number of years and caused the patio which runs from the house to start sinking towards the end...the back garden is on a slope downwards and has been split into 3 tiers the top one which is a patio then a drop to middle garden and then again to a bottom garden...

I lifted the patio paving stones and there wasn't much underneath - it seems that the mortar between hasn't been integral for some time and as such the sand support underneath has been washed away, hence the sinking...but owing to the fact that the retaining wall doesn't have any membrane or weep holes in, the water has had nowhere to go and caused the rendering to blow and a crack to appear in the wall...

It appears that the patio defect was first and then this allowed more water in...So my idea to fix it is to lift the paving stones back to where they are dry (checking and repairing the rest of the mortar)...then digging out the material behind the wall to allow me to get a membrane and some weep holes and drainage in there and drainage shingle etc stabilise the wall by re mortaring/pointing...then replace the backfill etc..and ensuring the patio is integral et ....does this sound like an idea? Its about 4m long and 5 ft high...built in about 1990 maybe?!

I can do the graft etc I just need to know this is the best way to go....

Any help would be really valued!

Cheers Simon

 

[tony1851]

Are you sure the patio-sinking is caused by water and not just poor backfilling behind the wall?
Also, if your retaining wall is rendered, you are fighting a loosing battle. Free-standing walls - and retaining walls particularly - should never be rendered. The drainage system you plan to install may relieve hydrostatic pressure on the wall, but it will remain permanently damp. The render will inhibit drying-out of the brickwork. The resulting dampness can cause frost damage in winter, and sulphate attack in some bricks. It is no surprise that the rendering is 'blowing'.

 

[Scousemooncat]

Evening Tony!

It looks to be a bit cyclical...the backfilling is rubbish and as a result any water has a huge impact once its in...and its let in cos of the rubbish backfilling...so its fixing the added water ingress from rain etc...and that damage caused to the brickwork etc..and re-doing the backfill and preventing the rain getting through the patio mortar etc...

Thank you for the info about the rendering - is there a way of 'decorating' the wall as it looks to be a odd brick mix (see what I mean about shoddy!)...what about a membrane that can be rendered over... Only once the inside is fixed tho clearly...

Thanks again