Concrete blocks for retaining wall

/Actually, I remember the builder explaining to me exactly how the wall was done: the holes in the blocks were aligned vertically right down to the footings and were filled with earth, with ground-cover alpine-type plants inserted one per cavity. That wall was four courses if I'm recalling it aright.

Bert /q

That was some "passing visit"....:-)

Jim K

I passed very slowly.

Bert

More seriously, it occurs to me that filling the cavities with earth would completely negate the effect of any waterproofing treatment on the inner face. And even if the cavities were concreted, wouldn't rain still soak into the top surface of the blocks (as well as soaking up from underneath, as some have said)? I suppose there would have to be coping stones of some sort.

Final thought: can you paint over bitumen paint? Suppose I coated the outer wall with that and then put conventional (outdoor/masonry) paint on top of it? The water would get into the blocks but not (perhaps) out to the visible face.

Bert

To answer my own question, a post from the archives of this very group:

"Paint the bitumous over with PVA glue 2X. This seals it in for overpainting. The cheap stuff for mixing with plaster/cement is OK. You need to leave the bitumous as long as possible first, three or four weeks ideally."

(Posted by "Harry in May 2011)

That sounds like a possible approach.

Bert

Retaining walls are always a problem. You can't put a conventional horizontal damp course in, the horizontal pressure of the earth will push the wall off of it. The benefit of a vertical damp course is to keep the plants from drying out Plain concrete blocks will do the job but look a bit s**te, especially as they get older, The best solution is some sort or concrete block with a moulded fake stone look. Anything you apply on the outside will come unstuck at some point in the future unless it is porous to let the moisture through.

The thickness of the wall should be one third of the height at the base (tapering as it goes up.). If itis more than three metres, it needs movement joints linked with slip ties to prevent random cracks appearing. Remember hydrostatic pressure is the enemy of retaining walls.

I have an earth shielded rear wall to my house. It has horizontal drains behind the footings and an inverted tee cast concrete structure (Called heel and toe or cantilevered),

Many have tried painting cellar walls with bitumen. As I said, it doesnt stop salt disfiguration & damage. As various people have said, you need a dpc on the inside. If you dont believe us go google.

NT

NT wrote, more or less:

I don't disbelieve anybody; I accept that water penetration will occur unless prevented. I'm simply exploring (and asking about) possible different ways of achieving that prevention.

Bert

That's interesting: I've been thinking so far about preventing water penetration purely because it would be detrimental to the walls - it never occurred to me that it could be bad for the plants too.

A good idea; thanks. And also for the technical details.

Ah. So a porous paint covering, assuming that such a thing exists, would be unaffected by penetrating water, assuming that I don't prevent it for whatever reason.

Bert

/Ah. So a porous paint covering, assuming that such a thing exists, would be unaffected by penetrating water, assuming that I don't prevent it for whatever reason. /q

:-)

Jim K

Actually its not bad for the blocks

I've built a 2ft+ retaining wall out of concrete blocks faced with brick. No damp course, nothing. What do you think they make foundations that are under the damp course - or indeed under water - out of?

I'd rather have the wall covered in ivy, or some other evergreen. A few back to front drainage holes at the base would be a good idea, or leave the mortar out on every other block

And the penetrating water didn't affect the adherence of the bricks to the face of the wall? That's very encouraging, given that cladding with brick or stone is one of the options I've considered. Many thanks.

Bert

lord no. I tied everything together with cavity wall ties anyway and shoved scrap mortar down the cracks

You need high quality bricks though or freezing will spall them

There were cement based paints that are allegedly micro porous. I haven't seen them for a while now.

As a cheap solution, I saw a nice retaining wall someone had built using old