If I build a raised flower bed using dense concrete blocks it is advisable
to paint or otherwise treat the inside surfaces before filling with earth?
Many thanks.

On 12/08/14 16:34, Bert Coules wrote:
If I build a raised flower bed using dense concrete blocks it is
advisable to paint or otherwise treat the inside surfaces before filling
with earth? Many thanks.

Totally unnecessary. Concrete blocks of exterior grade are happy to go
under the soil


--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll

"Bert Coules" wrote in message
o.uk...
If I build a raised flower bed using dense concrete blocks it is advisable
to paint or otherwise treat the inside surfaces before filling with earth?
Many thanks.

The problem is there is a lot of water loss by evaporation through the
blocks.
You can stop this by painting the inside with bitumous paint or lining with
polythene.
Also reduces frost damage if the blocks are dryer.

I hope you have left "weep holes" at intervals for drainage.
http://en.wikipedia.org/wiki/Weep_hole

/The Natural Philosopher
- show quoted text -
Totally unnecessary. Concrete blocks of exterior grade are happy to go under the soil /q

Perhaps but if the OP is planning to paint or render the outside of the retaining wall he would do well to address the penetrating damp issues that will occur..... BTDTGTTS

Jim K

Thanks to everyone for the replies.

JimK wrote:

Perhaps but if the OP is planning to paint or render the outside
of the retaining wall he would do well to address the
penetrating damp issues that will occur...

I have no definite plans as yet, but painting the outside is something I've
thought about. With no internal treatment, does the penetrating damp
affect even specialist masonry paint?

Bert

On Tuesday, August 12, 2014 10:21:21 PM UTC+1, Bert Coules wrote:
Thanks to everyone for the replies.
JimK wrote:

Perhaps but if the OP is planning to paint or render the outside
of the retaining wall he would do well to address the
penetrating damp issues that will occur...

I have no definite plans as yet, but painting the outside is something I've
thought about.

FAIL.


NT

FAIL.

I have absolutely no idea what that is meant to convey.

Bert

"Bert Coules" wrote in message
...
Thanks to everyone for the replies.

JimK wrote:

Perhaps but if the OP is planning to paint or render the outside
of the retaining wall he would do well to address the
penetrating damp issues that will occur...

I have no definite plans as yet, but painting the outside is something
I've thought about. With no internal treatment, does the penetrating
damp affect even specialist masonry paint?

Bert

The paint will be lifted off the wall by water pressure.
It's not possible to fix this as there will aso be a "rising damp" issue,

If you want something that looks decent you will have to use other than
concrete blocks and unpainted.
It would be best frost resistant too.

"harryagain" wrote:

The paint will be lifted off the wall by
water pressure. It's not possible to fix this
as there will also be a "rising damp" issue,

Ah, so even if I treat the inner face of the wall, water will soak up from
the base through the footings?

If you want something that looks decent you
will have to use other than concrete blocks and unpainted.

What about blocks covered on the outer surface by some sort of facing?
Stone slips, thin bricks, that sort of thing, fixed with waterproof adhesive
rather than mortar?

Thanks for the thoughts.

Bert

On 13/08/2014 00:05, Bert Coules wrote:
FAIL.

I have absolutely no idea what that is meant to convey.

Bert


It's a way of attracting attention. Just IGNORE :-)

/ JimK wrote:

Perhaps but if the OP is planning to paint or render the outside of the retaining wall he would do well to address the penetrating damp issues that will occur...

I have no definite plans as yet, but painting the outside is something I've thought about. With no internal treatment, does the penetrating damp affect even specialist masonry paint?/q

IME yes, more than once! This was a weak mix rendered retaining low garden block wall (by others...) and it progressively looked mouldy, flaky, blew parts off after frosts & was generally a bit crap. Annual painting with proper stuff did not provide a solution. I "roofed"it in red cedar shingles in the end.

Jim K

"JimK" wrote:

...and it progressively looked mouldy, flaky, blew parts
off after frosts & was generally a bit crap. Annual painting
with proper stuff did not provide a solution. I "roofed"it in
red cedar shingles in the end.

Ah, that's interesting, thanks Jim: cladding the outside is something I've
considered (both on this new wall and the existing one that I mentioned in
an earlier thread). So whatever you used to fix the shingles (mortar?
adhesive?) wasn't affected by the penetrating damp?

Bert

I wrote:

So whatever you used to fix the shingles (mortar? adhesive?) wasn't
affected by the penetrating damp?

On reflection, did you fix battens and nail the shingles to them? ("Roofed"
you said.) Stupid of me not to think of that.

Bert

On Wednesday, August 13, 2014 12:05:04 AM UTC+1, Bert Coules wrote:

FAIL.

I have absolutely no idea what that is meant to convey.

What you proposed will fail. No paint is going to stop evaporation adn thus salt crusting. If you want it to stay looking decent you need a waterproof layer on the inside.


NT

/Ah, that's interesting, thanks Jim: cladding the outside is something I've
considered (both on this new wall and the existing one that I mentioned in
an earlier thread). So whatever you used to fix the shingles (mortar?
adhesive?) wasn't affected by the penetrating damp/q

Nah stainless steel screws into plugs in wall, with breathable roofing membrane between wall & shingles...

You need to include a vertical dpm or somesuch in your wall construction to hopefully avoid all that!

Good drainage under the raised bed, and some good dpm lining the 'back' of the wall, lapping a bit away from the wall at the base to 'steer' moisture away from the blockwork?
You can get black dpm if you look about, rather than green or blues that seem to prevail.


Or how about a vertical layer of gravel to form a French drain around the inside of the wall??

Coping stones to reduce rain penetration from above maybe laid with mortar mixed with a waterproofer for belt & braces!?!

Jim K

Thanks for the explanation.

Bert

Jim, thanks for the detailed reply. One of the possibilities I considered
(I've seen something like it done elsewhere) is to use those blocks with
square holes ("Hollow blocks" are they?), fill the vertical cavities with
soil and put ground-cover plants along the tops of the walls so they could
trail down the outside, ivy-like. Under those circumstances the dampness of
the outer surface might be a positive benefit, but I don't know just how
much coverage of the vertical blockwork I could expect to achieve: any areas
of bare blockwork that were left exposed might still look fairly raw and
unattractive.

Bert

/One of the possibilities I considered
(I've seen something like it done elsewhere) is to use those blocks with
square holes ("Hollow blocks" are they?), fill the vertical cavities with
soil and put ground-cover plants along the tops of the walls so they could
trail down the outside, ivy-like/q

How high a wall we talking?
Those hollow blocks are intended to have rebar through them to stitch courses together and then filled with concrete... not sure how strong the wall would be if blocks filled with damp soil, nor what would happen in winter wrt spalling etc?

Jim k

"JimK" wrote:

How high a wall we talking?

Three courses: something like 26 inches overall height. I understand the
objections, but as I say, I have seen it done - though that was only a
passing visit and I've no idea of its success or otherwise long-term.

Bert

/Three courses: something like 26 inches overall height. I understand the
objections, but as I say, I have seen it done - though that was only a
passing visit and I've no idea of its success or otherwise long-term. /q

Or its' construction maybe? Might you have viewed those blocks 'end on' perhaps? As part of a much deeper & more usual hollow block retaining wall construction?

Just a thought:-)

Jim K

"JimK"wrote:

Or its construction maybe?

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

/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

"Bert Coules" wrote in message
o.uk...
"harryagain" wrote:

The paint will be lifted off the wall by
water pressure. It's not possible to fix this
as there will also be a "rising damp" issue,

Ah, so even if I treat the inner face of the wall, water will soak up from
the base through the footings?

If you want something that looks decent you
will have to use other than concrete blocks and unpainted.

What about blocks covered on the outer surface by some sort of facing?
Stone slips, thin bricks, that sort of thing, fixed with waterproof
adhesive rather than mortar?

Thanks for the thoughts.

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 ****e, 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),
http://en.wikipedia.org/wiki/Retaini...l#Cantilevered
Thw damp course is vertical and then hosizontal out into the earth.
Plus there is an injected chemical into the lower part of the wall
Bit elaborat e for a garden wall.

On Wednesday, August 13, 2014 3:27:05 PM UTC+1, Bert Coules wrote:

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

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:

If you don't believe us, go Google.

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

"harryagain" wrote:

The benefit of a vertical damp course is to keep the plants from drying
out.

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.

The best solution is some sort or concrete block with a moulded fake stone
look.

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

Anything you apply on the outside will come unstuck at some point in the
future unless it is porous to let the moisture through.

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

sits back and waits for annual real lime whitewash suggestions.... :-)

Jim K

On 13/08/14 20:41, Bert Coules wrote:
"harryagain" wrote:

The benefit of a vertical damp course is to keep the plants from
drying out.

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.


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?



--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll

On 13/08/2014 20:50, JimK wrote:
/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

sits back and waits for annual real lime whitewash suggestions.... :-)

Jim K


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

The Natural Philosopher wrote:

I've built a 2ft+ retaining wall out of concrete blocks faced with brick.
No damp course, nothing.

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

On 13/08/14 22:24, Bert Coules wrote:
The Natural Philosopher wrote:

I've built a 2ft+ retaining wall out of concrete blocks faced with
brick. No damp course, nothing.

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


--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll

"Bert Coules" wrote in message
...
"harryagain" wrote:

The benefit of a vertical damp course is to keep the plants from drying
out.

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.

The best solution is some sort or concrete block with a moulded fake
stone look.

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

Anything you apply on the outside will come unstuck at some point in the
future unless it is porous to let the moisture through.

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.


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
2" concrete paviours he'd cut up with hammer and chisel. The cut edges
looked (a bit) like stone.
He was able to put wide ones at the bottom and narrower ones at the top.
The attraction was they were free. But it took him forever.

"The Natural Philosopher" wrote:

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

I realised you probably did something of the sort just as I posted the
question. Thanks for confirming it.

Bert

"harryagain" wrote:

As a cheap solution, I saw a nice retaining wall someone had built using
old 2" concrete paviours he'd cut up with hammer and chisel. The cut edges
looked (a bit) like stone.
He was able to put wide ones at the bottom and narrower ones at the top.
The attraction was they were free. But it took him forever.

I have wondered about something of the sort. I have the time but not the
access to free materials though, unfortunately.

Bert

On Wednesday, August 13, 2014 3:42:09 PM UTC+1, Bert Coules wrote:
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

I've got a good example of this spalling that only this thread could explain. We've got a brick extension to a stone walled house.

About 12" from the stonework is an opening for a door; on the extension side of this door the paint over cement facing is fine whereas the stone wall side the paint after 25 years is in poor condition and the cement facing is spalling. I'm guessing that water is coming out of the stone and tracking along.

Rob

Rob,

Thanks for that. It certainly sounds as though water penetration through
the stone is causing the problem. Clearly I'm going to have to consider
this very carefully.

Bert

On 18/08/14 15:11, Bert Coules wrote:
Rob,

Thanks for that. It certainly sounds as though water penetration
through the stone is causing the problem. Clearly I'm going to have to
consider this very carefully.

Bert

proper high density blocks are sufficiently waterproof to be OK

For mortar add a bit of PVA, that reduces absorbtion

Finally if facing with brick use real quality ones - once again these
wont act like sponges

Seriously, mine is N facing and sopping wet in winter and hasn't spalled
at all.



--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll