Render below damp course

Render was probably breeching the damp course hence it's removal.

 

Chop bricks out and replace?

 

We had an old 1930's house once that had a damp problem. The render was applied at lower level as a solid, thick , smooth finish to 1 brick above dpc, where it then turned to thinner pebbledash.

The render over the years cause damp bridging, with quite severe damp in places. Just hacked off the solid, smooth part, exposing the perfectly good slate dpc and formed a bell cast drip to the bottom of the pebbledash, 1 brick above dpc. damp problem solved.

That's probably what has been done in your house.

Where I am now, new build house with roughcast render to 6" above dpc, then smooth render below to ground level. Yes you guessed it's bridging the dpc. I questioned it at the time with the builder, but that's what they do up here. It probably is storing up trouble for the future. The only difference is the new house is cavity wall (the old was was solid 9" wall) so I guess any damp bridging will go undetected longer.

In your case perhaps if you finished the "upper" render with a bell cast exactly in line with the dpc, then rendered below seperately, there would be a tiny gap which might be enough to stop damp bridging?

 

We had an old 1930's house once that had a damp
problem. The render was applied at lower level as a
solid, thick , smooth finish to 1 brick above dpc,
where it then turned to thinner pebbledash.

The render over the years cause damp bridging, with
quite severe damp in places. Just hacked off the
solid, smooth part, exposing the perfectly good slate
dpc and formed a bell cast drip to the bottom of the
pebbledash, 1 brick above dpc. damp problem solved.

That's probably what has been done in your house.

Where I am now, new build house with roughcast render
to 6" above dpc, then smooth render below to ground
level. Yes you guessed it's bridging the dpc. I
questioned it at the time with the builder, but
that's what they do up here. It probably is storing
up trouble for the future. The only difference is the
new house is cavity wall (the old was was solid 9"
wall) so I guess any damp bridging will go undetected
longer.

In your case perhaps if you finished the "upper"
render with a bell cast exactly in line with the dpc,
then rendered below seperately, there would be a tiny
gap which might be enough to stop damp bridging?

This will cause a debate ,so the 1930s house had a damp problem and the wall was a solid 9in , you obviously feel if a wall is rendered it will keep out the water , it wont ,remove the render problem solved , probably just lucky , if the wall was 9in then the whole wall would have been damp .Now the bridging on a cavity wall, surely if its a cavity wall it wont affect the inside wall so render down as far as you like , I have seen builders who hang the dpc out 10mm to allow for render to stop them bridging the damp , it looked awful and not required ,this debate came up last week to cut out a slot for shingle and I stated then thats not a problem if its a cavity wall .The render is the same if the cavity is clear then how does the damp travel across, we will debate this later and hopefully reach a good conclusion , please dont quote building regs as this is an easy way out , good luck

 

We had an old 1930's house once that had a damp
problem. The render was applied at lower level as
a
solid, thick , smooth finish to 1 brick above dpc,
where it then turned to thinner pebbledash.

The render over the years cause damp bridging,
with
quite severe damp in places. Just hacked off the
solid, smooth part, exposing the perfectly good
slate
dpc and formed a bell cast drip to the bottom of
the
pebbledash, 1 brick above dpc. damp problem
solved.

That's probably what has been done in your house.

Where I am now, new build house with roughcast
render
to 6" above dpc, then smooth render below to
ground
level. Yes you guessed it's bridging the dpc. I
questioned it at the time with the builder, but
that's what they do up here. It probably is
storing
up trouble for the future. The only difference is
the
new house is cavity wall (the old was was solid 9"
wall) so I guess any damp bridging will go
undetected
longer.

In your case perhaps if you finished the "upper"
render with a bell cast exactly in line with the
dpc,
then rendered below seperately, there would be a
tiny
gap which might be enough to stop damp bridging?

This will cause a debate ,so the 1930s house had a
damp problem and the wall was a solid 9in , you
obviously feel if a wall is rendered it will keep out
the water , it wont ,remove the render problem solved
, probably just lucky , if the wall was 9in then the
whole wall would have been damp .Now the bridging on
a cavity wall, surely if its a cavity wall it wont
affect the inside wall so render down as far as you
like , I have seen builders who hang the dpc out 10mm
to allow for render to stop them bridging the damp ,
it looked awful and not required ,this debate came up
last week to cut out a slot for shingle and I stated
then thats not a problem if its a cavity wall .The
render is the same if the cavity is clear then how
does the damp travel across, we will debate this
later and hopefully reach a good conclusion , please
dont quote building regs as this is an easy way out ,
good luck



So putting in a dpc in the outer leaf on a house with cavity, although having been done for many many years, is a totally pointless excercise, including damp-roof injecting, and including renewing dpc at any time whatsoever ? So it serves NO purpose ?



Mr. HandyAndy - really

 

Agree that this would be a pointless task, would have thought at least covering the DPC would be "Bad" practice. I cant see what good it would do to allow damp to travel up the wall regardless of whether its actually going to breach the internal walls. I have rendered walls where the ground was allowed to get to much height by previous owners and the render on the lower part of the wall is not in as good a condition as the areas where there has been no breach.
Personally I wouldn't cover the DPC.
AW

 

I would say that a solid 9" wall can have many different types dpc i.e bitumen, slate injected etc, but if they fail in any way, then damp will more than likely be caused by this failure. So rendering over the dpc may not cause any problem of its own whatsoever. But it might. So is it worth taking the chance, ABSOLUTELY NOT! Bell drip bead at least 1 course above dpc then bitumen paint on the remaining brickwork down to ground level.

Cavity walls, if the brickie has done a decent job their wont be any bridging in the cavity to cause any dampness by cappillary action , so yes, it would in theory be no problem to bridge the dpc with render. I guess that with the chance of the cavity being bridged and history of dampness problems causing a lot of hassle, it is still frowned upon to do it.
???

 

So putting in a dpc in the outer leaf on a house with
cavity, although having been done for many many
years, is a totally pointless exercise, including
damp-roof injecting, and including renewing dpc at
any time whatsoever ? So it serves NO purpose ?

Thats a good point andy, what purpose does it have , yes it stops the damp rising from below ground , but if its an outside wall does it matter , lets say you didn't put one in , what damage would it do , the outside wall would be damp any way , why put one in a garage when its single skin , the wall will be damp any .If you used engineering bricks below dpc they will not soak the moisture even to reach the damp , so render below dpc , look around and you will see

 

.

Cavity walls, if the brickie has done a decent job
their wont be any bridging in the cavity to cause any
dampness by capillary action , so yes, it would in
theory be no problem to bridge the dpc with render. I
guess that with the chance of the cavity being
bridged and history of dampness problems causing a
lot of hassle, it is still frowned upon to do it.
These days with brickies they shouldn't block the cavity at ground level , with celotex fixed to the inside theres a good chance , full fill is a better option as when the facework is built and cleaned off the insulation is placed and the blocks are laid against it , a good brickie will leave no mortar to cause any breach

 

Absolutely agree Deacon but as we all know, there are a lot of sloppy workmen out there trying to lay as many 1000's as possible not giving a **** about what will happen in a few years time due them bodging it and scarpering. I know you said not to mention it, but are there actual regulations concerning reendering bridging the dpc? Serious question because i've not come across rendering any new builds personally so don't know.

 

> other ideas on how I could tidy this brickwork up in
some way.



do like someone's already suggested...remove all old bricks (one at a time...) and replace with engineering bricks (the glazed type)

 

Absolutely agree Deacon but as we all know, there are
a lot of sloppy workmen out there trying to lay as
many 1000's as possible not giving a **** about what
will happen in a few years time due them bodging it
and scarpering. I know you said not to mention it,
but are there actual regulations concerning
reendering bridging the dpc? Serious question because
i've not come across rendering any new builds
personally so don't know.

Don't mention the dreaded regs,we are in the process of building a bungalow were the render is from ground level to dpc level on top of the dpc facework begins , it overhangs the blockwork 20mm to accommodate the rendering , the height of the render is 450mm ,why is this , its to lift the bungalow above the flooding area,so render does start below dpc , its not my idea so if the are regs to avoid this why have we just done it

 

Sounds like one hell of a long way round, must be regs or a stoned architect??!!

 

do like someone's already suggested...remove all old
bricks (one at a time...) and replace with
engineering bricks (the glazed type)

Lets say that all the bricks below dpc are affected are we to remove them all, no ,it was probably rendered and maybe some has fell off , someone decided to remove all ,his options are very limited removing the defective bricks I feel is not one them

 

Sounds like one hell of a long way round, must be
regs or a stoned architect??!!

It went through and we just do as we are told , regs , don't mention them

 

clean off old mortar best you can and slap on the bitumen, its surprising what the black stuff will hide! Easy way out I know, but I think the finish of replacing one bick at a time will end up about as good as it is now.

 

Well, I'll tell you deacon, why there is a dpc, and why you should not render over, down to floor level.

It is because bricks(normal house bricks) are not designed to be permanently wet, and the dpc prevents this.

Rain on the bricks(it is said) will never keep the bricks wet, because of the in-between spells of dry weather, where the bricks will dry out.

In the absence of a dpc, the bricks may soak up ground moisture, and continue forever to soak moisture up. This moisture will carry on rising and increasing, reaching anything that is attached to the outer skin, like wall ties, window sills etc

Likewise, the render will do the same, so forever soak water into the bricks.

They will never dry out fully.


With the dpc intact, and nothing bridging it vertically, the bricks will dry out, which is the whole point of the design.



Mr. HandyAndy - really

 

Well, I'll tell you deacon, why there is a dpc, and
why you should not render over, down to floor level.
It is because bricks(normal house bricks) are not
designed to be permanently wet, and the dpc prevents
this.
Rain on the bricks(it is said) will never keep the
bricks wet, because of the in-between spells of dry
weather, where the bricks will dry out.
In the absence of a dpc, the bricks may soak up
ground moisture, and continue forever to soak
moisture up. This moisture will carry on rising and
increasing, reaching anything that is attached to the
outer skin, like wall ties, window sills etc
Likewise, the render will do the same, so forever
soak water into the bricks.
They will never dry out fully.
With the dpc intact, and nothing bridging it
vertically, the bricks will dry out, which is the
whole point of the design.
Mr. HandyAndy - really

Whilst everything you say is correct , or so it seems ,what about my problem , my bungalow is rendered from dp.c level down to the ground , facework above dpc explain that .Now render over the dpc .so damp travels up from the ground through the render , over the dpc and in above the dpc , it then travel across the cavity and in to the house , no ,and what about the 1000s of house now that are rendered below dpc and is there , I didnt want to mention , building regs to confirm you dont bridge the dpc with render , explain this

 

Well you can take out a few bricks at a time, relay some semi or full engineering bricks to existing levels. Do in sections. Bitcho always looks good tho.