green stains on exterior walls
IC
external rendered wall. Is this sort of thing likely to be caused by
blocked guttering? The stains start at the roof and extend down a
couple of metres before fading out.
To bring it on-topic, can anyone recommend somebody to have a look at
it and/or sort it out? Don't have a long ladder myself.
Cheers
Ian
Duncan Wood
> After the recent cold weather, we've been left with green stains on an
> external rendered wall. Is this sort of thing likely to be caused by
> blocked guttering? The stains start at the roof and extend down a
> couple of metres before fading out.
>
Sounds like a blocked gutter
The Natural Philosopher
lichen.
Pressure washer.
caused by a lot of surface damp. You should see my camper..
Ben C
> IC wrote:
>> After the recent cold weather, we've been left with green stains on an
>> external rendered wall. Is this sort of thing likely to be caused by
>> blocked guttering? The stains start at the roof and extend down a
>> couple of metres before fading out.
>>
>> To bring it on-topic, can anyone recommend somebody to have a look at
>> it and/or sort it out? Don't have a long ladder myself.
>>
>> Cheers
>> Ian
>
> lichen.
>
> Pressure washer.
What's actually wrong with it? Why not just peacefully co-exist with the
stuff? After all it's fashionable to be "green" these days.
The Natural Philosopher
unsightly that's all.
Or it may reveal an underlying damp problem caused by something else.
Ben C
Which blasting with a pressure washer isn't going to solve. If anything
the lichen will actually suck some water out of the walls leaving a
drier habitat inside.
However since OP says they start at the roof it sounds like it's just
rain falling down the side of the house rather than moisture seeping
upwards from the unwholesome fens below.
Jon Green
> IC wrote:
>> After the recent cold weather, we've been left with green stains on an
>> external rendered wall. Is this sort of thing likely to be caused by
>> blocked guttering? The stains start at the roof and extend down a
>> couple of metres before fading out.
>
Far more likely to be algae.
> Pressure washer.
NO-NO-NO! It's a _rendered_ wall, remember? There's a serious risk
that a pressure washer could cause significant and expensive damage to
the render.
Do check the guttering first, otherwise any other fix will be distinctly
temporary.
Once you've got that sorted, and fixed the root cause -- and when you've
a dry spell to give it a chance to work -- algicide would seem a
sensible approach. When that's done its job, it's time to repaint, or
(carefully) surface-scrub to remove the stains.
Jon
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with 'green-lines'.
Duncan Wood
If it falls of when you point a domestic pressure washer at it then it was
fairly crap in the 1st place. Anyway I suppose I can be pub;ic;y spirited
publicly spirited & ask which end of Cambridge as I need to move the large
ladder next week?
magwitch
Our house is rendered and I use the pressure washer on it whenever
necessary without incurring any damage (the render's approx 10 years old).
If the render's fragile enough to be damaged by a domestic pressure
washer then that's a more serious problem than the algae... more likely
to be damp behind the render causing it to lift off.
Duncan Wood
Exactly. You can cyt throug rebder with teh ultra high ppressure curcimh
spots on a modern pressure washe, but if you've got green stains below the
gutter then cleaning the gutter's oing ton be cheaper than rerendering the
house.
The Natural Philosopher
IN my case its nothing more than straightforward driving rain. Where it
happens is a function of less ventilation and less sun, that's all.
The Natural Philosopher
> On 31/12/2009 18:45, The Natural Philosopher wrote:
>> IC wrote:
>>> After the recent cold weather, we've been left with green stains on an
>>> external rendered wall. Is this sort of thing likely to be caused by
>>> blocked guttering? The stains start at the roof and extend down a
>>> couple of metres before fading out.
>>
>> lichen.
>
> Far more likely to be algae.
>
>> Pressure washer.
>
> NO-NO-NO! It's a _rendered_ wall, remember? There's a serious risk
> that a pressure washer could cause significant and expensive damage to
> the render.
>
Almost none. I routinely clean my render with a pressure washer.
The first thing that would happen if anything did, would be lifting of
the paint. If that happens, back off a foot .
It takes a lot less pressure to lift lichen, than to lift render, I can
assure you.
The Natural Philosopher
Good party?
anyway, if the pressure washer lifts the render, it needed re rendering
anyway.
Lichen appears anywhere its persistently damp. That may or may not
indicate a guttering problem.
ALL my vehicles parked outside suffer from it, as does the complete
north facing tiled roof, most of the guttering interiors, the north
facing steel garage doors, and parts of the north facing walls and
window frames..
Oh, and parts of the patio. Except that's red and black gunk. That may
actually be algae though.
Jon Green
> Exactly. You can cyt throug rebder with teh ultra high ppressure curcimh
> spots on a modern pressure washe
*boggle* That's either a language I'm not familiar with, or you need to
stop typing with your ear!
Paul
> On 01/01/2010 03:51, Duncan Wood wrote:
>> Exactly. You can cyt throug rebder with teh ultra high ppressure curcimh
>> spots on a modern pressure washe
>
> *boggle* That's either a language I'm not familiar with, or you need to
> stop typing with your ear!
>
> Jon
I thought the funnier part was where he was commented on by TNP who is
traditionally the worst offender.
PB
IC
On further inspection today in better light, I now think the stains
are yellow rather than green. So might be water damage rather than
algae.
We have no overhanging trees, so I wonder if the gutter might have
filled with ice over christmas, and overflowed with snow melt and
rain.
Anyway, I'll check the gutter, clean the wall if possible, and see if
it recurs.
Cheers.
IC
stuff running the length of the gutter. Probably not melting because
of the temperature at the fact that it's an east-facing wall.