HELP - Damp!

[harrassedhousewife]

we seem to have a damp problem but 1/how can i be sure (there seems to be alot of scepticism about rising damp) and 2/ if we do have it, what is the best thing to do?
it is on interior ground floor solid brick wall, worse at bottom, rises to about 1m, worse on one side but evident on both. no pipes in wall tht might be leaking, have had plumber check underfloor (wooden boards) for water pipe leaks - no evidence of. so if not a leak, is it probably rising damp? and if so, given widespred scepticism about some of dpc's - what should my next step be??
all suggestions welcome!

 

[mointainwalker]

Find your post a little difficult to understand.

Is this wall completely internal i.e. internal on both sides ?

I ask becuase you say it is brick and it is on wooden-floor-boards and I have never heard of internal brick walls ( not builder, DIYer) and then you mention DPC which is only going to be incorporated into an outside wall.

When was the house built ?

In any case , if this wall is sitting on a suspended floor i.e. on wooden-joists supporting it, with a space below them, it would be a physical impossibility for you to have rising damp. This has to come from direct contact with a damp material i.e. the ground/earth.

Using the Sherlock Holmes method of elimination, if there are no pipes in the wall and it is not sucking up water from something damp below, it can only be condensation.

What covering do you have over the brick ? Paint, wall-paper ?

P.S. Just occured to me. Are you sure it is brick i.e. reddy-colour or perhaps blocks which will be in some shade of grey with a rough surface ?

 

[RonnyRaygun]

I ask becuase you say it is brick and it is on wooden-floor-boards and I have never heard of internal brick walls ( not builder, DIYer) and then you mention DPC which is only going to be incorporated into an outside wall.

I'm not sure that she means the wall is built off the floorboards.

it is on interior ground floor solid brick wall

I think she simply means the damp is on a wall which is at ground floor level, although ambiguous I admit.

I have never heard of internal brick walls

Internal brick walls are pretty common, especially in older houses, and should have some form of DPC...

So I guess it could be rising damp...

 

[mointainwalker]

@RR

..but brick-walls off a suspended - floor ? I presume you mean off ground or slab there ?

 

[harrassedhousewife]

sorry not to be clearer!!

the wall is definitely solid red brick, with some kind of browny/gray cement/render/plaster on top (i got plumber to take off section of plaster so can see brick underneath).

it is partly external and partly internal, ie classic terraced house with full width sitting room leading on to half-width kitchen - damp wall is rear sitting room - so partly backs onto garden alleyway and partly divides sitting room from kitchen. hope that makes sense! weirdly, the damp is much more concentrated on the bit of wall that separates sitting room and kitchen - ie the internal bit - rather than bit that separates sitting room and garden - ie the external-facing section.

the house is i guess 1900. the wall brick goes down into the earth - when we took up the floor boards you can see dirt/rubble/earth -then wooden joists that my floorboards obviously rest on.

i don't know if this helps.

if it IS rising damp, any thoughts on a genuinely effective treatment? i've read alot of scepticism about chemical dpc's and feel a bit tentaive about just ringing eg Kenwoods and some salesman with a beeping geiger counter thingy coming round. have heard mixed reports about peter cox - any thoughts on them or other? on the other hand, am not really sure what else to do except put myself in the hands of one of these companies...

woody, jerry and joe, have enjoyed reading your past posts, welcome any thougths here.

 

[RonnyRaygun]

@RR

..but brick-walls off a suspended - floor ? I presume you mean off ground or slab there ?

Yeah, sorry. built off ground with suspended floors butting up to it.

 

[jeds]

I would be suprised if is was rising damp. In 15 years of surveying houses I have never really come across dampness that was not something other than rising damp.

A common problem in this situation is lack of ventilation beneath the floor which causes condensation. A second common problem is that the walls are cold beneath floor level and where the wall transitions from below floor to above (i.e the bottom 1m or so of wall) it is prone to condensation. It tends not to happen as much above 1m or so because the walls above 1m are temperature stable.

What is the depth of the void beneath your floorboards - i.e. from the floorboards to the earth sub-floor? And what is your underfloor ventilation like? Do you have plenty of vents in the front and rear walls of the house at low level?

Also what sort of plaster do you have on the walls. Is it original lime mortar or modern stuff?

 

[silurian]

Phone the condensation centre New Inn ,Pontypool for some free advice over the phone.

*******

Have a a few damp and condensation problems over the years. This guy really knows his stuff and has given me loads of advice over the phone. He has always rectified my property issues and may know someone reputable in your area who could help.

Good luch, let me know how you go.

 

[alittlerespect]

Hi

Can't help but say, if you put some photo's online people may get a better idea of the problem you are faced with! The old saying 'a picture is worth a thousand words' comes into play, but a few pictures may provide a better return!

Regards

 

[harrassedhousewife]

thanks so much all for all your thoughts!

re some more info...

the space between the floor boards and the dirt is about 10cm.
the walls have got paint, paper, plaster (can't tell how old it is, but i definitely haven't put it on in the last 10years) and under that some cementy-looking stuff which looks antediluvian, and then the bricks.
i don't know about vents, will have a look in the morning.

i don't know if this helps with whether it might be condensation. i suppose i wonder if condensation why that section of the wall and not the rest of the walls in the sitting room.

i will try to post some photos but i'm not sure you would be able to see that much - its more when you touch the wall it is really moist and clammy, and the paper/plaster is really soft to the touch (also the stuff underneath - i think its called render??? - seems very friable).

i will ring the condensation centre in pontypool - who knew it existed!! - thank you very much for that lead.

aaargh! definitely harrassed housewife at the mo...

 

[mik745]

I would say a bad case of rising damp

alot of work here,

the plaster/render on the internal wall will need to come off to aleast 1m.
If you have seen the news of ppls houses flooded you will see standard practice is to remove to that level.

The wall needs a DPC putting in, generally an injection should do the job, the wall need to be left, heres the hard part for quite sometime to be left to dry out. use a de-humidifier but slowly don't dry out to quickly.

cost around a day for the removal, injecting then you have to wait, pay for a plasterer again about a day but only when the damp has gone.

Does the wall seem wetter after rain?
Are the gutters above the area where the damp is clear?
you need to try and find the source of the damp

hope this helps.
I have just removated a house like yours and it cost £120 for a dpc kit to do the whole house with silcone based injection DPC, which is injected into the mortar

if the wall is small I would remove all the render and replaster the whole wall, it will look alot better

 

[^woody^]

So to summarise, this is a standard Victorian terrace and the damp is along the rear external lounge/diner wall, to a height of 1m, and extends sideways along the internal partition? And from inside this is effectively one wall across the back of the lounge/diner?

You need to eliminate various possible causes and determine most probable causes and then concentrate on a most likely source of the dampness.

Assuming you've discounted a leaking pipe, there is no raised external ground against the wall, and gutters are not leaking and no obvious dampness to the external wall or damaged brickwork, and no obvious bridge of any DPC

So from the lounge, if this damp is at a constant height all the way across the wall then its moisture coming up or a cold [different] material in that part of the wall causing local condensation

If the damp is higher where the wall is external and tapers off as it becomes an internal wall, then moisture coming from outside is more probable

If the damp has a definite line, nearly level, of a dark brown/yellow stain and possible some white salts, at its uppermost level, then this is more likely moisture coming up.

1m high dampness is more likely damp coming up (failed or no DPC) or condensation. It seems that you have some render on the internal wall.

This can lead to two possibilities (based on my experience of these properties)

1. This type of rendering work either hides the damp completely and it never penetrates through to be an issue, or in extreme cases damp can rise behind the render (which is typically 900mm high) and shows at about 1m high.

2. Hard render creates a colder surface from the rest of the wall and condensation forms on it. Dampness behind the render acts to cool the wall too and assists condensation, or some evaporation occurs too from some penetration of the render. The nett effect is that the band of render shows up as damper than other parts of the wall or room

Now, without a site visit or additional tests, its had to say which is occurring. The symptoms of each of these are different and need to be investigated on site, and there could be a bit of both

A test is available to drill the wall and analyse the dampness within (not just on the surface) and this can tell where the moisture is coming from. Or it may be possible to look at it and say which is more likely

If the cause is obvious and can be removed (ie leaking pipe or raised ground) then removing it will remove the damp. But if the damp is the result of a failed (or no) DPC or failed render (or end of life) then work has to be done.

Even if the cause is solely condensation, then unless you have symptoms/issues elsewhere in the property, then its not really something to be dealt with by opening windows etc, as the problem will still remain

For typical remedial work, the render will need to come off to 1m height and either re-done or a different plaster is used. At this time, either way, it may be prudent to inject a new DPC into the wall as this is a relatively small part of the cost of the whole job

 

[harrassedhousewife]

thanks so much for the replies

am moving back to thinking i do need a damp specialist (as i know its def not a leaky pipe) and don't think i'm going to be able to pinpoint the source myself.

am going to contact the chap in pontypool (i have but we've missed eachother so far) and see if he has any suggestions

if anyone else has any reccomendations for damp specialists that they trust in the london area / south east i'd be grateful for names.

thanks again!

 

[JohnD]

i know its def not a leaky pipe

do you? If so, how?

In particular, knowing that water pipes are laid in the ground, and that they do not last forever, and that they contain water that comes out through cracks and holes. how do you know that water is not coming from a pipe?

You say "the damp is much more concentrated on the bit of wall that separates sitting room and kitchen " and of course, old kitchens have taps and sinks, and correspondingly old pipes and drains.

 

[harrassedhousewife]

well, i had a plumber round

first he took a look at the central heating pipes which run behind the door architrave (the door between my sitting room and kitchen). they were my prime candidate bec they run floor to ceiling up the side of the door RIGHT BESIDE where the damp is on the wall (they go up to the second floor). but no sign of wetness, not a drop, around them.

then he took up the floor board boards in the sitting room to have a look at the various pipes - there were water pipes that run the length of the sitting room from i guess the mains outside, and also more central heating pipes feeding the various radiators in the sitting room) - again, no discernable leaks. he felt the earth beneath the floorboards (about 5-10 c beneath the floor boards) and said it did seem slightly damp, and also that there was a fair bit of rubble down there, but no sign of a leak that he could find. so i guess that's not conclusive, but as good as i've been able to do so far.

he did say the water mains stopcock outside the front of my house (in the pavement) was flooded, and i have called the waterboard but so far haven't been able to get them round, as its not so badly flooded that its visible from pavement or anything. no idea if that could be a factor or not, will keep pursuing them