Rising damp please help??

[Keiran]

Hey all,

As subject says i suspect i have rising damp??....

It's manly on the party walls, which i find a bit strange but hey...

I have dug away a bit of the plaster at the bottom of one of the walls, to reveal what looks like an old skool tanking membrane... looks like a roofing felt material corrigated type stuff??

The damp is typically showing just over a metre up the walls (so suspect that is where they stopped with previous tanking), and it is really not pretty... apart from where there have been fixings drilled into the walls at a lower level in the past where we are getting the odd spot of damp...

So... I have had two companys come in and quote for reapair and a damp surveyor, and they have all suggested tanking the walls with damp proof membrane straight over existing palster, then dot and dabbing fresh plaster board over that as they suspect it is mainly salts?? But does get really wet...

Does anyone have experience with this problem and can give any suggestions as to the best way forward?

We are on a very tight budget, so am thinking of tackling this myself, i am very practical and have succesfully tackled many home improvement projects in the past, and am an electrician so no stranger to building projects and the like

I was considering injecting a dpc, but just can't make my mind up?

If i tank... will wall not just stay damp behind and fester? (do i need to batten to leave air gap or?

Will dpc injection be best? (is it ok to do from inside? was thinking in the first showing mortar line?)

They are only single skin brick walls, house is mid terraced approx 100yrs old.

Any help would be greatly appreciated, as i really need to get on top of this unsightly damp once and for all

Thanks in advance

Keiran

 

[foxhole]

You need to trace the source of the damp, or you are throwing money away.
Definitely not rising damp.

 

[Keiran]

Yeah... that's what i suspected might be the case, wondered whether it was storm drains or something but can't get plans of drainage or anything from anyone??

 

[Flyboytim]

This problem is becoming so common this autumn - it is a hangover from the drenching we got last winter - now the ambient temperature is dropping to near or below the dew point, the walls are sweating where they have absorbed atmospheric water, and are cooling through evaporation. A surveyor I spoke to recently said that it can take a couple of years for a building to dry out properly.

It's a vicious circle that cannot be broken with heating, unless you have radiant or conducted heat directly warming the walls. Central heating warms the air, increasing its capacity to hold water, and that condenses on your cold, lower walls.

To stop this you need the walls to be kept at the same temperature as the ambient air while they dry out.

A standard desk fan (40 odd watts) pointed at the walls for a few days will help the evaporation while keeping the walls at the same temperature as the air blowing over them, counteracting the evaporative cooling. If the fan is oscillating, it will cover a greater area of wall. A dehumidifier is probably a waste of money.

It is better to control your heating by thermostat, rather than with a timer - set your heating low and constant at about 15 C only raising to about 18 C, and do not turn it off - otherwise, most of the heat will be countering the evaporation of the walls for the first couple of hours when you turn it on.

Don't ventilate with the outside on wet days, only dry ones. A cold dry day will have much less moisture in the air than a warm dry day, so will aid removal of moist air from the house.

Tanking has a specific purpose - to act as a barrier to a permanently wet wall behind the dry interior surface. If you drill a pilot hole into the wall and dust comes out it is not wet. If wet, the drill will come out clogged with mud and steaming.

 

[gregers]

if you inject the party walls(9"thick) you will only drill and inject 4",which leaves your neighbours 4" wall untreated,so injecting is a waste of time because it will bridge over the injection.

 

[Keiran]

I think the wall is only 4"thick Single skin brick from what I can work out...

 

[gregers]

really for a party wall?
bet thats noisy?

 

[Keiran]

It's not to bad now we got new neighbours, but with the old ones it was a bit noisey =) Does that sound odd then? Do u think it's more likely 9"?