How can I stop damp coming through wall?

[JohnD]

Rods don't work. Silicone doesn't work. If you have a damp hearth, ventilation will help some of the moisture evaporate away. If the old fireplace is full of builders rubble it will hold damp.

The successful solution is to reopen the chimneybreast, break the hearthstone and dig out the damp rubble beneath, dig it out by a foot or so (if you look under the floorboards you will see the height of the earth or concrete under the house), preferably to the level of the oversite.

You can put an airbrick sized hole just above the skirting for ventilation, with an ornamental grille.

If you have a suspended wooden floor with a ventilated space beneath, then when you dig out the old hearth, you can open the cavity to the underfloor space, and this will enable the floorspace to ventilate up the chimney. I think this is a good way to ventilate away damp, and it means you do not create draughts inside the room. In fact, if you have an open fire or a stove still in use, you can put a brass grille in the floor allowing the fire to draw air from the void, to combat draughts that a fire normally causes. You sometimes see this in high quality houses from Victorian and older times.

 

[Gary111]

Thanks very much for your detailed reply. I'll do that.

 

[Gary111]

When you say rods don't work do you mean just for a fireplace or that they don't work in general?

Thanks

 

[JohnD]

in general

However I have got some magic beans I can sell you.

 

[Gary111]

Haha, ok, what's best for any other walls that are damp at the bottom in that case please?

 

[JohnD]

Find where the water is coming from, and repair the source. It is often a leaking drain or pipe, sometimes a spilling gutter, sometimes earth or paving heaped up against the wall over the DPC or holding puddles or rainwater against the wall.

Or, indoors, in winter, often condensation. In UK the worst cause is wet washing draped around the house, followed by steamy showers without an effective extractor. It can be caused by a leak, including pipes in or under the floor and not visible.

Breathing and sweating in bed are easily rectified by opening a window.

 

[Gary111]

Thanks for your help, it seems to be all the external beaded corners going up to around 2/3 feet from the floor.

It's on the internal walls also.

Is there any way to tell if its just condensation or something more serious?

Thanks

 

[Gary111]

Also I have a bit of mapei shower tanking membrane spare, maybe if I paint over the corners with that it will seal in the rust?

 

[Koolpc]

Salts can be an issue on old fireplaces. Its not easy to eradicate as they can be leeching through the brick / stone.

 

[Gary111]

It's not just in the fireplace though, it's the other walls too

 

[JohnD]

Thanks for your help, it seems to be all the external beaded corners going up to around 2/3 feet from the floor.

It's on the internal walls also.

Probably soaking up from the ground then.

Have you found the DPC? How far above ground level is it?

Is it a concrete floor?

Show us your wider photos inside and out

Draw a ground plan of the house

Mark the damp patches

Show the position of drains, downpipes, sinks, taps, and the stopcocks that give clues of buried waterpipes.

 

[Gary111]

Thanks, it's mainly wooden floor, with a concrete floor to the back room.

There are no air bricks under the concrete part.
There is half a buried air brick, a small section also has chemical injection type holes.
I can see part of a dpc on a newer section, but cannot see a dpc anywhere on the rest of the house.

If I dig into the surface mortar I get soft black mortar.
The house is around 1900

 

[Gary111]

 

[JohnD]

It looks like there is a source of water along that wet wall by the drain pipe

And it looks like the concrete against the wall is too high and bridging the DPC. The DPC was probably below that doorstep.

Please take some wider pics showing the entire wall, all the way up to the gutter and downpipes, and all the way down to the ground and paving. Show all pipes, drains, gullies and manholes.

Also draw that ground plan.

The soft black stuff between the bricks might be mud. Hose it out.

 

[Gary111]