DAMP decision

[yamato]

@Yamato - FFLS = Finished Floor Levels.

Can you do a sketch (this is a quick eg in MS Paint):

Untitled

• Justin Passing
• 25 Aug 2014
• 1

to show relative levels of the floor, drive, height where "damp" is showing, any original damp course eg in green here (look at the front/rear of your house, where you may see it), etc. Plus any replastering that's been done, or anything else relevant.

I'd worry about the drain in the drive. As you've removed the contents, can you see where the water goes? Tip some in, does it disappear?


@the experts - exactly what qualification should someone look for when selecting a consultant on damp problems. It seems to be a minefield.

Hey Justin.

so the situation is pretty similar to your drawing

View media item 85652The red circle is the damp which is above the line of the damp proof course. I feel this is just damp rising above it.

actually though the drive is on a slope and the neighbours drive just gets higher and higher the further back you go. I've noticed there is a even a flower bed against the wall which means that in my outhouse the ground level is terrible high. What is about 6 bricks from the floor in the outhouse is only about 2 bricks above the flower bed level.

The door frames in the middle of the house getting particularly wet. This is about at the line where the block paving was added outside.

the neighbour gave permission for a drain to be added down the side of my house and I'm very tempted to do it (even though I would pay). I haven't asked him if he would be willing to remove the flower beds though...that could be more difficult.

 

[theprinceofdarkness]

A lot of good advice here!
As built the DPC would have been at least 6" above the ground level, so "rising damp" would have had a chance of drying out before its even reached the DPC. I think this situation should be restored. The problem is much worse here as the water that runs down the drive will actually be soaking directly into the side of the wall above the DPC. So I would be dig a drain down the side of the house and fill it with compacted pea shingle, to keep the integrity of the drive, up to within 2" of the DPC, then cap it with a perforated drain. The depth of the pea shingle should be at least 6" and it would be nice if it could have a slight slope on it so if it were to become flooded, the water would run beyond the house.
This would restore a small amount of ventilation below the DPC, and any surface water would drop down to below the DPC. It would also offer a small amount of drying out to the soil adjacent to the house.
I would soak the bottom 12" of the wall with a water repellent silicone base fluid to prevent splash back water getting into the brickwork.
Frank

 

[jeds]

You have everything going on there and the problem is most likely a combination of factors. In those situations the only option is to start from the top and work on a process of elimination. First check the roof. Water entering at the top can seep down the collar joint (between the bricks) and spread lower down. Second check absorption and evaporation of the wall. Analyse samples of mortar at various heights up the wall or use test sticks. The analysis will show if the wall is truly damp and how that dampness changes at different levels. Analysis of salts and nitrates in the mortar can also identify whether it is penetrating or rising. Third, I would also want to look under your floor. Lift a floorboard somewhere against the wall. Make sure your cross ventilation is good and clear and make sure you don't have water pooling underneath.

You could do some of this yourself. There are test strips and sticks available that will accurately tell you if dampness is actually present and you can buy salts test kits online as well. Do a google. Otherwise find a building surveyor with appropriate experience and the necessary equipment. Specifically ask if they can sample and analyse mortar to accurately identify moisture content and also do salts analysis.

You may find there is not as much dampness in the wall as you think. I have seen the sort of damage you have internally many times on exactly the same construction walls that were well exposed and well ventilated externally.

If you do find dampness the analysis should isolate where it is coming from and you can target the solution instead of randomly trying things.

I think there is a good chance you will find dampness in the upper wall due to that wall coating. If it were mine I would get that off anyway. A pressure washer might remove it.

Also check your internal environment. A simple way to do this is purchase some condensation test strips and stick them to your walls in various places. l'll bet now that you will find you are suffering from some condensation at least.

I also think it's inevitable that you will find penetrating dampness at low level. If it were mine I would remove 250-300mm of driveway to a depth below your internal floor level and install a drain in it's place.

Beware of blokes with electric moisture meters. Sticking pins into masonry walls like this tells you nothing useful - they are only calibrated for wood. Non invasive capacitance meters can help to guide but needs to be interpreted. You can't just say; it's off the scale - inject, inject, inject.

I'd also bet that the driveway has not always been at that level. Why not speak to some older neighbours or try to find some old photographs that might help pinpoint when the level was raised.

 

[yamato]

thanks a million jeds, prince of darkness. I'll look into some of these.

as for the drive height. I have some old pictures. It used to be a council park and the council sold it to the developer. The old pics show it WAS amazingly at that height. The only change has been, further down the wall, he's added a flower bed. That definitely wasn't there before. He's also added block paving and an aco drain which runs right up against my wall.

I tried repeatedly to contact the council about whether or not this had been approved and they just basically told me to eff off.