Outside rendering over damp course

[chrisbpt]

Hi All,

I recently bought a new house (built around 1895) and unfortunetly the front room has quite a few damp problems. To cut a long story short the front wall of the house was being effected by rising/penitrating damp.

This seems to have been happening as the slate damp course had been rendered over. I have chipped away the render to just above the damp course and was wondering what my options are now...

Do I just neaten up the render above the slate and paint the bricks below the damp course with bitchumen....or do I use waterproofing brickwork sealer?

Also when I repair the render should I miz up a lime based render?

As you can see from the picture in the link below there is a concrete slab just in front of the wall so I am a little worried about rain bouncing up the wall in to the brickwork.

Sorry the picture is a little big I'm not great with computers so wasn't sure how to change the size.

 

[stuart45]

The DPC should be 150mm minimum above the ground level, or rain will bounce as you thought.

 

[dave1953]

From the state of the brickwork above the existing slate Dpc it may have been compromised over a period of years. Any salt staining on your interior walls which would suggest rising damp? You really could do with a damp survey[ normally free of charge] to determine exactly what is happening.To repair the rendering and seal it will be totallly pointless if the slate Dpc is cracked and compromised.

 

[chrisbpt]

Thanks for your quick reply guys. The house has been victim to a lot of DIY kind of jobs by the previous owner. The foundations of the house are very shallow 1 brick below the damp course level in some places (as shown in the pic). The walls themselves are solid brickwork and don't have a cavity. Due to the age of the house the foundations are very shallow which was the norm for the time (1 brick is pretty poor though I must admit). I'm not 100% sure but I think the concrete slap you see in the picture may be a kind of do it yourself underpinning.

Inside the property, the brickwork has been injected with a chemical DPC as I can see regular holes drilled in to the brickwork at about 15cm above the slate. This obviously hasn't sorted the problem out. I'm going to have the concrete slab inside the property removed and replaced with a new one anyway as I want to raise the floor level up. The new one will definatley have the dampproof membrane running up the inside walls as high as the slate DPC (the existing one doesn't go high enough.. muppets!).

I should also mention that the brickwork throughout the property (upstairs and down) is pretty similar to what is shown in the picture. It's all a bit crumberly and brittle looking.

From what I have read I honestly think that the damp problem on this front wall is caused by the render bridging the DPC. I also had problems with penitrating damp from the side wall of the same room. To fix this I reduced the ground level as much as I could (due to the foundations) and made a kind of french drain with gravel. After cleaning the brickwork up this seemed to solve the problem.

The DPC all around the property is very similar to the picture above as it has little breaks (no more than an inch or so) and steps up and down in places but there is no damp. The house is on a slope with is why I guess it steps up and down.

The damp on the wall in question is only minor and if the slab is a kind of underpinning I really don't want to mess around with it if I can help it. I would rather try to stop/reduce rain bounce damaging the brickwork (at least for the winter) and see if this stops the problem. If that doesn't work then I will deffinatley get some specialists in.

The dampproof injection inside the property looks like it has been done by a 6 piped machine due to the spacing of the holes. This makes me think thats a specialist company may have done the work. I may be wrong here though.

I've read so much about damp specailists coming in and automatically recommending a injected chemical DPC that I'm a bit sceptical.

Hope you know where I'm coming from, I want to sort the problem out and don't want to scrimp on cost but at the same time if I do get someone in I also don't want to get ripped off which is why I have looked in to it so much. I honestly feel that trying to reduce rain bounce and patching it up is worth a try.

With that in mind which would be better to do.. Should I repair the render above the DPC and just paint below it with the blackstuff or should I use waterproofing brickwork sealer?

I've also thought about running a layer of DPC up againsts the bottom of the wall and rendering over it (Ok that is a bit cowboy..but hey if it works why not).

Thanks again for replying and taking the time to read all this