Rising Damp? Help!

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Hi,

I'm new to this forum, and I hope that I am posting in the right place. Please could you guys offer your advice on my damp problem.

I am in the process of buying a house that was constructed circa 1910. We expected our survey to report that some damp had been found but not in the place we expected. Our survey reported that on the front of the house on the RHS a combination of a leaking gutter and blocked gully has caused the RHS bottom corner to have perished brickwork, covered in moss and look damp. Although it looks bad on the outside, inside there is minimal damp and we suspect that if the guttering, gully drain and brickwork are fixed it should (after a while) dry out.

Of more concern is about 2 meters away from this surveyor spotted damp corner of the house, middle of the front facing, about half a meter from the door is another isolated patch of damp that has penetrated inside and has rotted one of the floor joists and is leaving permanent wet patches to the lower wall. The vendor is rectifying the floor joist as part of our contract, but where could this source of damp be coming from (no leaks in the middle of the gutter and no obvious other source)? Its a long way for that little bit of gully water from the corner to travel?

The house is fitted with a blue brick dpc but inspection of the mortar between the blue bricks reveals some of them have mortar missing, does this mean that the dpc is broken? (Searches on the internet have initially indicated that these dpc very rarely fail) Can I buy some blue bricks (of the same size) and replace them if they are? Or would another solution give better results? I should mention that the front dpc is only slightly above the pavement, I guess the pavement (council owned) has got higher over time and there isn't much I can do about that...

Any help would be much appreciated .

Thank you :)
 
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Your topic title is not what I think you have, I would suggest it is more likely penetrating damp albeit at low level.

It really needs photo's to help comment on that type of problem. But still no substitute for actually seeing it. When the vendor replaces the joist make sure the end of the joist has been wrapped with a Damp Proof Membrane to form a pocket for the Joist end.

When you get a wet spot as described, there is often a particular reason, this could be a leaking drain, water pipe or whatever. You may need to investigate further which may be difficult if the house fronts onto a public footpath.

As for Blue bricks, you can still get pretty much any size you want. A fair few old imperial sizes are still made for the old house market, others can be obtained from reclaimation yards. It is even possible to have bricks custom made. You would not need to replace any blue bricks if they are a typical engineering stock, so you should only need some if you are adding some in elsewhere. I cannot recall ever seeing any old perished engineering blue bricks, only damaged ones! The missing mortar needs pointing up (after cleaning out the joint). Out of interest what is the size of the mortar bed joints?
 
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You will probably find the cavity is full of debris and is providing a direct transfer of free waters from outer to inner leafs or through candle wick effect to debris within cavity. Install suitable double air bricks to provide ventilation within cavity and during installation clear cavities of all debris as far as possible. Make sure you have adequate ventilation to sub floor spaces which will involve knocking through inner brick leaf to provide this. Re-point existing brickwork.
 
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You will probably find the cavity is full of debris and is providing a direct transfer of free waters from outer to inner leafs or through candle wick effect to debris within cavity.

You reckon it will have one then ? I would not expect to see many in 1910

Unless existing sub-floor ventilation is a problem, putting further air bricks in is unnecessary! - I think it has probably been generally fine for the last 100 years

There is nearly always going to be some "crap" in between bricks whether a designed cavity or not. Stopping the source of dampness and local pointing up may be all that is required. Clearing out cavities is something to consider IF it has one.
 
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Basing my opinion on the area I live in so could be wrong with cavity assumption, properties here 1900 plus, 95% have cavities and 100 years plus of debris is becoming a problem especially if cavity insulation has been injected.
 
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Why hasn't the surveyor answered these questions via his report?
 
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(Searches on the internet have initially indicated that these dpc very rarely fail)

Where have you been searching?

These can fail when there is prolonged saturation and aged mortar, and certain ground salts. So not rarely, more like commonly
 
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Thanks for all your replies.

Firstly, I have included some photos, I have annotated some of them to try (hopefully!) to make it clearer what the problem is.

The first photo: shows the house from the front view. Externally the damp is visible in the RHS corner, underneath the small window, underneath the door and spreading to underneath the LHS window. Internal damp is highlighted by the red squares - in the RHS corner, the rotten floor joist and under the LHS window.

The second photo: shows what the surveyor has attributed ALL the damp across the front of the house to - the blocked gully and drain on the RHS of the house. But how could the water travel all the way across the front of the house? I have tried a little experiment to simulate a heavy downpour - pouring 5 litres of water into the drain, it did not overflow, but it did not drain away either. I really don't see how this can be the cause of all the damp.

The other photos show how the damp is seeming to travel across the front of the house.

Any thoughts on where the damp might be coming from would be very welcome? and any possible suggestions to at least stop it in it's tracks before it gets worse inside? I don't hope for a complete cure as it is a old house!

Blagard - Thanks for your advice, I will make sure the new joist is wrapped up!

dave1953 - The house does definetly not have any cavity walls.

^woody^ - I have been reading about chemical injection DPC, a lot of websites suggest that the brick DPC very rarely fails, but I am thinking it is real possibility for this house. From the photos, do you think this could be possible?

Thanks for your help :) View media item 56658 View media item 56658
 
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Very clearly a traditional solid 9" wall with english bond on the section where between door and main window.

The gully could well have been cleared, none the less those gratings frequently get blocked by leaves, plastic bags etc. So any water not going down the drain is going to flow across the front of your house. Hopefully there is not a cross fall on the pavement that pushs surface water towards your house.. The open perps in the brickwork certainly will not help matters and conventional respointing is not going to work with those very narrow types of joint. I would be inclined to get a stiff wire such as a stainless steel wall tie and bend it to rake out any rubbish and follow up by pointing up using a injection technique with a cartridge gun.

I am not convinced it is damp under the windows. Certainly the brickwork looks different but that could be due to years and years of the way rainwater runs down the face of the building marking the brickwork differently.

With genuine soild 9" walls, the inside face of the wall will get cold and at low level there will be a risk of condensation - That could contribute to the apparent dampness. The two factors that help keep condensation at bay are heating and ventilation. You might want to consider dry lining the inside of the external wall using an insulation backed plasterboard. However I am mindful that you have not made any reference to dampness on the return end wall, it may be because it is well sheltered.

Initially I think your best bet is to keep the gully clear and to deal with the open "perps" (vertical joints between bricks), then see what if any improvement occurs.
 

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