Damp problem

[Davethedrum]

Hello,
I have recently bought a terraced house in the North West and am having trouble figuring out what to do about its damp problem. After reading about rising damp and how it is commonly misdiagnosed I am not sure of the right the way forward and would gratefully receive any input. I would rather find a ventilation solution or install a physical DPC rather than use a chemical DPC which I see as a last resort. I was wondering if @pigletjohn would be able to help me?
The floor level is about the same as the ground outside (both at front and back) and the pointing on the front is cement-based. There is a cracked drain at the rear. It has been unoccupied for about 9 months to a year and doesn't have a water meter. I can't tell if it has a DPC but today managed to take some photos of what could be the original one. Any comment on whether this is a DPC would be very welcome. I will find a way to attach some photos.
Thank you for any help you can give. I will be ready to answer any questions.

Here is a link to some photos www.engineeringadmissionsassessment.com/photos.html

how old is the house

where are the damp patches

have you got a water meter

you have long term wet near the gullies, and the paving looks cracked and sunken, so no doubt they are broken and leaking. I think the paving is above the level of the DPC. Walk up and down your road to try and find a house where the ground level has not been raised. Count the number of brick courses below the doorstep and compare to your own.

When you start lifting the slabs round your gullies you will probably be able to see the dpc (you may have to hose mud off the wall). I expect you will also find a cavity, and some red worms, and that the mortar between the bricks has washed away between the bricks.

The broken gullies wash away the soil. This causes the gullies to subside into the cavity, and also the slabs. I think I can see both has happened.

it has probably happened under the soil pipe too. look out for wild tomato plants as well as the red worms. Both thrive in damp soil rich in decaying organic matter.

Trying to repair from above by cementing the gullies is futile.

p.s.

in one of your pics you can see riven slate under the joist where the cable goes through a gap. If original, the slate will have been provided to protect the joist from damp in the bricks. Slate lasts at least 250 million years and does not wear out.

I see you have additional airbricks added, so the damp has been going on for a long time. Some of them look blocked and painted. Clear them out so air can flow.

pps

is the hall floor concrete?

ppps

in the photo with the car, the stonework on your house looks wetter than the stonework next door. This may be due to rusted or blocked gutters spilling over in rain.

Replacement with new plastic gutters will be one of the easier jobs, and will probably reduce the amount of water on the front paving. With luck you will be able to find the same brand as your neighbours so they will join without needing an adaptor.

Do not allow anyone who sells silicone injections anywhere near your house.

I’m not pigletjohn, but i deal with damp in historic buildings as part of my job, so I might be able to help…

Historic England have some great webinars explaining damp in old houses - search “Historic England technical tuesdays”

Rising damp is almost never the problem. Water flows downhill, not uphill, and damp low down in walls is often because the fabric of the wall is effectively filling up with water above the DPC. Caused by water getting in at a higher level and tricking down until it’s stopped by the DPC.

Start at the top: are the gutters and down pipes sound? Is the roof sound? Check on a rainy day. Downpipes often fail at the back, where they touch the wall.

Then, look at the walls: is the pointing sound? Are there cracks or failed areas? The cement pointing will be stopping water vapour escaping, but it won’t stop water getting in especially from wind-driven rain. Might this be the problem?

Inside: what plaster is on the walls? If the house was built before about 1930 it would probably have been built with lime plaster and mortar, which allows water vapour to evaporate through it. If this has been hacked off and replaced with gypsum plaster, it may be trapping water that has got in from the outside (see above) - at some point the dampness in the walls becomes too much for the gypsum plaster to keep back any more , and the plaster starts to fail.

Hope this helps you explore the problem!

Hello @PigletJohn and @dontbenastyhaveapasty,
Thank you very much for your insights - it is much appreciated. In answer to your questions:

The house is circa 1900
The damp is in the dining room and under the stairs and a little bit at the front. These are probably the original plaster but the back of the dining room and other (dry) walls have probably been redone in cement render.
There is no water meter.
The hall floor is concrete.
The gutters and roof are ok but we don't have a downpipe - it relies on next door's so it's probably worth having one and replacing the gutters.
Do you think there is a DPC? Does that felt look promising?
Thank you again - I am most grateful.

"The damp is in the dining room and under the stairs and a little bit at the front. "

external walls or internal walls?

Are any of these walls adjacent to the concrete hall floor?

If you look for the external water stopcock in the pavement, and the internal one under the position of the original kitchen sink, do you think the pipe passes under the hall floor?

"The gutters and roof are ok "

so why is your front wall wet with rain, but not the neighbour's?

Hello again,
Thank you @PigletJohn for your help. I will have a look for the stopcock later and report back tomorrow. None of the walls mentioned are next to the hall floor and all the damp I can see is internal. About the wet wall, the rain was driving from the left of the picture and the downspout and windows have shielded the other house a bit. Their exposed bit of wall was wet as well but probably not as much as mine so I will ask my roofer to look at this (they are already prepared to ensure weathertightness of the roof etc.) when they do their work.
Thanks again.

'mmm, if the damp is on internal walls (I mean, walls that are not "outdoors" on the other side) then it is not what I expected. I thought that the external walls, close to the raised paving and the leaking drains, would be the wet ones. Have I understood correctly?

Hello again @PigletJohn. Thank you for your help. I think I misunderstood internal/external before - sorry about that. The wettest walls are actually internal ones and there is a slightly damp wall which is external. Here is a link to the plan of the house www.engineeringadmissionsassessment.com/plan.html. The worst walls are marked in orange and the slightly damp one in green. The ground level slopes very gently from the front to the back of the house.
Thank you again.

can you add the chimneybreasts and fireplaces, please?

and the sink or othery watery things.

If you look undedr the floor, does the ground slope downwards towards the back?

does the ground under the floors seem wet (I presume it is not concrete?) and are there any slugs, mud or worms?

I'm considering the idea that water might be penetrating at the front, and running down under the floor until it meets a solid wall, such as the stair wall, and the dining/kitchen wall.

If you can scrape a bit of a trench, running side to side of the house, in the earth under the floor, you can look to see if it collects water, after heavy rain. A garden trowel would be enough, I don't suppose you can get a spade under there.

It might be an idea for you to mark on a plan where the central heating pipes run, then the hot water and cold water pipes.

I’ve seen a couple of houses with this sort of pattern where the problem was a tiny bit long-term leak from a central heating pipe (the ones that run from radiator to radiator). They are often concealed under flooorboards so a leak can go undetected until it has saturated its surroundings.

It might of course be a water pipe leak in your neighbour’s house, the other side of the party wall…

Hello @PigletJohn,
Thank you for your posts. I have updated the plan to include chimney breasts and the kitchen sink here www.engineeringadmissionsassessment.com/plan.html. Yes, the ground under the house does slope gently from front to back but I would say only by a few inches. The ground is just earth, not concrete but doesn't seem that wet and there is no mud/sitting water or slugs/worms. I will dig the trench as suggested and look up and down the road and for the stopcock and report back tomorrow.
Thank you again.

Hello @dontbenastyhaveapasty, thank you for your posts. I will have a look and add these to the plan tomorrow and speak to the neighbour if they are around. Thank you again - it is much appreciated.

Hello @PigletJohn and @dontbenastyhaveapasty. I have had a chance to have a look at the things you have mentioned:

The hall floor is in fact wood - apologies for this mistake before (I wasn't home at the time and was relying on my memory and knowledge of a similar house nearby).

The stopcock is in the back alley so I think the supply goes from there to the sink (through the yard).

I scraped a trench near the back of the dining room. It was fairly dry.

I walked up the road and all the houses were like mine except the last one which shows the DPC a whole brick below the level of my outer ground (this is a major positive step - thank you for suggesting it).

I have updated the plan to include pipes, the supply and two more slightly damp walls (the back of the living room and the very narrow part between the living room and the stairs). The new plan and photos can be found here www.engineeringadmissionsassessment.com/new.html. I have included some more photos of the walls because I am not very good at identifying plaster. The newly plastered wall is the back of the dining room and is probably sand and cement. The 'red' (left of dining room) and 'green' (under stairs) looking walls are old, possibly original and I can't tell what type of plaster it is sorry. The dry and slightly damp walls are painted and look newly plastered (again, probably sand and cement).

Another observation is that the gulley at the front doesn't seem to do anything - it is level across all the houses and water just seems to sit in it.

Thank you again for your help. I had a quote for injecting/replastering for over £9000 so I am glad I did some more research.

Thanks for the updated plan. My money’s on a leaking pipe or perhaps 2 leaking pipes, going from that drawing! Water ingress from outdoors would be likely to have a very different pattern overall.

You might find that damage from water leaks is covered by your house insurance.

A water pipe is often at fault, but it is usually the old water supply pipe buried in the ground. In your case the supply pipe enters at the back of the house and goes to the kitchen. It will then go by some route upstairs to the bathroom and/or loft (if you have a cold water tank up there)

the other pipes you draw appear to be a pair of pipes fpr the radiators, and are visible under the floor, so a significant leak would be visible.

Does your boiler have a pressure gauge on it?

Have you got a water tank (or two) in your loft, and are they full?

To check for a leak in your water supply pipe, as you have not got a water meter, you can use an engineers stethoscope. Press this to the indoor stopcock or incoming pipe under the sink while as assistant turns the outdoor stopcock off and on. The leak makes a faint hiss you may hardly hear, but late at night, you will notice it stop and start when the outdoor stopcock is turned off and on.

As we can see your gullies are leaking, it's my opinion that the water is due to that, and the bridged DPC, at the front of the house. The back is less clear, unless you can look under the kitchen floor (or is it concrete?) The supply pipe may be leaking under the kitchen.

Reject all offers of silicone injections and concealment plaster.

p.s.

lime plaster is usually creamy-white and smooth. Sand and cement is used in damp areas, often to cover up damp, grey, and may seem smooth, but if you scratch it, the dust will be gritty.

modern gypsum plaster is usually pale pink or light grey, will look chocolate if wet. When wet, it has a recognisable smell.

p.s.

as the gas and water pipes seem to go to the chimneybreast, I guess you have an old backboiler, perhaps a Baxi Bermuda. Might be 50 years old. Are the pipes copper?

there is likely to be a small water tank in the loft, about the size of an old WC cistern. Observe the ball valve. When you press the ball down, water should flow in. When you release it, it should stop. Does it?

Hello @PigletJohn,
Thank you for your posts. The engineers stethoscope is arriving tomorrow so I will be able to report back about that then. In the meantime:

I have attached a photo of the boiler here www.engineeringadmissionsassessment.com/boiler.html. It is a Ravenheat CSI 85AAA (T) 780 series, probably about 16 years old. There don't appear to be any water tanks in the loft. There is one small tank like you described but it is disconnected (I included a photo of it anyway). There is a pressure gauge and I will monitor if it drops and report back tomorrow on that as well.

The kitchen floor is concrete. As for identifying plaster, I think the left dining room, under the stairs and the back living room walls are sand and cement. I am still having difficulty with the newly plastered wet back dining room wall. The third photo is after a bit of scratching - it seems as though it could be gypsum or entirely skim but I'm not sure - apologies for this.

I guess that the question about plaster is not what is there but whether to replace it and what with. The surveyor suggested www.safeguardeurope.com/products/dryzone-system/dryzone-renovation-plasters which seem ok but I would be grateful if you had any comment on this.

Thank you again - this has been most helpful.