Rising damp advice please

[Freespirit44]

Apologies for posting here. I need to make a decision pretty soon so I'm here for traffic and advice!
We live in a 1950s semi and have damp patches in several places. Two patches on the wall of the covered up chimney,(downstairs living room) this backs onto our neighbours kitchen wall.
two in separate areas of the kitchen. (One on the wall backing a downstairs WC, the other on the wall backing our garden)

We had a damp proofing company round today and they quoted just under £9k to get it sorted. This would include injections, protective membranes to make it more solid, vents in almost every room.
He said that it's rising damp due to an old damp course eroding and that due to houses moving etc over the years, water is seeping through. He said it's definitely not a water leak.

Any advice around wether or not I should go for it would be greatly appreciated.
@pigletjohn if you are around, I would love to hear your thoughts.

Also, I would welcome any suggestions about having vents in every room. This is a new concept for Me and I'm out of my comfort zone with all this!

Thank you.

@Freespirit44 Periodproperty.co.uk is a good forum. Post on there, they have a depth of info regarding issues such as you have.

Well done for not going ahead with the other company - good call.

Yes as a pp has said, vents can help but can also cause as many problems. It is a fine balancing act to allow the house to breathe but not to get too many flunctuations in temp. Heating in older houses is best left on for longer periods of time at a lower temp.

@schloss thanks, I will have a look. The heritage website has loads of info too. What a perlava!

I think you have received the main points.

Damp is usually caused by building defects, such as leaks around chimneys and windows, or pipes or drains. Sometimes it is caused by soil or paving levels being raised against the wall and bridging the dpc.

Or by insufficient ventilation, such as blocked fireplaces or airbricks, or inadequate steam extraction in bathrooms

Or by excessive moisture load, such as damp washing draped indoors or steamy showers without adequate exraction.

Interestingly, not one of those sources of water will be repaired by injecting silicone into walls or painting damp proofing chemicals onto them.

Most houses in Britain less than two hundred years old were built with a damp course, most often slate. Slate lasts hundreds of millions of years and does not wear out.

Anybody who tells you your damp course has "failed" or that silicone injections will cure your damp should be asked to leave.

@PigletJohn thank you so much for replying. Much appreciated. From the pictures I have posted, do you have any inkling as to where the problem is coming from? I have a chimney man coming round next week take a look at the living room damp stains.

As for the kitchen, I used to dry my washing next to the radiator in the utility area which I have stopped now. If I can't find the cause then will it be worth still using extractor fans, windows, dehumidifiers etc? We have young children so I'm concerned about damp causing health issues for them.
In your experience, would vents in every room be a good idea?
Thank you.

@PigletJohn it might be worth mentioning that the man who came round said that the slates may have broken as houses move occasionally. We do have some cracks. His theory is that slates have broken hence the damp.

It's worth bearing in mind that older houses don't have damp proof courses at all and still don't have damp.

How much was he expecting your house to move to break slates 🤔

@AnnaMagnani that's interesting 🤔 that's the thing, because I have no idea about these type of things, I have to believe what the builders say

Yes we have to take notice of professionals but it sadly has to be with a pinch of salt a lot of the time. Take time to gain knowledge on the various forums there are, even go to a library and look at period property renovation books (there are lots!) so that you can smell bull when builders/tradesman talk to you.

Once they realise you have some knowledge it actually becomes easier talking to them.

I had a funny situation with a builder who was the sort who probably would have preferred my husband to talk to him, we were discussing lime plaster, he was very full of himself and asked "do I know what lime plaster is and when it is used". We were standing by a recently lime plastered wall - builder said, this is lime plaster waiting for its topcoat, you can see the hair which has been mixed in with the plaster. I know I replied, I mixed the plaster and plastered the wall!

@schloss fancy that! A woman knowing what lime plaster is 🙄

In London, DPC became mandatory in 1875.

Most other town and cities followed soon afterwards.

Some better builds had them before then.

Clean unplastered brickwork does not absorb water very high because each course of mortar acts as a partial barrier, due to the change in pore size. Capillarity will pull water from large pores to small, but not from small pores to large.