Roger440

A narrow trench each side with coarse clean stone, and ensure the surface is cambered when its redone. If its flat, it will never last.

I didnt have it done. Both my houses had had it done previously. Both were damp well above floor level. Ive also seen a fair few others. My current house is the best. Holes drilled in what i believe is whinstone. Completely impervious to water, but the chemical will somehow infiltrate the wall, (nearly 2 ft thick) and create a moisture impermeable layer. Sure.

Butyl tape. Apply this where you intend to "puncture" the VCL. Problem fixed. Certainly standard procedure when putting a VCL on wall. Just done it my workshop.

Im afraid you will not convince me that its anything other than a good wheeze to make cash. Appreciate you may think/believe otherwise. Ive seen enough of it to know it doesnt work.

My point was, and is, the effects of artifically raising prices will be socially and politically unacceptable for the reasons i already stated. Anyone suggesting that as a route forward should maybe consider their moral compass? I would be 80 by then, so resonable chance i wont make it anyway. Maybe you read a different article to me? Either way, its not a future im looking forward too.

Inclined to agree. Ive had 2 houses that have had chemical injections. Completely (ineffecive) joke. If its below ground level and a road is the other side though, thats going to be a problem. Whatever you do in that circustance, the wall will remain damp. Its just how you live with it, disguise it etc.

Why is that? Removing the tank that is.

Lets hope im dead by then...................

Nobodys going to do that for the very obvious reasons that have been discussed before. A goodly chunk of the population cannot afford to "change" away from gas no matter how expensive gas is. So they will simply be very cold or hungry. Or both. Easy to say if you are not one of the affected. Though in the crazy messed up world we live in, i guess, eventually government will pay you to do it. Which i think is the approach i will take. Just wait until they pay for it all. Its the inevitable conclusion of the path we are currently taking. Mind you that might be unachievable as the grant harvesting companies will keep putting up their costs inline with the grant increases.......................

Possibly slightly on a tangent, but when i had the dubiuos priviege of looking after a fleet of trains, we always had lots of complaints about cold carriges in winter, and to a lesser degree too hot in summer. Investigation usually revealed all was working as intended. ie, the system was controlling the internal temp to 21c as expected. However, humans being fickle, this wasnt the answer. So we ran an test one year, to increase the target temp to 23 for winter, and 19 for summer. Being rekleativelt simple, this involved a manual adjustment twice a year. The results were better than expected. complaints dropped to a fraction of the previous levels. Illogical? Maybe. But its the reality. Having stood on a freezing cold platform for 15mins, you wanted it warm when you boarded. 21c didnt fulfil that criteria. I confess, it applies very much to me in that circumstance. Like wise in summer when its 27c outside. Getting on, 19c is great. Im the same at home. Despite the fact the living room is at 21, im layered up. In the summer, it would be just a t shirt. At the same temp. Maybe im odd.

You said its not damp now, but didnt say, what, if any covering is on it now. If what you want to fit is no less permeable than whats on it now, then id suggest the risks are low. On the other hand if its a bare wall, or just lime plaster, then risks are much higher. As i already suggested, no one will give you a definitve answer. It will come down to judgement and your appetite for risk. With absolute respect to those on this forum, there are other places with much more practical experience of older buildings than is available here, this being pretty focussed on new build. Warning though, some can be hardcore limeists! Believing its the answer to everything, or just open the windows to ventilate!!! PS. As im sure you have read what i did to dry my last house out, however my neighbours took their traditional modern builders approach and put a DPC a meter up the wall and boarded over it. Looks nice, and is is damp free. However, im pretty confident, indeed, can see, that the walls are damp. And im sure, just like mine used to be, if i drilled into them, slurry paste would come out, not dust. Sadly, this is the industry standard for damp walls.

Ive just done the walls of my workshop, which are concrete block inner / 75mm cavity / concrete block outer. 100mm of pir with battens. Foil faced both sides and taped. However the software still siggested a degree on moisture build up in the walls. Adding a decent vapour barrier fixed that. So thats what i did. Does it work, yes, very much so. Will it never get the dew point in the wall? Dont know. No way of knowing, but i put very much worst case numbers in to the software. Would i do this on a a wall with no DPC? Definetely not.

I thought so too. Initally, the thread wasnt making sense. Mine is on the inner. So im unclear why or if i would need the shocks to close off the cavity?

If you are 100% confident you have fixed the sorce, im not sure id be too worried. It will dry out eventually.

Based on logic, yes. But no such thing seems to exsist. If it does on paper, either no one has found it, made it, or it doesnt work in practice. For me, at least, it working in practice is rather important.

That is the generally considered view. However, the usual warning is not to make it too good, as you will drop the wall temp, which "may" lead to a dew point in the exsisting wall. You dont want that. As always, this will vary wildly from house to house. And the key point is, ALL the long term risk is yours. No one will guarantee a solution that wont see the return of damp at some point. Despite the chat in this thread, no one is going to test your house and make/draw up a plan. The last point being a major consideration for me at least, when deciding what to do with my money.

I have, but it seems to be looking at a different problem, ie moisture buffering for indoor comfort/humidity etc. Im sure thats all very interesting to some, but is not the same as what im talking about, which nothing to do with "moisture buffering". But what im calling moisture "shedding". Sure, theres common factors, but its not the same thing as far as i can see. I agree the term breathable is largely pointless But really, it not that relevant is it. Yes, of course, some buildings without DPC will be fine. And? Some are not. No one is going to conduct extensive investigations into an old wall(s) to determine exactly how wet it might be at any given point in time. At different times it will be different. The fundamental problem, is there is no DPC. I note you didnt offer a practical solution to that issue. So, faced with a house that has "some" damp in the walls, you need to decide what to do. I could read some reports, like those posted, but does that help me decide what to do? No. I know, however, that if i do it in lime, it has the best chance possible of not having a problem going forward (assuming of course ive done all the obvious things to reduce moisture getting into the wall, im taken that as a given). Were i to do it in something less "breathable" then i increase the risk of a problem. I say again, i might be fine. I may be able to put foil faced PIR in front of it, and a vapour barrier over, effectively reducing moisture movement to zero. And still be fine. But it might not. So back in the real world, one has a choice to make. Unless someone else is offering to pay for rectification if there is a problem, then, when spending your own money, go with the lowest risk option. Maybe you would do different, but i cant afford doing it twice. There is no practical testing available to homeowners to allow such decisions to be made, even if one wanted too. So the default option is lime, because its the most likely to work given a damp wall. I emphasise likely. Just to add of course, is that with a moderately damp wall, it can take years, maybe decades to manifest itself, visually. So walls you "think" are ok, maybe anything but.

Im no scientist, but it remains, that stick gypsum over a damp wall, it will resist, for a while. Eventually, salts will appear on the surface, and if bad enough, the plaster will become detached from the wall. By which time the damp will be the best part of a meter up the wall. This is VERY common to see in older, non DPC houses. Stick lime plaster over the same wall, and nothing much happens to it. Yes, moisture will enter the room, but the wall will be unaffected. And it will be drier IN the wall.

I cant argue with the logic. But as i said earlier, on a house without a DPC and likely less than optimal construction, how? Aside from demolition. Theres a few million homeowers would love to know............................... In the meantime, until you come up with a PRACTICAL solution, ill work on the basis of shedding that moisture.

Yes, it will. Problem is, it always cracks, as it not very flexible and houses move. It slightly change a well known phrase, theres only 2 types of cement, cement thats cracked, and cement thats going to crack. As pointed out earlier, you can often see the damplines on rendered houses after heavy wind blown rain.

Lets be realistic, how are you going to retrofit a DPC to a house? (please dont say a chemical DPC, thats utter bollocks and nothing but a scam)Especially one of stone and rubble infill construction? Please, come back to the real world. Having the wall allowing water to evaporate faster than it gets in is how old houses with no DPC work. Sadly, of course, it didnt always work. There were no calculations to do that way back when. It was hit and miss. The really bad stuff has invariably long since gone. Short of demolition, you have to accept and work WITH it if you want a damp free house. When i did my last house, i admit i was sceptical too. But removing the inappropiate material completely fixed things. When i started the walls were so wet, the socket back boxes had corroded away (in 10 years) and if you drilled a hole in the wall it came out as a slurry. Stripped the plaster off, repointed the outside in lime to replace the cement, removed the concrete slab on mud. In a matter of weeks, it was completely dry, to the point drilling a hole in the wall at ground level produced dry brick dust. Frankly, it was quite amazing to watch over the weeks. At the new place, which is stone with much thicker walls, we uncovered the fireplace early on. It had been pointed in cement. The bottom 2 feet some of the stones were dark and wet to touch. Chipping out the motar revealed the lime behind that in places was so wet, you could push your finger into it. Its taken 6 months this time (and the outside is still painted and pointed in cement) its dried out. The motar is hard, well as hard as lime ever is, stones have all dried out. Ive only repointed a small section so far. Again, practical real world experience. Which for me wins over hypothesis.

Pretty much everything is breathable to some extent. Gypsum plaster is breathable. Just not as much as lime. If the moisture absorption into the wall from the ground exceeds the abilty of the wall to shed it, then you have a problem. Gypsum is less breathable than lime. Thats just a fact. Will it be a problem? Depends on the moisture. And that can vary hugely depending on build, materials, place etc. If you have no DPC, then lime plaster gives you the most likely good result. Will fitting gypsum give a problem in any specific setting? Who knows. At a practical level i had an issue with damp pushing the gypsum plaster off. There were other factors i dealt with to reduce likely damp in wall. But at the point of plastering i can either do lime, or gypsum. Its highly likely Lime will give me no further trouble, a higer risk of a negative outcome with gypsum. Others are free to make their own choice, but ill stick with the lime in such circumstances. As an aside, and as a result of practical experience, the ability of gypsum to breate appears to dimish very significantly when its "polished". Which, of course, it always is. I wonder if the "tests" take that into account? As you though, even if gypsum was breathable enough in a particular application, thats rather worthless if you stick a less breathable paint over it. And most modern paints are pretty impervious.

They do. Assuming not buggered up with cement. But if you move the dew point into the wall, then the wall, or just the motar if a hard stone, is going to be damp for at least a good part of the time. And a damp/wet wall is a thermal disaster. Aside from any longer term implications to the integrity. I need to repoint the outside and inside of my place. Problem is, im not skilful!!! I want to insulate too, but getting a clear answer on how much you can apply before you start creating problems in the wall itself is as clear as mud. The reality is, you wont know until after you have done it.

Theres heaps of evidence! Look up the values. Plus plenty of practical real world experience. Cornwall is overflowing with buggered up stone houses. The old stone building in Porth Leven harbour being a classic example. Cement motar perfect, stone face heavily eroded. Had the issue on my own house. Removing cement fixed it. Just repeated it again at the new place which is stone built. Cement is, for practical purposes, waterproof.

What Ian R said would be my primary concern. Insulating will reduce the temp of the wall. And increase the condensation risk in the wall. Problem is, so many variables and unknowns in an old wall like that. Including how damp, or otherwise it is.