Roger440

I face a similar issue with my 70's extension. On a slightly diffrent point, if you go with EWI, then surely the cavity will need to be aitight. And thats not going to help if there is any moisture in there. Unless the cavity is 100% fill?

How will you stop the new (lime?) render cracking and allowing water in? I see Carrington Lime are running practical courses on insulating traditional walls.

The OP says wall has no DPC. So the wall will be damp/wet to some extent. EPS will trap that in the wall. As well as the acrylic render. With a DPC, sure.

Im not sure i understand why you think there will be aitr movement behind the VCL? Only if you leave air paths open to it. Surely the answe is not to. As per ProDaves suggestion? Ive just done similar in my workshop. 100mm PIR between batens, VCL over. But i sealed everthing before i started, which was onto bare block.

I took that to be the council have tasked him with this. Though i agree, it doesnt actually say that. As per toughbuttercups comments, why are the council involved? One struggles to imagine a scenario where the council getting involved is likely to have any positive or useful effect? Unless they employ directly. However, assuming stats are right, id suggest its because there are much easier ways to earn money. No amount of money could entice me into the building game, even though my skills and the trade have a useful amount of overlap. I dont really use most of my skills now, because selling stuff is easier and earns me more. And i get to sit in a warm office, not outside in the wind and the rain.

Yes i used the double sided. I may be misunderstanding, but why not put VCL UNDER the battens? Or, actually, why are you using a VCL as you have put a DPC in already. Or are you worried about condensation forming within the floor build up? Seems unlikely and thus overkill?

Yep. But the rule is, never mention canal walls or buildings built in rivers and canals. Because then you start questioning things.

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.