Whole house struggling with condensation, despite being cold and drafty...

Interested in any strategies that anyone has implemented for ridding or reducing condensation from a house like ours. Looking around I can see lots of advice relating to new builds or that suggest creating ventilation - but our house is:

Old and made of stone without foundations, sitting in wet valley
Surrounded by trees and hedges no doubt keeping in humidity - but also doing a good job I hope of eating up ground moisture
Drafty - all single glazed glass across the house, poor seals on doors and windows and in various spots, you can feel the draft around timbers and beams. More ventilation would help I suppose, but already very cold and breezy.
Cold - stone interior with lime based plaster if not bare stone.
Tall and skinny - we have 3 floors, but they are perpendicular to the main house (its a big 'L' shape with the main living space running horizontal and the bedrooms as you go up. Therefore, hard to find a spot in the house that would have line of sight to all windows.

Every single room has condensation every single morning that the temp outside dips beneath around 10c (we're in the UK). Its at least a 25-30 minute job to hoover up all the moisture in the AM, often necessary to do at least once more in the day too, but regardless the next day windows are covered in moisture. All the windows are wood and now at a stage of rotting / having mould on them - enormously expensive to replace but I'll have no choice for some in 2020. Black mould spots in my young children's rooms is of particular concern for their health.

We're already trying to keep doors closed in bathrooms and alike, lids on boiling pots, no clothes drying in the house and still its just sopping wet this time of year.

Is there a solution that I've missed? All I can really find is putting huge energy sucking, expensive dehumidifiers in every room - which is going to cost a fortune to implement and run, let alone be noisy. That doesn't feel very permie friendly, nor really addressing the issue, just the symptom. That might be all thats open to me, but before I break the news to my wife that we're having to spend £££'s we don't have, interested to hear any other solutions to these sorts of issues.

Greatly appreciated...

Hi MJ;
Wow, the only thing I can think of are rocket mass heaters.
Several small ones. Brick bell batch box's.  In bed rooms and  a bigger one down stairs.

I realize that is probably not an option for you. But if you can....
Of course things like, caulking (if possible) where there are drafts.   If replacing the windows is not an option, then cover them with plastic. Hang wool blankets over doors to stop drafts. Like they did in castles, hang tapestries over blank stone walls.

At times I have fantasied about living in a stone castle... or cottage.   Then I think about how cold stones are and how long it takes to warm them up...
Then being as I am a rocket scientist , I think how warm King Arthur would have been with a nice rocket mass heater...
Of course I also think that about Geronimo and his tepee and how warm he could have been if only ...

Well MJ , I hope I didn't come off sounding like a foolish American,  I mean, I guess I am one but... at least I'm not a politician. :)

It's those very cold glass surfaces that condense all of the moisture in your inside air.  You need a second layer at the windows that will at least create a dead space.  

I was fortunate that most of my 100 year old windows had storm windows on the outsides, but the curtains still billowed with cold air infiltration around the frames.

Replacing the worst of the rotted windows one at a time, sealing the spaces around all the windows with either spray foam insulation or batt insulation and insulating all wall and ceiling surfaces has been a continuing process over decades.

There are organizations in our US communities that can help with these projects if you meet their income guidelines.  Perhaps they also exist in your neck of the woods?

Just as a cheap experiment, buy a sheet or two of rigid plastic and fasten them to either the sash itself or the window as a whole.  See whether that helps much with the condensation.

What heating do you have? Wood stove? Central Heating? Radiators in every room?
If it's really drafty, you can't heat the place up properly. Humid air comes in all the time. If you can't heat up properly, you can't evaporate all the water from the walls and condensation into the air. Which is what you want to do and then open the windows and get all that high humidity air out when it's low humidity outside (sunny cold day , unfortunately unlikely in UK). But there must be days where there is less humidity in the air.
Which is totally contradictory to what people think, You open the window, a lot of hot air leaves the building, cool air comes in. But they say that it takes less energy to heat that air, because you don't have to heat all that water which is in the air after.
Or was it mornings you have to vent? I've heard that early mornings the outside air contains usually less humidity. It cools in the night, cool air can contain less humidity so then it falls out everywhere. There was a rule like that. But that you can find out.
Insulating the attic and in between floors (blow this papery insulation in)might make it easier to get the place heated up properly.
When i renovated my place i had done a lot of concrete and rendering of walls which caused humidity, This helped then.
Also there where no gutters at the time, so water just ran onto the wall. Drainage pipes dug under the flooring, concreting it up with a plastic vapor barrier underneath. I am running a pipe from the gutter from the front of the house under the floor to the lower back end of the house into a reservoir. All things that helped. No condensation here. Got one wood stove, that's it.. There is some draft, which i likeold barn redone, but nothing exaggerated.
But i can see you can't do these things short term. Maybe you could get everybody to come to one floor or two floors? Make it more compact for this winter. And then the heat bill won't be so high.
Next summer might be another scorcher, open windows all the time and vent,vent,vent.

Do you live on a hill? Could be that you could divert the flow of water with drainage pipes and store it in a pond or something away from the house.

People throw out crazy good windows and windowsills, double glazing even, check your local window builder/ installer. He/she will know, if you come with maximum measurements ( can always fill a bit up) he/she might have them soon. Here they're happy if you pick them up for a bottle of something. Drill a few holes put in plugs et voila.People make their own improvised greenhouses with them.

Ruth and Hugo have good suggestions.

I live in a very drafty tiny house that gets humid very quickly, just because of the size. Because it's so small it's easy to heat, so we just get the place up to 30°+ and then open windows to vent the humid air. Like Hugo said, if you can't get your place warm, you can't move much moisture.

I like storm windows on the outside. Then the coldest surface is the storm window, not your actual window. So if condensation wrecks a window it's going to be the cheap one, not your nice inside one. Glass is nicest to look through, but it's heavy and not good when it breaks. Plastic will work fine, but it's not nice to look through and, well, it's plastic.

All of our windows were free from a contractor. My husband was at a job site and asked the window guy if he had any jobs lined up where we could come take the old ones. He said he had a whole house set of casements he'd just removed sitting at his place and gave us his address. Two days later, we had more windows than we could use.

Ah that sounds like a familiar problem, now my old house also sat in a bog, it had brick walls but again no damp course and plenty of drafts! Now we didn't get condensation on the windows as we had double glazing and never heated the house past around 15 (9 was not unheard of in the kitchen in the morning) But we did get mould everywhere, and damp sheets and a total inability to dry any clothing is seriously unpleasant/bad for ones health. fixing the condensation can be done very simply, it forms because of the difference in temperature between the warm inside and the cold walls/windows, so simply stop heating it and the condensation will go away... however that really isn't a very good solution!

So what we did was get a dehumidifier. it would pull 3-5 liters out of each area of the house daily, we would run it in one room/group of rooms for a couple of days and then move it round, obviously buying two would have been more efficient but.. money. Yes it adds to the electric bill, but really not that much, and they are not noisy, just a hum from the fan. it also adds heat which is a very nice side effect, I would advise that you do not get a refrigeration style unit but get a silica gel condenser. the former doesn't work well at under 18C and stops at 10C whereas the latter goes right down to 0C without much loss of efficiency. Since our house was never at 18C... it was a no brainer which to get. This one is what we have it was not that expensive 4 years ago so it's quite probable you can find one cheaper somewhere.


Things that will keep it warmer but not necessarily remove any damp would be curtains or plastic covers on the windows, also good old fashioned draft excludes.

This is all great stuff, thanks.

Yes, I should have mentioned - double glazing would help alot, as maybe would storm shutters or similar - but the house is also listed Grade II. Its another well intentioned system of governance that in practical application is a nightmare to navigate. Basically buildings of cultural or historical interest are 'listed' with a grading and then to make ANY changes externally (often internally too) you must seek permission from the local council. This means engaging with the local conservation officer who, may be reasonable ('replacing the windows like for like is fine, but with the addition of double glazing) or not ('these must remain single paned windows, regardless of what that means for the occupants health, wallet or wellbeing'). Its a lottery and totally down to individual conservation officer whim but either way its damned hard to sort. Standard conservationist mind set to be honest. Luckily its just the outside of the building thats listed.

Hugo Morvan wrote:What heating do you have? Wood stove? Central Heating? Radiators in every room?
If it's really drafty, you can't heat the place up properly. Humid air comes in all the time. If you can't heat up properly, you can't evaporate all the water from the walls and condensation into the air. Which is what you want to do and then open the windows and get all that high humidity air out when it's low humidity outside (sunny cold day , unfortunately unlikely in UK). But there must be days where there is less humidity in the air.
Which is totally contradictory to what people think, You open the window, a lot of hot air leaves the building, cool air comes in. But they say that it takes less energy to heat that air, because you don't have to heat all that water which is in the air after.
Or was it mornings you have to vent? I've heard that early mornings the outside air contains usually less humidity. It cools in the night, cool air can contain less humidity so then it falls out everywhere. There was a rule like that. But that you can find out.
Insulating the attic and in between floors (blow this papery insulation in)might make it easier to get the place heated up properly.
When i renovated my place i had done a lot of concrete and rendering of walls which caused humidity, This helped then.
Also there where no gutters at the time, so water just ran onto the wall. Drainage pipes dug under the flooring, concreting it up with a plastic vapor barrier underneath. I am running a pipe from the gutter from the front of the house under the floor to the lower back end of the house into a reservoir. All things that helped. No condensation here. Got one wood stove, that's it.. There is some draft, which i likeold barn redone, but nothing exaggerated.
But i can see you can't do these things short term. Maybe you could get everybody to come to one floor or two floors? Make it more compact for this winter. And then the heat bill won't be so high.
Next summer might be another scorcher, open windows all the time and vent,vent,vent.

Do you live on a hill? Could be that you could divert the flow of water with drainage pipes and store it in a pond or something away from the house.

People throw out crazy good windows and windowsills, double glazing even, check your local window builder/ installer. He/she will know, if you come with maximum measurements ( can always fill a bit up) he/she might have them soon. Here they're happy if you pick them up for a bottle of something. Drill a few holes put in plugs et voila.People make their own improvised greenhouses with them.

Heating is oil fired radiators (which I'm desperate to do away with) and 2x woodburners. The oil fired at least distributes heat to each room, whereas the burners just operate locally in the dining room and lounge (and to be honest, make little difference to the condensation). I need to deal with it every morning and even now (just after 7pm local) most windows are starting to bead up.

If you use electricity to create hot water, you may consider replacing your hot water heater with a combined heat pump/dehumidifier ...these units will passively remove moisture from the air as they create hot water (the condensation is a by-product of the heat pump).
They won't function as well as a dedicated dehumidifier, but should help to alleviate your moisture problem to some extent. Note that these units only produce condensate as they create hot water ...so if you use only a little hot water, they may not be very cost effective.

Of course I would recommend doing some research before going this route, as you will need to provide an outlet for the unit to drain. Here's a couple links to get you started:

https://www.greenbuildingadvisor.com/question/using-a-heat-pump-water-heater-for-basement-dehumidification-has-anyone-done-this

https://www.geappliances.com/ge/heat-pump-hot-water-heater/water-heater-faq.htm

Ventilating the house will only be useful to reduce humidity if the air outside is dryer than the air inside. If that's not the case, you will want to seal up the house as much as possible.
Also make sure there are no leaks in the roof, plumbing or around the foundation that may be contributing to the problem. Make sure downspouts drain away from the foundation.

The storm windows I'm familiar with are removable. It's just a framed piece of glass or a frame with plastic stretched over. You fit this over the outside of the window in cold weather and take it down in warm weather. There are various ways to keep it in place. My parents had little swivelling wooden tabs attached to the outside of the window frames. I'm sure you could come up with something nonpermanent, too. Would even something temporary that doesn't change the existing structure not be allowed?

Edit:
Even when it's been raining for days outside, the cold wet air outside is dryer than the air inside our house. Sometimes in the spring or fall when it's been really wet for a long time we'll light the stove and vent, just to dry out the house a bit. Humans and their activities give off a lot of moisture.

This makes it even more complex with those regulations. Weird you can't change your glazing for double glazing. Who would notice from a distance? Ridiculous rules in this day and age that you can't have double glazing reducing CO2 output. Houses flooding regularly because of climate change and bad management of waterways, but bureaucrazy is keeping the houses perfectly how they were a century ago.

Don't let it make your blood boil! That might cause more humidity.
Good other people have some great suggestions because i ran out of steam.
Oh no, maybe one. Keep the windows that don't show any sign of rot well painted. Especially these bottom bits where the water accumulates and likes to sit. You can't use water based paint on oil based paint, it will fall off. The other way around is no problem i believe.. You can take all the old paint off using chemicals and sanding, and prime it with waterbased primer but that's not really an environmental win either. Sigh.

My guess is cold humid air leaks into the house.  You heat it up a bit and maybe the dew point rises a bit.  The windows get a bit colder at night and the surface of the glass drops below the new dew point and you get condensation.

Unless you can keep the fresh supply of humid air from leaking in, I think you may have to approach it by keeping the inside surface of the glass warmer.  I found a fix that works for me (in this thread) and Graham Chiu implemented a more robust solution in his architecturally limited neighborhood.  His video is about halfway down that thread.

Another thought is to try to heat the house up more so that the glass is kept a bit warmer.  Maybe crank the heat up a bit for a couple days and see what happens...

Not often considered but a material contributor to moisture in a house is moisture migrating from the basement, crawlspace or that region between the earth and the first level of flooring.  If that space is accessible, obtain plastic sheeting and lay it on the earth covering the entire crawl space.  Overlap the sheeting by 4' to 5' at joints and then at the perimeter allow the sheeting to turn up and lay against the foundation for 5-6 inches.

Then, again, assuming you can access the lowest level in the house, look for every place that a pipe, duct or other mechanical facility penetrates the floor.  Once identified, seal the area around each pipe, etc, with fire retardant expanding foam or other fire retardant material to stop and/inhibit the movement of cold, moist air from the crawl space or basement from moving through the floor to the living spaces.  You should also, assuming it's accessible, go into the top most space in the house and look for any vents, pipes or other mechanical facility penetrates through the floor, including the area around any chimney.  Again, seal these  using code approved foams, sealants and if necessary, metal flashing, to stop/greatly reduce any air flow from the lower floor(s).

The goal in these efforts is to reduce the "chimney effect" in your old house created when air, heated in your living spaces expands, rises flows out of the house and moisture laden air from the crawl space (and outside) flows in to replace it.

With respect to your windows, until you're ready to replace them, remove any old caulking from around them, then re-seal using code approved materials.

If you walls are 100% stone and/or masonry, that's a project for another day...

Best of success with this project.

You can put in interior double glazing on a grade II you might also find that you can have standard double glazing on the back of the house even though they won't let you have it on the front. I know all about the fun of listed buildings, the one I have experience of was started in 1400 something, and edited up until the 1940's but now you MUST NOT CHANGE ANYTHING including the colour outside which must be pink.. because that happened to be the colour it was when it was listed.  Unfortunately the inside is also listed to a point, so only real horse hair plaster is allowed, that is not easy to source I have to say.
What I did was do a full set of drawings of the existing house and the new double glazing and how it would look. since the double glazing essentially looks exactly the same we were permitted to put it on the back of the house, but the front no. even though we wanted to replace single sashes with double sashes that was a no no. so instead we went for interior glazing it's permanent and you lose your window ledges, but other than having to open two windows every time you want some fresh air it's a lot better than freezing.

One thought, if someone has been modern and torn all the carpets out, put them back, it's amazing what a difference that extra insulation on the floor makes.

Temporary thin plastic film over the windows will help a lot with both condensation and overall warmth. Also, if your windows are anything like ours, you probably have airgaps and drafts coming in around them. We have a season autumn job of going around and wedging kitchen paper towel in all the window gaps. Takes an hour or so to do them all, but make a HUGE difference to the overall temperature/airflow.

You should also look at the obvious things to reduce the moisture that gets into the building in the first place - dry your clothes outside, make sure your bathroom has a good extractor fan, and use the fan in your kitchen when you have a long steamy cooking session happening.

One other silly detail about sources of moisture in the air...  We'd sop up the condensation with a towel and then hang it inside to dry.  Took us a winter to figure out that we were just putting the water back into the air to condense on the windows again.

As daunting as all what needs doing to your home might seem, it will eventually all get done, and it all adds value to your home/property.  It helps avoid expensive repairs later.   Mold growth is very often a cause of a vague kind of illness, so it's important to keep everyone healthy. Sorry this is so long, but I kept thinking of stuff.

I've been through this with different types of buildings, and it's always amounted to don't let in any moist air from outside.  Once you have it sealed, if you want airflow you can always open windows for cross-ventilation under controlled circumstances.  Drafts are 24/7, so imagine how much moisture is coming in, especially overnight?  What's going on outside is coming inside.

- A really good ladder

Invest in at least a 9 foot/3 meter tall, really safe and stable ladder for maintenance inside and out.  Even if a 6 footer/2 meter would do it, the stability is worth it.  Store it in a dry place so parts of it won't rust.


- Sealing Doors, Windows, Plumbing openings:

It's crucial to seal all doors and windows, plumbing where it enters through the walls or floors with a stretchable silicone-type caulk that is paintable.  One brand I know of in the US is called Big Stretch.  This stuff has lasted for years and years, no redoing like other caulks I've used.  There is probably something similar available in other countries.  It has some colors like white and grey and tan, but it's paintable so it doesn't matter, other than the white is handy because it stands out while working, and you know you've gotten the spots filled in without any tiny holes.  

Check to see how long it needs to cure before rain.   The stretchable part is important because other types of caulk tend to shrink after they dry, or are clear and won't cover with paint, but don't have the stretchability that is important for a building that expands and contracts, even if it's just on wet soil in the winter and dry soil in the summer, even trucks or a train going by and making the ground tremble can affect a building.  All buildings move a little bit over the years.  I did run across one seemingly good caulk, but it said, "For outside use only," so check labels.

Always trust mice and rats to find the little openings where drafts are.  If you find droppings look around for openings and seal those with the stretchy caulk.  If there are exterior trims on the corner of buildings or sheds, reach up under that trim and feel for an opening.  Rodents love to chew their way in through these corners.  I fill those with the black elastomeric roof tar that is in most hardware stores.  They can't chew through this.


-- Windows

About the wooden windows, if there is just mold, just wetness and no rotting, brush on a solution of 50/50 bleach and water.  let dry and reapply if necessary.   Once the wood dries there is an additive to paint that stops mold and the frames/sills can be painted.  It's usually how the windows were installed that creates problems.

If the windows have outside trim on them, if possible, take the trim off and make sure they were installed with caulking all the way around the frame, not just inset then covered with trim.  They are easy to caulk once the trim is removed.  Not all trim will cooperate, but is easily replaced.

Someone installed a window for me once and they forgot to take the drain plugs out of the lower part of the frame, and the inside sill was wet all the time.  Seemed so obvious that should have been done, it took me a while to figure it out.

- Humidity meters

Having a few inexpensive thermometers with humidity meters in them helps to keep an eye on how things are changing or just how bad it is.  I've gotten mine at the hardware store for under $10.

- Mortar Checked

Have you had the mortar between the stones checked?  Do those need filling or repairing?  Mortar is not expensive, and is easy to apply when things are dry, but be careful not to breathe the powder while mixing it.   Use a special mask when mixing. It's got bad stuff for the lungs when dry.

- Dry Heat and Fireplace improvement

There are cast iron fireplace inserts or woodstoves that produce more heat with less wood.  They are expensive, but sometimes used ones are available.  Using single-wall indoor pipe allows the heat into the room from the pipe as well as from the stove.  They need a special piece that goes through the wall, and need to be a certain height above the roof, but if you have stone walls there may be ways around that.  

Always have them checked for cracks or leaks, and have carbon monoxide alarms in any room that has a fireplace or a wood stove.  Some woodstoves have pipes along the backside for heating water as well, so they are helpful in lowering water heating bills.

Kitchens have their own heat most of the time and don't need extra heat, but often have a lot of pipes that create drafty holes that need sealing.

- Flooring

You didn't mention what type of floors you have, but if they have any kind of fake wood paneling/planking, they are not helping absorb moisture and could be holding moisture underneath.  Those tend to be acrylic/wood blends or some kind of synthetic material.  Check for moisture and mold trapped under that kind of floor.  Often those are installed with a plastic layer of silencing material underneath them, which wouldn't help in a damp situation.

We've recently gotten mats for the doorways that are for wet and muddy pets.  They absorb a lot of water brought in on shoes and boots, shake out easily, and can go through the washer.

- Water Drainage

Is there a source of water flowing under the building?  Even if it's just draining in one part of the year?  If you see a heavy rainfall creating runoff around the foundation, trench it away from the building.  Reroute it with ditches to watch it for a couple seasons.  As it's possible to do, either line those ditches with chunks of rock in a stream-like way, or put PVC pipes underground coming from a French drain "upstream."

- Basement

Is there a basement?  Is there excess moisture there, like signs of seeping in the walls?  Mineral deposits on the walls that show signs of seeping water?  There are paints/sealers for stone walls on basements that will help keep moisture out.  The paint or sealer could be used on other interior walls as long as the label says it's okay to use in an occupied room.  There are clear versions that should maintain the look of stone.  Check to see if those should only be applied in the summer when things are dry.

Venting the basement is important to do, so vents should be all the way around so there's plenty of airflow.  Then seal thoroughly any doorway into the house from the basement, all pipe entries, all heating vents.

- Insulation

The driest house I've ever had, had the ceiling of the basement/underneath the floor of the first floor of the house insulated with really thick insulation, R19-R21 with a thick black plastic liner holding it in place and insulation under the roof.

- Sneaky Leaky Roof

Once I had a roof that was leaking just underneath the shingles and on top of the wood, didn't show from inside, and that room was always more damp than the others, sometimes 100% humidity.  I wouldn't have known the roof had any issues, except for how damp it was in there. Took me a while to find out where it was leaking.  There are tar-type roof repair products that can be used during the rain in a pinch.  

- Windows

About the double-pane windows, thermal shades and thermal curtains (both if you can afford them) help keep the cold out.  If there is the potential for passive solar heating on one side of the building where the sun tracks all day, and the side where the sun sets, those single-pane windows will let in the most heat, even if it's overcast late spring through early fall. There is a point where if the outside temp is too cold those windows will let in too much cold, then the thermal curtains help a lot.  Even getting a few months of solar warmth helps in the long run.

We have double pane windows and there's still condensation on them when the temps outside are cold enough and the temps inside are warm. A squeegee onto a rag makes it go faster.  There are beads that absorb moisture at the craft store that can be dried in a low-temp oven and reused.  Fill a thin fabric bag made of an old thin cotton sheet the width of the window and place these on the sills or hang one in each window.  These are not the squishy beads that are used in floral arrangements. Try a few and see if they help, every situation is different.

- Trees

If you've got large trees that are creating a lot of shade and keeping your situation damp, you might want to consider trimming, lowering, or thinning them.  Trees are great, but shade contributes to mold growth, especially on the non-sunny side of the building where you don't need summer cooling from trees.

Have you figured out (measured, recorded) your humididties, temperatures and calculated your dew points? This would give you actual hard info on what happens where when - which probably would help deciding your options. An indoor/outdoor thermostat/humidistat is (hopefully) not that costly. A secondary unit that you can move about the house would also help a lot. Recording the daily cycle outside and inside in different rooms will provide a good picture of how bad your problems are and where. The dew point indicates the trigger point when humidity starts to form.

Now do the same recording thing for the surface temperature of your walls and windows. The windows may need a "contact" thermo sensor - I'm not sure an IR pistol thermometer will read glass. But it may; try different angles and distances. Or get some "dialectric grease" from a computer repair store and cut a small (4x4?) piece of aluminum flashing - needs to be perfectly flat. Grease the piece and apply it to the glass, use a putty knife to gently force it tight against the glass. _That_ should be measurable with an IR pistol.


You have just mapped the war zone and identified enemy positions. <g> Heat is your friend because hot air holds (and sucks up) moisture. But you say drafts make it hard to heat the air, so: Heating the indoor _surfaces_ with radiant heat will raise the surface temps and raise the surface dew point so that the surfaces don't condense. Direct line of sight to a fire is one way, a simple radiant heater is another.  See below. Positioning those radiant heaters with clear line-of-sight to heat the problem spots is key. Using them _might_ reduce your oil bill.

Possibly "protecting" cold surfaces can help. There was an actual reason for all those ceiling-floor tapestries in old stone castles.

Taping (good  masking tape works; bad masking tape works but probably leaves glue behind) film over the window area (as mentioned above) certainly seems a cheap/easy try. Tape also works quick/dirty to stop "leaks".

Curtains (heavy, long) over the windows _might_ help. Don't know, but seems easy to tack a heavy blanket or two backed by a tightly woven sheet over a couple windows and see what happens.

As mentioned above, the sheet of acrylic plastic siliconed to and covering the whole of the inside sash frame has worked for me. Read the rules for your "listed" area closely. There may well be the word "permanent" and/or "visible" or similar appearing in the definitions of prohibited "changes". Quite possibly, non-permanent, removeable "changes" won't trigger a problem. Especially if they're not shoved in the face of an authority figure.

Regarding old wood windows: Read up on "restoring old wood windows". Of particular interest to you may be epoxy injection, depending on what wood is left to work with. That _may_ be a viable option. Don't "brush off" the spongy stuff if you want to  consider this - that spongy stuff can take up epoxy and turn back into solid functional structure. The chemicals are mean, nasty and expensive, but might fit your needs well. Depends on what your feel about how the sausage is made, I guess - it's a messy complex undertaking. Contracting it is likely expensive but if you decide to try it yourself be _very_ responsible and cautious. Take out the sash and do the work outside in well ventilated areas. Wear good nitryl gloves - use the heaviest ones that will allow you to work accurately. They recently became available in 9mil (.009") here in the states, don't know what you have over there.

Put a venting hood over the stove. Fight your way through the listing restrictions to get the vent pipe outside. It will be between 6" and 10", probably 7 or 8. Buy an expensive one that will suck the cook right out of the kitchen and that you can't hear running. Anything else will probably disappoint, in my experience. If you install a good vent fan you will need to insist on a "make-up air" duct to bring in air from the outside. Yes, even in your drafty house. The best place for it to provide fresh air is at floor level under or behind the stove - assuming there is some clearance under and behind (or around) the stove. That will certainly make a difference.

Ditto the bathrooms, though you don't need make up air. Buy high end _quiet_ fans rated for 24/365. Tell the authorities the house is rotting away and you really hate to see that happen to a culture treasure and would like to do your duty as a proper citizen to conserve the nation's history...  

Look for grants, subsidies, kickbacks, etc associated with preserving your cultural treasure.


Cheers,
Rufus