Damp cellars and basements - how to dry them out

it's been a while since I've done a video and I thought coming up to Christmas in cold weather and sometimes damp weather it might be an idea to talk about selves because one of the things that we get lots and lots of inquiries about these people who say we've got a damp basement or a damp cellar and we don't know what to do with and one of the things that always comes up is that people are told that they have to tank the cellar in order to make it dry and live in it well not a good idea why is it not a good idea to take a cellar tanking is something you do to a structure to effectively waterproof it now if you think of a cellar as a hole in the ground it's a it's a trench or if you like a swimming pool now they make swimming pools out of cement and that's what tanking does he turns your cellar into a swimming pool now okay if you don't put water in the screen pool the theories at the cellar stage dry because it actually tact is turned into the giant tank is any more problem with that and that is that the structure of the cellar outside of the tanking in other words the walls of the cellar are then able to get very very wet so what you end up with is water all around the walls of your cellar and you've not yet thought about the floor you tanked the walls you might well have put something on the floor but of course what you're doing then is you are filling the sir building fabric around the the cellar that walls the floor everything with water and that then starts to deteriorate the building fabric so if you've got old Sam stone for instance or limestone and you chuck a load of water into that it will slowly start to dissolve the stone and the most easily dissolved part of it is the mortar and quite often we go down and do surveys in cellars and basements and we see that the the mortar joints and everything that glues everything together has been heavily eroded away by by water because people have been tanking the system okay so what else is going to happen well of course you're going to get water evaporating out of those walls and the water will gradually visit we're writing down clumsy because water will naturally evaporate and as the water becomes a gas it rises it's a very light gas and I'll do another little video while we've got the camera set up and I'll talk about the relationship between water as a gas and water as a liquid and dew points and all the rest of it but I think at the moment we're looking at the cellar and we're saying okay there's moisture in these walls and it's going to go upward so where does it end up it ends up in the walls above the cellar or above the basement and you can just an equally look at this as being the subfloor of a Victorian st. where you've got a timber floor and you've got a bit of an air space below that the timber floor and now the air space is supposedly being ventilated and of course if we block the vents by building the soil that you then get a very stuffy damp environment under the timber floor which is why your timber floor rots and I'm actually sitting in my my study of the modes of what I'm going to do is I'm going to pick camera operator we're going to take you around this and show you some of the things that happen if you get a wet so now that we have a web server we have a doubt seller and what we're going to do is have a look at how we make that sell a drive without thinking it and it all comes down to ventilation and when we do Building Surveyor I would say probably 95% almost a hundred percent of the sellers and the basements and the subfloor areas that we look at are badly ventilated now if you let those areas get a little bit damp and it's done because moisture is constantly working its way out is diffusing out of the walls its evaporating out of the walls of its present as a liquid if it's present as a gas but it's diffusing into the air in the cellar so now you've got some damp air in the cellar what are you going to do with it because if there's no ventilation it can't get away and therefore moisture builds up the total moisture content of the air in the cellar goes up the relative humidity goes up and you end up with anything that's timber down there for a start will you forget wet and start rotting or it will get slightly wet and if it's above about 12 percent moisture content then get our little beetle start chomping at it and you start getting wood work so what is the solution well actually it's ridiculously simple you ventilate it but just banging a hole in the wall of your sight he's not going to do anything because if you bang a hole in the wall you'll get a bit of air coming in through the hole but you don't then circulate air through the cellar so in order for a cellar to work or a basement to work effectively until you warm and dry what you have to do is you to move the volume are there in that space out of the space and if you look at building brakes it says they have which house would have something like two and a half air changes an hour well how many sellers and basements have two and a half air changes a day or a week they don't so they get wet and then you come to us with problems so a simple solution is to ventilate it and ventilating it even if you have a hole wherever there and a hole over there you can't guarantee that you're going to get an air follow what you're then dependent on is this wind blowing from this side and blowing the air through out the other side in which case yes you would have a nice dry cellar but how often does it happen it doesn't so what we have to do is we have to establish a non-official system where we draw the air from the cellar and then we shoved out through wall and we say okay we're gonna bring in some warm dry air we're going to push the wet air out through the wall and seller and replace it with warm dry here now there are two ways of doing that if you've got a nice warm dry house like this one and we're going to show you here are we going to show you a very wet cellar underneath this is in the original sandstone but it's actually sitting on top of clay and the seller sometimes actually had running water running through it but the important thing here is at my floor and the beams in the thought are bone dry and that the the walls of our cellar are actually starting to dry out very selling silly thing happened years ago in that the cellar was painted with cellophane which is impermeable so that walls actually find it quite hard to dry out but we're working on that and I'll show you so what do we do we we suck the air out and we replace it with in the building and for that to happen you've got to have vents or openings around the floors so that the nice warm dry air in the house can circulate in and work its way through yourself if conversely you want to work the other way around you can actually have a ventilation system that will look for the driest source of air and it will bring dry air into the cellar and if it's coming from outside and weather is very cold it will warm that air up so that the air coming into the cellar this isn't about 15 degrees centigrade and then the the moist damp air is pushed out through the other side and so you have an active system that is able to pick air up push it through the cellar expel or damp air on the other side and that can work backwards and forwards depending on whether you're taking air from a house or the outside where bottom line is that you have to have a ventilation system so it understands the air quality and when I talk about air quality I'm talking about the total amount of moisture but he's dissolved into the air and that is measured in grams per cubic meter and dry air is about seven grams which is about a teaspoon full of water in a cubic meter wet air starts to get very wet around about 12 grams and if you've got more than 12 grams it's pretty damp wet horrible air and at 12 grams on a high humidity you'll be rotting in timber so you need to be very careful you've got to keep control over the amount of water dissolved in the air now where most Federation systems go wrong is that they only measure the relative humidity and relative humidity is most pretty useless measurement because the relative humidity can change from zero to a hundred percent at a given Jojo and the amount of moisture dissolved in the air doesn't actually change if you keep the relative humidity at say 75 80 % anew and you maintain the total moisture content the temperature can change it's a bit like a seesaw and I actually described the whole relationship between these three variables as a seesaw and we take that total moisture content being a pivot of a seesaw and if you take a plank of wood and stick it on the pivot this is temperature this is drugs of humility so for a given amount of moisture in the air if you take the relative humidity to a hundred percent the temperature drops and where it's a hundred percent is in a special case that 100 percent reading there that temperature is known as the coupon and at the dew point water will condense if you move it away from the dew point the relative humidity drops and you're back to a situation where you won't get condensation forming within the walls so what you have to realize is that measuring relative humidity is actually not a very clever thing because you can have a relative humidity of a hundred percent 7 grams 8 9 10 11 12 13 20 grams it doesn't matter you still say relative humidity but the amount of moisture dissolved in the air can go up and down so what we do is we measure the total moisture content and that is what we do with thermo hydrolysis which is these things that leads in our surveys they cost about a thousand pounds so you guys probably wouldn't buy more you can buy them on Amazon better cheap things about 25 quid and they'll give you quite a good reading the one thing they won't do is the absolute the total amount of water dissolved in the air you have to do that with software I'm in here at the moment in my office it's 18 point 8 degrees centigrade it's thirty eight point seven percent relative so very very dry in terms of the relative and the total moisture content is six point three grams per cubic meter so it's actually very dry air it's almost too dry so we're not going to get any damp in this room absolute beginner so I'll only confuse you too much but what I'm trying to get across the people here at the moment and you're gonna have to watch another couple of videos to understand this relationship between temperature and relative humidity the bottom line is if you goddammit seller or damp basement or a doubt subfloor to your house don't panic because ninety nine times out of a hundred what you need is better ventilation you do not need expensive tanking you can spend three or four hundred quid and get good humidity controlled ventilation units that will over a period of time draw moisture from the cellar and make it perfectly livable and we're going to go down in the cellar here now and we're going to show you a little bit about how we've done it it's very simple not complicated and we've got about three or four hundred quids worth of equipment in the cellar and I will show you and before we go into the cellar I'm just going to turn the camera onto the floor and we're going to show you the the nail holes and this is one of the the things that you will see if you're looking at the cellar they need these are the the boards in my my study and you can see that there is a bit of staining and dis staining is because the seller has at times been quite damp so nails are rusting so these are the class a symptom of a cellar that has too much water in it and you can very often find this if we're doing a building survey you will actually find this in people's front rooms so you can have a little Victorian semi and if you've got timber floors if you have a look at the floors if you can see slightly rusty nail heads like this then you know that there's too much moisture underneath your floorboards and that will tell you that somebody had probably blocked up the ventilation through the cellar or through the the subfloor and you need to get better ventilation now in your Victorian semi part of the reason for that is that very often in the old days the floor was able to vent from front to back of the building then people filled in in the room at the back which was usually the kitchen so he took the floor out and you filled it and then he put a cooker in there what you've done is he blocked off the vent halfway through the house and the house can no longer vent so the the back the middle wall in the house usually gets quite wet or under the stairs because there's no through flow ventilation and it's that through flow ventilation of air that is super critical for keeping those those subfloor areas dry so whichever way you go if you've got a big space like we've got under here you need full control of the ventilation if you've got a very small space and just a narrow hole a couple of ventilation bricks are good but you've got to make sure that air is actually through flow of air so it's super critical it's that one thing that we see in any every survey not enough ventilation I'm going to keep how powering the ventilation because it's the one thing that causes dampness in buildings but this bit we're going to show you now we've got weakening units I'll take you in the cellar and you can have a look at the the gadget tree that's in the cellar which is a simple and hopefully you can then take steps to make your own cellar dry without having to spend a lot of money with damp Wally's tanking the face okay so let's go look at the cellar

Channel: Peter Ward

Views: 85,781

Keywords: PCA, damp house, basement tanking, basement waterproofing, damp wally, property care association, old house, damp walls, rising damp

Id: RbyaRgkfhwg

Length: 17min 16sec (1036 seconds)

Published: Mon Jan 13 2020