Check for Condensation before renting

HappyMJ

Leo2020 wrote: »

Our last home had no problems with condensation and mould. However, come rain or shine, summer or winter the bedroom window and bathroom window was nearly always open - only slightly mind - they could still be locked.

We rented it out and the first tenants decided to run a tumble dryer inside with no outside vent - the result was damp patches and mould on windows/ceilings.

The house has wall and loft insulation. A relatively new central heating and double glazed PVC windows/doors. Plus an extractor in the kitchen.

The mould was not our fault but the tenants.

Running a tumble dryer indoors (with no venting outside) or drying clothes on rails indoors (with the windows closed) will have exactly the same effect. When the washing cycle is complete there water in the washing that needs to be removed. The only real difference is the dryer rapidly removes the water.

seven-day-weekend

Can someone explain to me how the air circulation system mentioned is better than a dehumidifier (if it is). I need to be able to explain this to my husband.

Innys1

seven-day-weekend wrote: »

Can someone explain to me how the air circulation system mentioned is better than a dehumidifier (if it is). I need to be able to explain this to my husband.

A dehumidifier extracts moisture from the ambient air and pumps out the dried air.

An air recirculation system has not been mentioned. A positive air system has, which I suspect is what you are referring to.

A positive air system is, essentially, a low pressure fan which pumps fresh air into a property. It does nothing specific in relation to moisture extraction, though has the side effect in forcing some moist air out when fresh air is pumped in.

As for which is better, they are both options for reducing condensation - neither is better as they both do different things. In a small house, a single dehumidifer is probably enough. In a larger house, more than one dehumidifier is best, possibly used with a positive air system.

princeofpounds

I really dislike the old canard that condensation is entirely a lifestyle issue.


It can be. But as a couple of the more sensible posters in this thread have pointed out, poor building construction and design (and this country is terrible for it when it comes to condensation issues) are, in many cases, the dominant factor.


By all means, occupiers should reasonably be doing the basics like not drying clothes on radiators and opening windows when showering, when safe to do so.


But in my mind, it ceases to become a lifestyle factor when the lifestyle required is unreasonable to maintain.


For example, leaving windows open all day whilst absent from the property. Not having a daily shower. Not being able to boil a pan. Not having outside space to dry clothes.


I have even lived in a house that turned out to have a problem in an extension that only contained a bedroom. The only 'lifestyle' occurring there was breathing.


There are three factors in causing condensation - moisture production, cold surfaces and lack of ventilation. Occupiers only control the first one and part of the last one, and only then up to a point.


I have seen so much housing with terrible, terrible design that almost guarantees problems from relatively moderate lifestyles. Bricked-up chimneys and air vents. Inadequate heating systems. Bathrooms with a small window or none at all, and no proper extraction systems. Single glazing in the wrong places. Flats with nowhere to dry clothes or install a tumble-dryer. Modern flats with vast amounts of insulation and airtight construction but with no ventilation system. Kitchens with no ventilation. HMOs with cold cellars converted into rooms to squeeze out an extra quid. Single skin bricks walls. Cavity walls with failed/bridged cavity wall insulation. The list goes on, and on, and on.


Some housing stock in this country is terrible, and we do ourselves a disservice by insisting that occupiers should always bend their activities to the will of the property, rather than the property serving the occupiers. You wouldn't accept it from any other consumer good.


It might be practical that people have to adjust as it's not a problem that can be solved over the short term. But because it is expedient does not make it right.

dragonsoup

I'm currently battling condensation problems in my recent purchase. I've never had any problems before. The house is 1850 or thereabouts, solid stone with intact and good condition rendering and a tight slate roof.

Unfortunately the previous owner has installed wood burner stoves and double glazing with no trickle vents. It was never designed to be sealed like this and the air bricks are not enough. I'm now considering scrapping at least one of the wood burners and reinstalling an open fire in the chimney instead.

As for lifestyle factors -the tumble dryer is not in the house, the kitchen has an extractor hood ( used!), both bathrooms have extractor fans and I leave the windows open - not sure whether that helps given that it's been raining solidly for weeks now and there is more moisture outside than there is inside...

I suspect the solution may have to be insulated plasterboard on the worst affected wall.

HappyMJ

dragonsoup wrote: »

I'm currently battling condensation problems in my recent purchase. I've never had any problems before. The house is 1850 or thereabouts, solid stone with intact and good condition rendering and a tight slate roof.

Unfortunately the previous owner has installed wood burner stoves and double glazing with no trickle vents. It was never designed to be sealed like this and the air bricks are not enough. I'm now considering scrapping at least one of the wood burners and reinstalling an open fire in the chimney instead.

As for lifestyle factors -the tumble dryer is not in the house, the kitchen has an extractor hood ( used!), both bathrooms have extractor fans and I leave the windows open - not sure whether that helps given that it's been raining solidly for weeks now and there is more moisture outside than there is inside...

I suspect the solution may have to be insulated plasterboard on the worst affected wall.

Can you open a window and lock them slightly open which would have the same effect as trickle vents?

When the wood burner is alight it will draw fresh air from the slightly open window and into the room and pull it into the fire and up the chimney. Opening the window slightly will refresh the air from outside rather than from another room.

There is moisture outside. The dew point (100% humidity) is about 7 degrees C. Increase the temperature of the air and the Relative Humidity (RH) figure falls as warmer air can carry more moisture. Get the room to 21 degrees and you should at least get the RH down to 60%.

Cold spots in houses will have condensation issues which is why the advice is to move furniture away from outside walls so that air can flow around it preventing a cold spot behind the furniture hopefully preventing the wall getting condensation on it.

Innys1

dragonsoup wrote: »

I'm currently battling condensation problems in my recent purchase. I've never had any problems before. The house is 1850 or thereabouts, solid stone with intact and good condition rendering and a tight slate roof.

Unfortunately the previous owner has installed wood burner stoves and double glazing with no trickle vents. It was never designed to be sealed like this and the air bricks are not enough. I'm now considering scrapping at least one of the wood burners and reinstalling an open fire in the chimney instead.

As for lifestyle factors -the tumble dryer is not in the house, the kitchen has an extractor hood ( used!), both bathrooms have extractor fans and I leave the windows open - not sure whether that helps given that it's been raining solidly for weeks now and there is more moisture outside than there is inside...

I suspect the solution may have to be insulated plasterboard on the worst affected wall.

Oh dear.

Solid stone walls with, presumably, no cavity wall. That means the walls will invariably be freezing cold and water in the air will condense on them. Not a good start.

princeofpounds

I'm now considering scrapping at least one of the wood burners and reinstalling an open fire in the chimney instead.

Doubt that's the best solution. If your aim is to increase passive ventilation you might be better off just installing more vents and not losing the stove (which is much better for heating than an open fire).


Or you might want to look into active management, like a positive pressure system.


What the best solution is really depends on whether there is too much moisture trapped in the house (and so the dew point is unreasonably high), or whether the level of moisture is fairly normal but the stone wall at that point is just too plain cold (meaning condensation would be produced at almost any liveable interior temperature/humidity).


Because of what you say about the wall being stone, I suspect it might be the latter rather than the former.

dragonsoup

HappyMJ wrote: »

Can you open a window and lock them slightly open which would have the same effect as trickle vents?

I do this already with the sash windows at the front of the house, unfortunately the worst affected rooms don't have the sort of windows that allow this.

HappyMJ wrote: »

When the wood burner is alight it will draw fresh air from the slightly open window and into the room and pull it into the fire and up the chimney. Opening the window slightly will refresh the air from outside rather than from another room.

That means using them - I know I know. I'm the only one in the world who dislikes wood burners! Getting dry wood for them is a real problem up here. With an excellent oil fired boiler they are more of a nuisance than an asset which is why I'd be happy to lose them.

HappyMJ wrote: »

There is moisture outside. The dew point (100% humidity) is about 7 degrees C. Increase the temperature of the air and the Relative Humidity (RH) figure falls as warmer air can carry more moisture. Get the room to 21 degrees and you should at least get the RH down to 60%.

Cold spots in houses will have condensation issues which is why the advice is to move furniture away from outside walls so that air can flow around it preventing a cold spot behind the furniture hopefully preventing the wall getting condensation on it.

I heat to 22C from 5pm to 10pm each day and from 6am to 8am. I can't justify leaving the heating on all day whilst the house is empty and as for cold spots - it's a detached house high on a mountain near Snowdonia and we take the brunt of the weather on one side. That's the side I'm thinking of the insulated plasterboard for.

Roll on spring!

andre_xs

Just one further suggestion how to tackle condensation:

To minimize increased heating costs, it is usually advised to rather briefly (e.g. 5-15 min) open *all* windows (and potentially also doors) *as wide/much as possible*. This will allow a nearly complete exchange of all air in the house, but without the walls, furniture etc to cool down. The new fresh air gets warm very quickly. Do this 1-4 times a day, depending on your needs.

In colder countries, e.g. Austria, Switzerland, Southern Germany, where temperatures can easily be as low as -10 to -15 degree during the day for an extended period, this is the only viable solution...