Cavity wall airbrick condensation issues

[Michaelsf90]

In our front room we have large patio doors and windows but at one side is a cavity airbrick. So that side of wall is prone to condensation, mould, paint bubbling etc.

So we plugged the chimney as it was heat loss, sound, smell of burning from neighbours log burner forced in when we run the kitchen extractor fan. Since then the condensation has been worse as the chimney provided natural ventilation.

My question is can I block the vent. The house has cavity wall insulation. Some vents have been blocked up. Siliconed over the front due to cavity wall insulation I'm guessing.

There are vents about a metre up from ground level then one right up near roof level. The one I want to block is one of the only cavity vents not blocked up and the one directly above it at roof level is not blocked either. Due to the vent being open that wall is obviously the coldest part of the front room so instead of the windows getting condensation that wall takes the brunt of it. I know condensation is an issue. We do have a dehumidifier but don't run it 24/7. Do I unblock the chimney to allow that natural ventilation again and just put up with the negatives or can I block the vent up?

 

[cross thread]

Try temporary sealing to see if it helps
unused chimney is best left with a vent.

 

[JohnD]

Airbricks do not cause condensation. Please post photos of your damp patch. Please take a wide photo showing the entire wall.

Also the outside wall. Show the entire wall all the way up to the roof and gutter, and include all downpipes, drains, gullies and plumbing.

Is the top of the chimney blocked?

What do you think is the source of water vapour? Do you frequently boil kettles, or drape wet washing over radiators?

 

[Diver Fred]

This, condensation, is one of the problems with the shift away from open fires/Gas fires that exhaust via a chimney - loss of natural ventilation. Solutions, difficult but a 'Positive Ventilation system' really helps. Keeps a moving airflow through the house ideally from the coldest to the warmest areas.

 

[Michaelsf90]

It's not a damp patch as in penetrating damp. It's definitely condensation which is definitely caused by the drying of washing. We open windows during the day before heating comes on and run a dehumidifier. I personally think temporarily plugging the chimney is the biggest issue as we have plugged the only natural ventilation.

The bathroom and kitchen both have extract fans but I know you need a source of air to have good source of extraction so we open a window and run the fans.

The chimney was just plugged with a chimney sheep. Easy to pull out. Older houses are definitely not designed to have no chimneys. The house is 1930s. Trying to eliminate all sources of draft and heat loss is difficult but the more we eliminate the more condensation problems we have

 

[Harry Bloomfield]

It's definitely condensation which is definitely caused by the drying of washing.

Why are you drying washing in the interior of the house?

 

[JohnD]

It's definitely condensation which is definitely caused by the drying of washing.

If you insist on drying wet washing inside your house, hang it in the bathroom, with the extractor fan on and the door and window SHUT. This will at least prevent water vapour spreading through the house.

Water creates a huge volume of vapour as it evaporates so not much air will be sucked out of your house until drying is completed.
A typical gap under the bathroom door will allow enough air to enter at other times. Opening a window prevents the extractor fan from creating suction in the room.

 

[JohnD]

The chimney was just plugged with a chimney sheep. Easy to pull out. Older houses are definitely not designed to have no chimneys. The house is 1930s. Trying to eliminate all sources of draft and heat loss is difficult but the more we eliminate the more condensation problems we have

If you put a board across the fireplace, or brick it up with an airbrick-size gap near the bottom, convection airflow will go up the chimney, reducing the risk of neighbours fumes from a defective chimney entering your home.

But as you have identified that the condensation is caused by wet washing, you know what you have to do to remove the cause.

 

[Michaelsf90]

We use a dryer but for big bulky things like towels we stick them on the radiator and put on the dehumidifier. The smells from outside only occur when the kitchen extractor fan is on. Its a six inch icon fan so shifts a lot of air. I'm considering instead of opening the kitchen window opening the porch window as this will provide cross ventilation. Dragging more air out than just opening the kitchen window.

We only have a small bathroom with a towel radiator so it would be difficult drying an abundant amount of washing. I've removed the chimney sweep as this excessive amount has only occurred since them. I'm guessing its better to leave the air brick alone and leave the chimney as it is as this gives us natural ventilation?

 

[JohnD]

We use a dryer but for big bulky things like towels we stick them on the radiator

This is an attempt to save money?

You can get roll-out washing lines that are mounted over the bath. You can fluff them up by finishing in the drier.

Wet washing draped on radiators is a terrible source of damp.

If you don't stop you will never be free of it.

 

[Michaelsf90]

We do run the dehumidifier while the washing is on the radiator to remove the excess moisture. It's finding the balance until kids are old enough and gone and their isn't as much washing to do haha

 

[Harry Bloomfield]

We use a dryer but for big bulky things like towels we stick them on the radiator and put on the dehumidifier. The smells from outside only occur when the kitchen extractor fan is on. Its a six inch icon fan so shifts a lot of air.

As everyone on here will try to tell you, drying clothing of any type indoors, is a terrible thing to do, drying on radiators is particularly bad for the radiators, because it will cause them to rust. My own solution to drying indoors cheaply, is a series of lines, a dehumidifier, a fan to move the air around, and in all in small room - the door to which is kept closed, whilst there is washing being dried.

 

[Michaelsf90]

The only small room we can put them in is the utility room with a polycarbonate roof so that's a bad idea as it's the coldest room in the house and the dehumidifier isn't as efficient at lower temperatures. We dry them in the dining room which is quite large but the only viable option. How long does it roughly take with the dehumidifier for you? It takes longer than 4 hours and requires the moving of the airer and dehumidifier so it's blowing on different clothes. The dryer is the easiest option just the most expensive unfortunately

 

[JohnD]

The only small room we can put them in is the utility room with a polycarbonate roof so that's a bad idea as it's the coldest room in the house and the dehumidifier isn't as efficient at lower temperatures.

You could put stuff in there and ventilate it.

Above freezing point it will dry.

 

[Harry Bloomfield]

How long does it roughly take with the dehumidifier for you?

We run it overnight, in our utility room, which is the coldest room in the place. I have 6 or 8 lines, running around 10 feet along the room, with an oscillating fan blowing along the lines. The room does have a radiator, but it's set on minimum, and the heating it never triggered during the night. It's done overnight, because the hanging washing blocks the room up, but it does manage to dry two or three washer loads each night.

When ever possible, we time the washing, so the drying can be done outdoors, where I have 40 metres of 'rolling line' - a counter-balanced set up, all stainless steel. You crank the line down, to load/unload, and just push/pull the continuous-loop line along, all from one position, on a patio area. Beyond the patio area is grass, which at this time of year becomes wet and can be quite muddy - hence the 'rolling line' arrangement. It's counterbalanced by a heavy weight, on a pulley, running inside a soil pipe. Cranked down, the line comes to within arm's reach, cranked up, it rises the house eaves height, where it takes full advantage of any sun and wind.