How to reduce humidity in north facing wall

mikelata · 09-01-2014 03:28PM #1

Hi all,

The front of my house is north facing, and the humidity in the rooms (kitchen and master bedroom) that are located on that side of the house is mad.

We bought that house 5 years ago, and during the initial renovations the master bedroom wall vent was blocked with plaster...

We have got into the habit of opening the windows every day right after waking up to improve the ventilation and reduce condensation. However, the improvement is being quite moderate. We came back after 10 days away and the walls were wet , and the white paint of the wall has stains and is getting darker. Your fingers will get wet when touching the walls if you see what i mean...

Do you have any ideas of what we could do? We have already tried special paint but the results were quite humble again. Should we reopen the wall vent again?

Thanks

4Sticks · 09-01-2014 03:50PM

sometimes the answer is in the question

mikelata · 09-01-2014 03:57PM

thanks for your answer @4Sticks

I was not living in the house before the vent was blocked. So, I don't know how much humidity there was before the vent was blocked, and whether blocking the vent created the problem

So, probably the question is whether just by having a vent on a wall eliminates the humidity, and whether a vent is a better solution than opening the windows fully 2 hours a day

Thanks

BryanF · 09-01-2014 05:26PM

mikelata wrote: »

thanks for your answer @4Sticks

I was not living in the house before the vent was blocked. So, I don't know how much humidity there was before the vent was blocked, and whether blocking the vent created the problem

So, probably the question is whether just by having a vent on a wall eliminates the humidity, and whether a vent is a better solution than opening the windows fully 2 hours a day

Thanks

Consider a 'mechanical wall vent with RH sensor' ( type that into google)
Also what is the build-up of the wall ?

Handsandtools · 09-01-2014 10:02PM

The problem is, that Irish builders think that only way to get rid of moisture is living in the wind tunnel.
Remember, all air around You is humid, but it condensates only on the coldest surfaces, normally on the windows and that's why the rads has to be placed under windows, to dry them.
If Your wall is colder than window, it means there's need for insulation on the wall and on the ceiling to protect from cold bridges.
Better use vent in the ceiling, allowing the moist air to escape up true the attic and don't cool your room as quick as hole in the wall.
And don't forget heating in the room, so the air is warm and not condense

mikelata · 12-01-2014 08:12PM

@ BryanF , @ Handsandtools ,
Thanks a lot for your helpful replies

I will check the 'mechanical wall vent with RH sensor' , and also the ceiling vent + wall insulation suggestion

Thanks again

BryanF · 12-01-2014 08:40PM

mikelata wrote: »

the ceiling vent

dont install a ceiling vent unless it is piped to the whole way to external - I wont ever suggest venting moist air into an attic - no mater how well vented it is;)

Handsandtools · 12-01-2014 11:42PM

True the attic in to the vent tile, but keep the vent pipes vertical other ways the water will condensate inside and stay in horizontal parts of the pipes.

gman2k · 13-01-2014 12:28AM

Any vent duct in an unheated space should be insulated.

Handsandtools · 15-01-2014 04:23PM

That's the point, other ways the moist condensates inside of it.

mikelata · 24-01-2014 09:59AM

We have 2 north facing rooms affected by the humidity:
- the master bedroom (first floor). The affected wall does not have a radiator, but the room is heated by a radiator in another wall. This is the wall where the vent was covered
- the kitchen (ground floor), which does not have a radiator in any wall. I usually open the windows when I cook to avoid condensation. This wall has never had a vent

I send you a couple of pics to show the wall stains. Those walls were painted last summer

Thanks for your help. Really appreciated

Handsandtools · 25-01-2014 11:54PM

If that's on the ground floor, than there's a possibility that Your DPC is faulty and the moist comes from the ground. What's on the outside of that wall?
Better do the survey to find out real cause of it. It can be expensive to fix the foundation problem.
And normally radiators are fit on the external wall, other ways the heated air from the rad will condensate on the cold unheated surface, like your external wall etc. When radiator are fit on the external wall the heat makes natural air circulation and drys any moist.

hexosan · 26-01-2014 07:20AM

Handsandtools wrote: »

If that's on the ground floor, than there's a possibility that Your DPC is faulty and the moist comes from the ground. What's on the outside of that wall?
Better do the survey to find out real cause of it. It can be expensive to fix the foundation problem.
And normally radiators are fit on the external wall, other ways the heated air from the rad will condensate on the cold unheated surface, like your external wall etc. When radiator are fit on the external wall the heat makes natural air circulation and drys any moist.

I can confirm this because very radiator in the house I'm in is on an internal wall resulting in condensation running down the external wall surface.

mikelata · 26-01-2014 01:04PM

hexosan wrote: »

I can confirm this because very radiator in the house I'm in is on an internal wall resulting in condensation running down the external wall surface.

Good to know guys

mikelata · 26-01-2014 01:07PM

Handsandtools wrote: »

If that's on the ground floor, than there's a possibility that Your DPC is faulty and the moist comes from the ground. What's on the outside of that wall?
Better do the survey to find out real cause of it. It can be expensive to fix the foundation problem.
And normally radiators are fit on the external wall, other ways the heated air from the rad will condensate on the cold unheated surface, like your external wall etc. When radiator are fit on the external wall the heat makes natural air circulation and drys any moist.

Outside, we have a very standard tarmac driveway, where we park our car
What do you mean about the survey? Getting someone to carry a diagnosis in-site of the problem?

Thanks a lot for all your help

Handsandtools · 26-01-2014 09:05PM

Yes, I mean get a qualified builder or engineer or site surveyor to do the survey on site. This can involve some of your wall being cut or hole being drilled to find the real source of problem.

Handsandtools · 26-01-2014 10:03PM

If you are lucky, and cause of Your problem is moist air condensate in the bottom part of the wall, than the cost of fixing it is low, but if the problem is in DPC, than You need to be ready for expensive job to be done.

mikelata · 27-01-2014 11:18AM

Ok. Thanks

Do you think that there is any point to first try to open up the vent of the first floor wall, and also using electric heaters on the external wall of both the first floor and ground floor, to see if the condensation reduces?

Than, if that solves it, I could get radiators on the walls
What do you think?

Also, are air vents used in all floors?
Is opening the air vent an easy DIY job?

4Sticks · 27-01-2014 11:46AM

Try sleeping with a partially open window for a week and see what happens. The amount of vapour one exhales during sleep is a fair factor here.

4Sticks · 27-01-2014 03:02PM

Have you changed any habits in recent times vs when you first moved in that have increased the moisture load in the bedroom

eg

do you now allow a pet dog sleep in the room. or have you put a fish tank in there ?
have you started drying clothes in the bedroom
have you started to use the en suite extract fan less than you did before
in the kitchen are you boiling foods more than you used to

or

perhaps the extract ducts from your extract fans have become damaged or detached and moist air is being dumped inside - not fully extracted to outside.

Eliminate simple things first.

Handsandtools · 27-01-2014 08:21PM

You can try to dry it with heaters and get dehumidifiers, but You still have to find source of moist. Did the mold is only on the ground floor? If the wall is dry lined, than cut the 500x500mm hole in the plasterboard and check did wall behind is wet as well, so did the moist comes up from foundation or it just condensates in the plasterboard?

mikelata · 30-01-2014 10:15AM

4Sticks wrote: »

Have you changed any habits in recent times vs when you first moved in that have increased the moisture load in the bedroom

eg

do you now allow a pet dog sleep in the room. or have you put a fish tank in there ?
have you started drying clothes in the bedroom
have you started to use the en suite extract fan less than you did before
in the kitchen are you boiling foods more than you used to

or

perhaps the extract ducts from your extract fans have become damaged or detached and moist air is being dumped inside - not fully extracted to outside.

Eliminate simple things first.

Thanks for all your suggestions. We did not change any home living behaviour I think.
As i said, the big thing we changed right after we moved in was closing the air vent in the first floor bedroom walls.
The wall facing south is fine, the wall facing north is not

We removed the existing wallpaper to plaster the walls, and i don't remember noticing that they were invaded by dump

Thanks a lot for your help and suggestions

mikelata · 30-01-2014 10:18AM

Handsandtools wrote: »

You can try to dry it with heaters and get dehumidifiers, but You still have to find source of moist. Did the mold is only on the ground floor? If the wall is dry lined, than cut the 500x500mm hole in the plasterboard and check did wall behind is wet as well, so did the moist comes up from foundation or it just condensates in the plasterboard?

thanks for the suggestions. I don't feel really comfortable with DIY, but we might get some work done in the house, and it might be good to check that out at the same time

also, we might do work in the drive way in front of the house, were the damp is coming from. Should I also take that opportunity to check things out from the outside of the house?

thanks a lot

BryanF · 30-01-2014 11:07AM

mikelata wrote: »

the big thing we changed right after we moved in was closing the air vent in the first floor bedroom walls.

open the vents again

How to reduce humidity in north facing wall

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