How to address my humidity issues

Aloysius1972

someone came to take a look today and will quote me for a loft heated PIV plus a continuous extractor in our kitchen diner. He said that would assist air flow in the property and whilst the PIV might not reduce RH readings all that much it would ‘deal with the spikes’. About £1800 all in. This seems a bit expensive but not wildly so.

I checked the rooms today and the unheated room with window open has some mould already growing on the newly plastered chimney breast.

There is only 2 or sometimes 3 of us in the house so we don’t create a lot of moisture given the house size. We mostly shower at the gym, so the kitchen which is open to the main living space seems the obvious place to extract. We have a heated clothes airer which will be a culprit so we will try to use it a bit less and try to open the window more when clothes are drying. Also maybe assist with a small dehumidifier in that room.

the PIV seems a good idea as the two rooms that will face the landing it’s on are the main mouldy areas. I think these attic rooms have been acting as a kind of ‘natural dehumidifier’ drawing the moisture up there and preventing too much mould elsewhere given that humidity in the house is persistently high (76% at 16.5 degrees today upstairs).

WIAWSNB

Aloysius1972 said:

someone came to take a look today and will quote me for a loft heated PIV plus a continuous extractor in our kitchen diner. He said that would assist air flow in the property and whilst the PIV might not reduce RH readings all that much it would ‘deal with the spikes’. About £1800 all in. This seems a bit expensive but not wildly so.

I checked the rooms today and the unheated room with window open has some mould already growing on the newly plastered chimney breast.

There is only 2 or sometimes 3 of us in the house so we don’t create a lot of moisture given the house size. We mostly shower at the gym, so the kitchen which is open to the main living space seems the obvious place to extract. We have a heated clothes airer which will be a culprit so we will try to use it a bit less and try to open the window more when clothes are drying. Also maybe assist with a small dehumidifier in that room.

the PIV seems a good idea as the two rooms that will face the landing it’s on are the main mouldy areas. I think these attic rooms have been acting as a kind of ‘natural dehumidifier’ drawing the moisture up there and preventing too much mould elsewhere given that humidity in the house is persistently high (76% at 16.5 degrees today upstairs).

I can't reply, as I've left the forum.
Could you post a pic of this mould, please? 

Aloysius1972

Wiped it off unfortunately. It was dark green dusty spotting. Let’s see if it comes back,

WIAWSNB

Thanks. Yes, please keep reporting.
Actually, could you post a pic and just indicate on it where the mould appeared?

twopenny

I've only once had a problem and that was when I was trying to save money by turning the heat off in unused rooms and keeping the doors closed.
Horrified because when I did go in there was mould on handles, books and some wood surfaces. 

Have you blocked off all sources of ventilation and got double glazing?
Old houses had natural ventilation from several sources. In winter even I have the bedroom window open a tad during the night when the heating is off, doors open for a while on decent weather days and dry clothes inside - but again, open the window occasionally.
I did read that it only takes less than 10mins for the air to exchange for fresh in a room. 

WIAWSNB

twopenny said:

I've only once had a problem and that was when I was trying to save money by turning the heat off in unused rooms and keeping the doors closed.
Horrified because when I did go in there was mould on handles, books and some wood surfaces. 

Did you leave the windows open? 

WIAWSNB

Two other things to ponder about what's happening with Aloys' mould.

If we were to remove Aloys' chimney breast in one piece, drag it out to his garden and erect it there, and then build a canopy over it just to keep the rain from hitting, would it go mouldy? No.

And, folk are recommending PIV systems, which I do read good reports about. But, what do they do? Yes, they draw in a relatively small volume of air from outside to gently flush the house and increase its ventilation. They don't first 'dry' the air, or even warm it (well, some do, but not for a greater effect, but just to counter the heat loss from the house air being ventilated away).

So, a PIV is effectively a whole-house open window

I suspect that Aloys' chimney mould has a specific, unrelated, cause.

Aloysius1972

WIAWSNB said:

Ventilate the room fully, keep the inside door shut, and leave off the heating.
That will work.
You won't have condie on your windows, and you won't have mould on your walls.
I stake my nonexistent repute on it.
If I'm wrong I will leave this forum.
And come back as someone else...

Here is the photo marked with the mould affected area. I am not drawing any major conclusions from this as the green mould appeared towards the edge of the boarded and plastered chimney breast where it met the edge baton. Hence possibly still drying out and colder than the rest of the surface. Still, mould did manage to grow in a fully ventilated, unheated and sealed room.

Aloysius1972

WIAWSNB said:

So, a PIV is effectively a whole-house open window

To an extent, yes. PIV is not extracting any moisture and relies on exterior air being fresher than interior air and less moist for the most part. But, as I understand it, the main difference is that it introduces that air actively so will ‘drive out’ damp interior air to some extent and create fresh air flow which is thought to be helpful vis-a-vis condensation irrespective of humidity level. So it will not do a huge amount to reduce average humidity across the house but it will equalise the levels across the environment to avoid the spiking in cold spots that results in problems. By contrast, windows are a passive approach which are reliant on the balance of the interior and exterior air to introduce changes to the air quality. So helpful to an extent but less reliable overall. At least as far as I understand it…

WIAWSNB

Aloysius1972 said:

WIAWSNB said:

Ventilate the room fully, keep the inside door shut, and leave off the heating.
That will work.
You won't have condie on your windows, and you won't have mould on your walls.
I stake my nonexistent repute on it.
If I'm wrong I will leave this forum.
And come back as someone else...

Here is the photo marked with the mould affected area. I am not drawing any major conclusions from this as the green mould appeared towards the edge of the boarded and plastered chimney breast where it met the edge baton. Hence possibly still drying out and colder than the rest of the surface. Still, mould did manage to grow in a fully ventilated, unheated and sealed room.

Thanks.
90% sure that isn't normal condensation, so is either the plaster still drying out, as you suggest, or penetrating damp from the stack.