Mould on ceiling, who to help?

metricspaces

A relative of mine got a 1960s bungalow with cavity walls pumped with insulation and the attic filled with rockwool. Since then, many of the ceilings have mould where the ceiling meets the external wall. Who would be best to employ to look into this?

The house is located in the Donegal area, if anyone has any recommendations for someone up that neck of the woods that would be great. Thanks!

There are no air vents on the windows, and no hole in the wall air vents. Rooms that aren't even lived in have mould on the ceiling - so it's not just rooms with high moisture e.g. bathroom, kitchen.

metricspaces

Any thoughts on this one and what are the options to resolve the issue?

MHRV

I contacted one company who deal with ventilation and they were just trying to push their MHRV systems. But as I understand, a house needs a good level of air tightness for MHRV, which this house would not have.

Background Ventilation

Hole in the wall vents are another option I guess.

PIV

Would PIV ventilation be a better option e.g. https://smartheat.ie/drimaster/ ? PIV is much less hassle and will cost less to install than hole in the wall vents.

This thread here suggest PIV is not a great solution https://www.boards.ie/vbulletin/showthread.php?p=106363592? and to go for MEV?

MEV

MEV just extracts air from kitchen\bathrooms? From what I read you still need background ventilation to draw fresh air in i.e. hole in the wall vents in every room apart from bathrooms?

Are MEV systems "always on"? I've read some have humidity sensors in the each room they extract from, and the system increases the extraction when sensor detects a humidity level increase.

DCV

I'm not entirely clear how DCV differs from MEV. Based on this description here https://superhomes.ie/airquality/ , it seems both extract air from bathroom\kitchen and the only difference with DCV is that it controls how much air is transferred into the building in dry rooms?

BryanF

Discussed some time ago, you need to understand your air-tightness, and current ventilation provided, this should be (with the limited info provided) 4’’ holes in each room + MEV in bathrooms and kitchen.
from there you can determine what is best for your house.
Mvhr would great of the house is below say 2ach,
DCV would be suitable above that, PIV would similar to DCV but dependent on house type.

[url]Https://www.boards.ie/vbulletin/showpost.php?p=109781271&postcount=30[/url]

metricspaces

BryanF wrote: »

Discussed some time ago, you need to understand your air-tightness, and current ventilation provided, this should be (with the limited info provided) 4’’ holes in each room + MEV in bathrooms and kitchen.
from there you can determine what is best for your house.
Mvhr would great of the house is below say 2ach,
DCV would be suitable above that, PIV would similar to DCV but dependent on house type.

[url]Https://www.boards.ie/vbulletin/showpost.php?p=109781271&postcount=30[/url]

Thanks. This is a different house to the post you linked to.

It's 1960s bungalow with cavity walls pumped with insulation,attic filled with rockwool, double glazing PVC windows fitted.

Since nothing was done specifically for airtightness. Assuming pointless doing a test and can rule out MVHR.

Does this boil it down to two options?

1) MEV in wet rooms + hole-in-the-wall in dry rooms

2) DCV

BryanF

Yes

antiskeptic

metricspaces wrote: »

A relative of mine got a 1960s bungalow with cavity walls pumped with insulation and the attic filled with rockwool. Since then, many of the ceilings have mould where the ceiling meets the external wall. Who would be best to employ to look into this?

Clues abound. Where's the hardest place to install insulation? Where the roof meets the walls. What's an installer most likely to do? Lay the insulation where it's easy and ignore laying where things get difficult.

Where is cavity pumping likely to fall short? At the very top of the walls.

Sounds to me like you have a cold spot either in walls or in roof, at the junction between the two. Cold means condensing moisture, means mould.

I'd get someone to have a look at getting roof insulation all the way down over the wall. Might mean soffit offs and the like. But relatively straightforward. And put some hit and miss ventilation in (although most non-airtight houses are draughty enough without)

Calahonda52

As above re the clues.

The problem is very common as u can't retro fit attic insulation properly from the attic hatch

Google ventilation baffles and look at the images.

Solution is to strip off the first metre of roof tiles.
remove slating lathes and the felt and get the insulation fitted properly, incorporating the ventilation baffles..

metricspaces

antiskeptic wrote: »

Clues abound. Where's the hardest place to install insulation? Where the roof meets the walls. What's an installer most likely to do? Lay the insulation where it's easy and ignore laying where things get difficult.

Where is cavity pumping likely to fall short? At the very top of the walls.

Sounds to me like you have a cold spot either in walls or in roof, at the junction between the two. Cold means condensing moisture, means mould.

I'd get someone to have a look at getting roof insulation all the way down over the wall. Might mean soffit offs and the like. But relatively straightforward. And put some hit and miss ventilation in (although most non-airtight houses are draughty enough without)

Thanks! I was thinking there may be more to it than just needing to add ventilation.

When you say "hit and miss ventilation", what is this? Is it just a "hole in the wall vent"?

metricspaces

Calahonda52 wrote: »

As above re the clues.

The problem is very common as u can't retro fit attic insulation properly from the attic hatch

Google ventilation baffles and look at the images.

Solution is to strip off the first metre of roof tiles.
remove slating lathes and the felt and get the insulation fitted properly, incorporating the ventilation baffles..

Thanks. I Googled that. Is this a good image here displaying what you had in mind ?



I see some roofs have vents on tiles, like this image below. Do you need these if you have soft fit vents\baffles like the first image above?