Mould in attic!!

the goon

Just looking for some advice. Got our attic insulated in October under SEAI scheme. Was up there over Christmas and saw that in between the rafters there is some white mould after developing. Does anyone know what is causing this?

homer911

How exactly was the attic insulated?

Do you have anything venting into the attic?

Are the soffits blocked with the new insulation?

the goon

Hi, it is rolled insulation. I think ventilation might be an issue. As far as I can tell I don't think there are vents. The house was built circa 1990.

owen85

check to see if you have vents penetrating through roof tiles, checks to see if you have vents in soffits....do this by going outside and having a quick look up, no ladder necessary.
if there are no vents, id vent and see if that helps matters. it should fix the mould problem.

2 options i guess:
either more vents thought the roof tiles....i think 3 up and 2 down on either side of the roof is recommended as it means you get good cross flow ventilation. perhaps someone on here could varify if its a good idea to not place so many vents on the north facing part of the roof. depending on size or attic, you may not need all the vents. if youre worried about the attic becoming cold, but want to keep good airflow and a healthy roof, perhaps a layer of insulation between the attic joists would work for you.

another option is,
if there are vents in the soffits, (you can tell by having a look up outside of the house), the new insulation in the attic may have blocked up the venting route in the attic...you can buy cheap rafter vents that should do sort this out for you. this is the cheaper option and you could do it yourself if the guys you had in are proving a boll**

you also dont want the insulation to be layed messily. by that i mean that is isnt scrunched up in parts, loose in others. you also dont want gaps between rafters and insulation.

a few pics posted may help people here OP

Outkast_IRE

Common cause is the airflow from the soffit vents getting blocked by the rolled insulation. That would be my first check anyway.

sky6

Is there a Shower venting up into the attic space. ? some people think it's ok to just vent into the attic space without consequence. Showers should always be vented by ducting all the way to the Eaves.

the goon

Thanks Owen/Outkast. I had builder buddy come and have a look at it. The attic has zero vents. It was also vacant for about a year before we moved in. I'm hoping that the lack of vents/attic insulation is what caused it. Anyway he is going to put in some vents for me. Thanks for the advice.

Re the pics, I did try to upload some but my technical nouse let me down and I gave up!

the goon

There is no shower venting into attic, just there is no venting of any sort up there!

jack of all

Lack of adequate ventilation is certainly to blame in your case, which could be remedied with circular vents installed in the existing soffit by drilling out with an appropriate holesaw. Also need to ensure that at least a 50mm gap is left between top of insulation and roof felt/ underlay at eaves to allow air to flow over the insulation, otherwise vents are redundant. If you have shower extracts venting into attic space or unenclosed downlighters these can provide a ready path for moisture laden air to find its way into the attic space.

As a general observation there are a lot of companies offering home insulation with references to "SEAI approved" etc- unfortunately a good number of these do not understand or make reference to the building regulations and the Technical Guidance Documents that provide important information on how to comply with these. I had a cocky salesman try to push some home insulation package on me a few years ago and when asked some straightforward questions about the products and service he was proposing he couldn't answer them and was clearly ignorant of basic good building practice. If you're getting significant insulation work done it would be advisable to have a competent person or a building professional advise you, there are too many operators out there with scant knowledge of what they are selling! At least you've identified a problem, many people would rarely venture into their attic and a lot of damage could be done over the course of a year or two.....

the goon

Thanks for the advice jack of all. In fact I am going to print it off and discuss with said builder.

Calahonda52

A simpler idea may be to leave the insulation as is and install some roof tile vents to facilitate cross flow ventilation in the attic space.

Is the cold water tank covered?
Another source of damp is evaporation from it caused by the sun heating the attic space.
I think you will find the vents idea a little easier to do as most soffits are in accessible from inside so to do it properly means stripping off 3 or 4 rows of tiles, they slate lathes and the felt..., if u have hip roof its even harder

the goon

Thanks again. We were looking at putting in some tile vents