# 300mm Fibreglass Down, Worth putting in more ?



## ryan-neil (7 Dec 2009)

Hi All.

Jusht a quick query. I just insulated my attic with 300mm of Fibreglass. Previously had 85mm. It has made a huge differance, place above 20c from the storage heaters alone. I have enough left over to put down other 100mm over the entire attic, is it worth doing so though, would it make much of a differance or is 300mm the requirment for a reason such as after that it makes no real differance.

Tanks


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## Sconhome (7 Dec 2009)

It makes very little difference once you go over the 250 - 300mm thickness as other factors such as ventilation requirements come into play.


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## colm5 (7 Dec 2009)

Sconhome said:


> It makes very little difference once you go over the 250 - 300mm thickness as other factors such as ventilation requirements come into play.


 
+1. 

Evaluate your ventilation


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## ryan-neil (7 Dec 2009)

Thanks for the replies. By ventilation do you mean ventilation in the attic or the the property itself.

Thanks


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## onq (7 Dec 2009)

HI ryan-neil
The attic space needs a clear 50mm gap to the eaves vents.
http://www.environ.ie/en/Publicatio...ng/BuildingStandards/FileDownLoad,1647,en.pdf

FWIW

ONQ.

[broken link removed]


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## colm5 (7 Dec 2009)

ryan-neil said:


> Thanks for the replies. By ventilation do you mean ventilation in the attic or the the property itself.
> 
> Thanks


 
Both really. If the air infiltration rate is too high in your property, then you will not be able to hold an internal temperture for long, no matter how much insulation you have.


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## onq (7 Dec 2009)

colm5 said:


> Both really. If the air infiltration rate is too high in your property, then you will not be able to hold an internal temperture for long, no matter how much insulation you have.



Ummm. Yaaas. 

If you don't provide 6500sqm of permanent passive ventilation in each habitable room, then you don't comply with part F.

And if you install one of those new-fangled MVHR systems and forget to fireproof the ducts where they breach the FR30 rating fo the first floor ceiling you could be at risk in a fire emergency.

Dying of cold -vs- asphyxiation and/or being burnt in your bed.

Tough choice.



ONQ.


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## ryan-neil (8 Dec 2009)

Thanks for the info.

Unfortunatly, i have a 2nd floor apartment with an attic above, on an exposed site (set within a park) with three open sides so some days i could fly a kite within the attic. 

I have kept the vents clear so hoefully there should be no damp issues. The ventilation is more intresting though, there are only vents in the bedrooms and an extractor in the bathroom.

Nothing in the sitting room (with open fire) or kitchen . I have added 100mm of Polyiso to the attic door so next is new windows hinges and a stoves as well as recaulking all internal window frames / skirting as per your advise.

Any other tips would be great.

Thanks again.


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## colm5 (8 Dec 2009)

If its that bad you should get someone out to have a look at it, who is experienced in building infiltration etc.. for some professional advice and to examine the actual ventilation and number of air changes per hour in the dwelling.

Ventilation holes were usually made with a lump hammer and so can vary in size. Ventilation needs to be right of course, for many reasons, but if its too high it can make a significant difference on your heating requirements.


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## ryan-neil (14 Dec 2009)

Thanks Colm5 for the advice, i have donated the renaining insulation to a family member.


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