Attic Insulation Retro-fit

S

shano25

Guest
Hi Guys,

New to this forum so go easy on me... :)

I moved into our curent house 6 years ago and the attic had already been converted.

With the advent of a population increase in our house coupled with a need to better utilize space, I'd like to insulate the attic space properly so that my kids can sleep in it.

Typically its quite cold in winter and roasting in summer but until now I'v just used it as an office/storage/play space.

I checked out the existing insulation as much as I could and here's what I observe.

There is about 100 mm of old fibreglass on the floor in between the joists and 50 mm of aeroboard behind the stud wall between the attic space and the storage area

My questions are as follows:

What is the best thing to put behind the aeroboard ?


Do I need to further insulate the water tank (currently has some aeroboards sat around it)?


Any pitfalls, things I should look out for or other things to consider?


Thanks to all in advance


Shane
 
Hi.

You need to leave the air gap as it ventilates the roof space. The best solution is to pull down the ceiling and walls and dump the aeroboard, replace it with 50mm rafterloc. Put 100 in the vertical walls and 100mm in the floor of the crawl space so it forms an upside down U that meets the insulation in the ceiling of the crawl space. It contains polyiso, its three time more insulating than fibreglass and 50% more the aeroboard. Then reslab wit a insulated plasterboard (plasterboard with 25mm poly iso bonded to it) this is 75mm and the equiv is 225 in fibreglass at the thinest place, same with walls but put 100mm instead of 50mm. Inside the crawl space you put 100mm between the rafters with meets the 100mm in the walls, check out the xtratherm website and the rafterloc pdfs. basically you want heat to rise from below into the attic but be not through the ceiling into the crawl space. Any questions let me know.
 
Do you know the actual date of this conversion which you say was already done when you bought 6 years ago?

This conversion is more than likely requried to comply with the building regualtions.

If you put some time into it you can search these forums for information posted on attic condensation due to inadequate venting leading to interstitial condensation.

You should be aware of TGD F as this represents deemed-to-comply practice in this area.

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1647,en.pdf

P. 11 Dia 6 Roof Type D [whichever option] refers.

In particular pay attention to the 50mm air gap detail and the need to adequately ventilate the roof at both eaves and ridge.

Your new insulation-follows-the-roof detail should contain a vapour check.

This is due to be superseded this year by an amended regulation:
http://www.environ.ie/en/Legislation/DevelopmentandHousing/BuildingStandards/FileDownLoad,21942,en.pdf

I'd be wary of assuming your attic has been properly converted as opposed to having been floored out.

Competent people who do these things for a living don't usually leave attic insulation under the flooring.

It keeps the attic colder than it should be and offers little in the way of sound insulation.

You should ask a competent engineer to cast his eye over the timber sizes that have been floored over and see if the necessary upgrade has been carried out compliantly.

Typically this can involve installing new, deeper joists with their bottom faces raised up off the existing plasterboard by say 25mm to avoid "popping" the existing ceiling plasterboard due to deflection from increased load.

You should also consider your access from the lower levels to this space and install any fire resistance that may be required.

Please bear in mind that winder stairs are frowned upon by the building regulations although not absolutely forbidden - min stairs head height is usually 2.0M clear, but some explanatory leaflets from the DOEHLG show 1.9M

There are a whole raft of issued in relation to fire safety that need to be addressed.
http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1640,en.pdf

My colloquial experience suggests that a lot of conversions may have been carried out by people not competent to do so and you should ask an architect or other competent building professional or fire consultant to comment on the work to date.

While rafterloc appears to be a popular choice, you may also wish to consider products by Kingspan and Rockwool.

I have no connection to any of the people or companies producing either of these products or refterloc..

HTH

ONQ

[broken link removed]
 
You must log in or register to reply here.
Back
Top