Attic insulation

Up Donegal

I’m in a storey and a half house that was newly built in 2005 – 2007.
Upstairs is always very hot in warm weather and very cold in cold weather. Any recommendations or suggestions on how I can address this? Extra attic insulation – spray-on insulation/rockwool/fibreglass etc?
The roof is slated over blue membrane and the attic is insulated with fibreglass roll insulation (100mm, I think) between the joists. There is roof space ventilation in the soffits.
Thanks in Advance.

muffler

You would need a minimum of 300mm in the attic between and over the joists. You should look to see what way the sloping ceiling is insulated at present and upgrade that together with addressing ventilation which needs to be maintained. Walls, from floor up to wallplate level could possibly be improved with insulated plasterboard.

There are loads of threads on this topic here and in the construction and planning forum. Also to note that if the house was built 2006 or earlier you might qualify for a grant from the SEAI. I think the date is set by the date of fitting the ESB meter.

Calahonda52

OP, the issue here is both the amount and location of the insulation but, if its in the roof slope then the concept of decrement delay comes into play
https://www.designingbuildings.co.uk/wiki/Decrement_delay
http://www.greenspec.co.uk/building-design/decrement-delay/

then if its just between the ceiling joists you need to have about 400 mm in total, ensuring by the use of ventilation baffles that the air from the eaves does not pass through the insulation.

The only way they can be fitted properly is from outside.

google ventilation baffles in attic and look at images.
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Power cables need to be sleeved and all pipe work/water tanks above the insulation insulated