loft insulation

11 Oct 2005
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United Kingdom
Hi i recently boarded out my loft to use as a storage/ music studio/ guitar room. i fixed 7x2 joists to the existing 3x2. the new joists span from the wall plate to the stairwell. i then insulated between the joists with spaceblanket i used a 240mm and a 120mm (i think these are the right sizes, anyway i am over the required thickness). i then used conventional tongue and groved floorboards over this.

About a week ago when we had really warm weather it was unbearable in the loft but the rest of the house was fine. i this beacuse of the insulation ? do i need to insulate the roof also? any advice would be greatly appreciated (sp)

Many thanks

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so are lofts generally hot or would moving the insulation from the floor and putting cellotex in the rafters solve the pronlem?


You have insulated the loft floor to stop heat moving betweeen the house and the loft.

But the slates or tiles are exposed to the cold in winter and the sun in summer so the temp in the loft will swing wildly.

Yes you will need to insulate the rafters to control the temp inside the loft.
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cheers johnd so would you remove the underfloor insulation (would this help keep it cool?) or just add more insulation at roof level. i seem to remeber a thread on this subject but cant seem to find it.

thanks again

Add more in the rafters. Don't remove existing insulation if you can possibly help it. If your roof is unfelted allow for lots of ventilation as water will blow in between the tiles. If it is felted allow for lots of ventilation anyway.
thanks again johnd. the roof was replaced about 8 years ago and is underfelted. so should i fix some timber to the rafters (to allow an air gap) and then use cellotex or something? would this help keep the heat out ?


this isn't a job I've had to do myself, so will keep quiet and wait for someone cleverer!

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