Insulating an attic , need advise please

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heretohelp

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We are insulating the attic and are going to use 8 inch insulation , we need to know is this the right size to use ? house is a three bed bungalow , storage heating, very cold house ,
thanks in advance
 
Most experts seem to recommend 300mm (12) inches if you're using fibreglass insulation. I presume you're insulating between the joists in the attic over the bedrooms? 8 inches (200mm) is very good amount of insulation and if you can only get 200mm fibreglass, you can always top it up with 100mm more after. Don't compress it! This reduces the insulating quality of the fibreglass. Also, if there's some insulation there already, remove it before you put in your 8 inch fibreglass and then place it back down on top of the new stuff. If you leave it underneath it, it could become compressed. With storage heating in your house, you would be well advised to use the thickest amount possible to hold the heat in the house all day. A builder friend of mine reckons a house could never have too much insulation.

If you go into Key Posts in Homes and Gardens, you'll pick up lots of relevant info. Good luck.
 
Hi Heretohelp,
The problem with mineral fibre is there are to many questions about this material from health to sustainability, and just how effective it actually is as an insulating material.

If you look up the Irish Agrement Board for which materials have been tested for there use in an attic, the only fibrous material which holds a cert is blown Cellulose, this needs to be used with ventilator trays at the soffit, if tested would mineral fibre be any different.

Also if you use mineral fibre it means you can not use your attic for storage without more expense to store above the insulation by shelving or a raised floor, try to use a system which has agrement from the IAB, or the BBA in the UK, the cost effectiveness should be based on, will it give the advertised U-value, and will it last for the life time of the building.

Mineral fibre will do neither, I hope this helps
 
heretohelp said:
We are insulating the attic and are going to use 8 inch insulation , we need to know is this the right size to use ? house is a three bed bungalow , storage heating, very cold house ,
thanks in advance
Click to expand...

1 used hydrotherm high denisity foam you cut it to fit between rafters it is easy to cut using a hand wood saw you can trim it if needed with a bread knife makes a big difference is expensive though I used 4 inch as this was the depth of the rafters you can simply put floor boards or sheeting over the rafters if you want as it is level with the rafters
it should be avaible in any builders providers be sure to get the high denisity one not just aeroboard though
 
A question for V and Adder.

Any idea what thickness of fibreglass insulation would correspond to the 4 inch hydrotherm high density foam?
 
Lex Foutish said:
A question for V and Adder.

Any idea what thickness of fibreglass insulation would correspond to the 4 inch hydrotherm high density foam?
Click to expand...

V, I just saw your post from earlier today to the similar question I recently posed!!!!!!!!!!

Many thanks,

Lex.
 
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