Loft insulation question - possibly silly
Discussion
Loft has insulation but it is old and filthy following a new roof some years ago. We would like to board the loft to make it more useful for storage and line the inside of the roof to keep the dirt from coming in. I note that 270mm is the new 100mm for thickness of insulation and have no problem with that BUT.....
is that thickness of insulation as effective when compressed under boards or does it need to be fluffed up to its full depth.
is that thickness of insulation as effective when compressed under boards or does it need to be fluffed up to its full depth.
You can leave the exisitng 75-100mm insulation between the joists and then add a rigid insulation board over the top, which I believe should be strong enough for storage. Big thing - make sure you don't block eaves ventilation around the edges of the loft or you'll get probs with condensation.
andy43 said:
You can leave the exisitng 75-100mm insulation between the joists and then add a rigid insulation board over the top, which I believe should be strong enough for storage. Big thing - make sure you don't block eaves ventilation around the edges of the loft or you'll get probs with condensation.
You may well cause condensation problems if you do this, anyway.Without boring you with too many of the technicalities, the most basic rule to avoid interstitial condensation is that you should never put anything with a high vapour resistance on the cold side of an insulated element of the consruction.
Both rigid insulation and timber 'boarding' (I assume that you will in fact use chipboard sheets?)have a high enough vapour resistance that they will trap a significant amount of water vapour within the fibreglass insulation, where it may condense in cold weather and cause damp.
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