Is it better to lay new loft insulation over old?

Question

My brother is doing our loft, and  wants to keep the old fibre glass insulation that is already down, and put new insulation over this. The reason for this is that because its flattened, he will not fit in 2 lots of new insulation, as it will be above the joists. It also would be dearer to rip the old stuff up. Now this has started an argument between my Mum and Dad.

My questions : - 
1) Is it any more hazardous to rip the old stuff up, than just lay new stuff over it. 
2)Would ripping up old stuff put his health in jeopardy?
2) Does the old stuff have a shelf life? 
3) Would it be better to rip up old stuff, and lay just 1 layer of new stuff?

           Many Thanks in advance to anyone experienced in this

Anthony · Accepted Answer

i work for an insulation company. the professional insulators would lay it on top but they would cross lay it the recommended depth can vary from house to house normally around 10 - 12 inches although adequate ventilation etc needs to be considered. it sounds straight forward but isnt always the case. there is a grant entitlement that you can claim where a professional can come and survey the loft for you free and then have a professional installer fit it with adequate ventilation and they will even insulate the piping/ water tanks and hatch if applicable. see if you qualify hope this will help http://www.energycutter.co.uk/#/insulation-boilers/4570657703

Anonymous · Answer

I spray all my insulation in. It's quicker and a whole lot easier. If your doing this in your attic they recommend about 24 inches.

? · Answer

Lay new insulation on top of old that's the way the professionals would lay it, They also recommend that its laid 90 degrees to the old.

Cashcashjonny · Answer

Unless there is a problem like the old stuff is wet from a fixed leaky roof or it's half-eaten by rodents, just leave it in place and put the new stuff on top.

Health hazards: pulling up the old stuff could make your brother really itchy and irritated and he might loose concentration and put his foot through the ceiling.

? · Answer

Just lay the new on top of the old for increased insulation.

Martin · Answer

I'd think so... Double the thickness sounds like it would have double the impact?....

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Is it better to lay new loft insulation over old?

6 Answers