Laying loft insulation

takay9

I am an absolute novice when it comes to DIY but I am
planning to lay loft insulation. I have been given a few rolls of 100mm base layer insulation roll - my plan is to lay them between the joists and then layer it up. I know the recommended thickness is 270-300mm so is there any reason why I shouldn’t lay three layers of 100mm? I know each layer needs to be laid in the opposite way but just wasn’t sure if there was a reason not to have 3 layers rather than just 2? Thanks all

tacpot12

No, there is no reason not to lay three layers rather than two. I would lay the third layer either across the second layer (perpendicular to it) or lay it over the joins of the second layer (and along the line of the second layer). 

FreeBear

Got multiple layers of different thicknesses of loft insulation. From memory, 75mm, 150mm, and some ancient 25mm stuff. As ceilings get replaced upstairs, another layer of 100mm fibreglass is being stuffed between the joists - This gets that awkward bit right under the eves covered and kills a potential cold spot.

Just be careful not to stuff too much insulation right under the eves and compromise ventilation in the loft.

breaking_free

Time involved. Putting in 3 layers takes longer than putting in 2. Other than that, can't think of a reason.

JustAnotherSaver

Sorry to hi-jack a bit but why do the regs now say the recommendation is XYZmm vs a few years ago when it was ABCmm? What's the reason for the change? Climate change is supposed to be heating everything up not cooling it.

I remember working for a company years ago selling this when 50mm would be flying out the door. Now that's not even stocked, unless it's the acoustic version. The shift to 100mm as standard and then 150/170. 200 is now more popular than it ever was.

Makes me wonder what we're going to be selling in 20 years time. 500mm??

Same with the rigid sheets like Kingspan. 40mm was the most popular thickness as far as the cavity sheets went from what I can remember. Then 50mm for a long time. 50mm is still relatively popular but 100mm is possibly what is sold the most now.

FreeBear

Building Regulations keep making incremental changes to improve the thermal efficiency of a building. This trickles down to general recommendations - Saving energy is a good thing.

And if you think the UK is going to get warmer as a result of global warming, I fear you are in for a nasty surprise. If when the Atlantic Conveyor (the Gulf stream) gets switched off due to an increase of ice melt, we will freeze during the winter. Summers will be hotter, and we can expect more extreme weather conditions such as the Beast from the East.