How do I lay more insulation in my loft?

[WhoDaresWins]

I bought this house recently and plan to lay some more insulation in the loft around autumn time. The reason being is that in places there is no insulation (a strip of floor boards instead with nothing underneath) and in places it’s only around 80-100mm thick. Where it is thicker, there is only one strip and gaps between the rafters and the next strip of insulation.

I guess my questions are:

1. Do I just buy some new rolls of insulation and add that over the top, running perpendicular to the current insulation?

2. When it comes to where the insulation meets roof/eaves, do ensure it touches or do I need to leave a gap? I’m told it’s a sealed loft but I’ve added some vent tiles and some vents between some of the felt strips.

3. I’d also like to add a section of boarding or flooring so I can safely walk down the middle and store a few things, what are some ideal feet to use? And what kind of wood do I use? As I’ll want to make sure there is sufficient insulation underneath

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[Neelix]

Personally I wouldn’t bother raising the floor - just have insulation under the board and bear in mind that wood is a fairly good insulator. Roll at 90 degrees to the existing insulation AND make sure there is sufficient airflow in and out of the eaves or you will get condensation issues.

Also if you have an electric shower be mindful that laying too much insulation over the cable derates the cable capacity

[WhoDaresWins]

Personally I wouldn’t bother raising the floor - just have insulation under the board and bear in mind that wood is a fairly good insulator. Roll at 90 degrees to the existing insulation AND make sure there is sufficient airflow in and out of the eaves or you will get condensation issues.

Also if you have an electric shower be mindful that laying too much insulation over the cable derates the cable capacity

Thanks for help here. Much appreciated. I’ll leave a little gap near the eaves.

I don’t have an electric shower. But there are some cables for lighting laying on top of the current insulation. Is it imperative these cables lie on top of the new insulation?

[yartin]

You have enough insulation, don't put anymore
I made a big mistake years ago, I already had insulation, new thing came out 300mm insulation had it installed on top spoiled the whole loft to unusable and can't go up. I didn't see any improvement, had enough and binned them all, now can go up freely boarded do repairs storage...

[Someone-Else]

You have enough insulation, don't put anymore

I have often wondered that.
I don't see how putting more insulation on what you already have works, if you were going to go outside in a blizzard most of your life, I can understand it, but for a loft that just has "static air" I don't see how adding insulation to insulation* is going to help, unless the heat from burning your money helps?

* Yes, if you only have thin insulation, then yes add some, but if your insulation is already 15cm deep, why add more?