Putting loft insulation above boards

Pagw

Hello, between my upstairs rooms and my loft there is 150mm of insulation covered with wooden boards. I was wondering, in order to top up the insulation, would it make sense to just lay more insulation on top of the boards, since I don't need the space for storage? I don't see why not, but I couldn't find anybody talking about doing this online. I wondered would this way of doing it allow too much air movement for it to be effective?

Boohoo

Pagw wrote: »

Hello, between my upstairs rooms and my loft there is 150mm of insulation covered with wooden boards. I was wondering, in order to top up the insulation, would it make sense to just lay more insulation on top of the boards, since I don't need the space for storage? I don't see why not, but I couldn't find anybody talking about doing this online. I wondered would this way of doing it allow too much air movement for it to be effective?

If you are talking about the loft and you say that you do not need any storage in the loft then if it was me i would take out all the boards and either take out all the old insulation if it's in a bad way or if the insulation is ok then buy some more new insulation and place that over the top of the existing insulation to make the total depth of the insulation at least 270mm or what ever the reccomended min depth is these days.
I am not sure i you qualify for free loft insulation but it maybe something to look into.

Norman_Castle

As its likely there is an open air gap between the current insulation and boards this wouldn't be effective.

Pagw

OK, thanks for those replies.

Boohoo wrote: »

if it was me i would take out all the boards and either take out all the old insulation if it's in a bad way or if the insulation is ok then buy some more new insulation and place that over the top

I agree this would be the proper way to do it, but I would rather not go to the effort/expense of having the boards taken up if I could get as good an effect by putting insulation on top. Plus I may want the storage space in future, and I could get it back by just taking up the extra insulation.

Norman_Castle wrote: »

As its likely there is an open air gap between the current insulation and boards this wouldn't be effective.

Ah, that's useful to know. Is this because the air gap allows air from the loft to circulate underneath the boards and take away heat? I suppose this would make adding insulation on top ineffective if most heat is lost that way rather than conducting through the boards. Do you or anyone else have any idea of what percentage of heat is lost each way?

Norman_Castle

Do you or anyone else have any idea of what percentage of heat is lost each way?

I suspect allowing air to flow under the boards would make insulating on top of them almost 100% ineffective. The heat would simply leak around the edges of the boards.

Grenage

It would still be effective, but probably not quite as effective as pulling up the boards. As Norman suggests, you'd need the air space to be closed - this is probably easy as folk rarely bother with boarding the entire loft space.


I pulled my boards up when I added insulation.