Advice Loft Insulation?

[SimonG]

Hi

Not been around for a bit so my apols for not supporting the forum as I should.

Anyway - I am currently doing my loft and installing more loft insulation. Had between 20-30cm to begin with and now have 20-40cm.

I am using eco wool which is made from 85% recycled plastic bottles. Lovely to work with compared to the pink fibre wool that was put in by the builders.

Anyway - my question for you brainboxes.

I currently have filled the gap between the joists and then cross laid 200mm of eco wool to stop bridging.

If I put a third layer of insulation down will the benefits be noticable?

Also I have a area in the loft that is boarded with 100mm of insulation below it - does this discount all the insulation I have put elsewhere? I looked at insulation board but it doesnt appear to be that effective.

Any ideas welcome - I want to make my home as energy efficient as possible but have very very limited funds currently (hence the loft being a quickish win)

[forfismum]

500mm of cake would be nice,'cept it might bring mice........

[screener]

hi SimonG, it looks to me like you are approaching the point of diminished returns. 40 cms is a lot of insulation if the new recycled eco wool has a good insulation value. I haven't heard of it, can you tell us more?

It's important to have as even a level as you can and 30 -40 cms is a fairly high variation. Is some of it blown in? covering the joists and stopping direct leakage is something I'm working at in the house right now too.

I'm not sure what you mean by having a part of the loft that is boarded, is this a floor that was put down, as an attic space? Boards aren't all that good, if they are quite thick and fairly tight together they are better than nothing. If you have room you might consider lifting the boards and making another level of insulation in a raised floor, and still use it as attic space.

[include]

There's a guide on this site about loft insulation you might find handy.

Guide to Loft Insulation - How to make your roof eco friendly - The Environment Site Green Living Guides

[Wobs]

Originally Posted by SimonG

Anyway - I am currently doing my loft and installing more loft insulation. Had between 20-30cm to begin with and now have 20-40cm.

If you put any more on top, not only are you looking at diminishing returns in terms of additional insulation, but you will be reducing the effectiveness of the insulation at the bottom as it will be squashed with less air trapped in there.

I am using eco wool which is made from 85% recycled plastic bottles. Lovely to work with compared to the pink fibre wool that was put in by the builders.

Anyway - my question for you brainboxes.

I currently have filled the gap between the joists and then cross laid 200mm of eco wool to stop bridging.

If I put a third layer of insulation down will the benefits be noticable?

Also I have a area in the loft that is boarded with 100mm of insulation below it - does this discount all the insulation I have put elsewhere? I looked at insulation board but it doesnt appear to be that effective.

Any ideas welcome - I want to make my home as energy efficient as possible but have very very limited funds currently (hence the loft being a quickish win)

The insulation board could be one of the best ways to have insulation between the joists and boarding, but I guess its a pay off between using the area and having ideal insulation. You could raise the joists and have insulation between more wood, but I think the insulation board would be easier.

Have you insulated the hatch? I found sound rigid stuff in a skip which did the job perfectly. Also fitted draft proofing around it as well.

There is insulation you can fit to the ceiling of your loft, although avoid the spray on stuff like the plague.

[forfismum]

I can't do our attic as it has a gang of bats living in it and they were there before i moved in so they have squatters rights !
Luckily we have over 2' of reed on the outside and we can always pile on more if it gets cold.
Gspot never told us how he was getting on with his bread making,maybe he set fire to the house,hence the need to re-do the loft?
To repeat an often used cautionary note,consider what will happen to your water tanks when you completely seal all the heat into your house and you go away on the coldest weekend in history.............

[Wobs]

Originally Posted by forfismum

To repeat an often used cautionary note,consider what will happen to your water tanks when you completely seal all the heat into your house and you go away on the coldest weekend in history.............

Absolutely. I've seen it happen.

Which is why some insulation in the loft ceiling could be an option.

My parents loft once suffered such a fate, as they had some insulation in the ceiling, with hard board holding it up. Unfortunately, there was an area of just over 1 square foot with no insulation in the loft ceiling, and a pipe crossed it. On very cold weekend when they were away, and the heating was off...... You can imagine what happened.

[Claire]

Interesting to read that you got on well with that insulation Simon, it's something I need to do imminently - and that's a good point about the hatch door Wobs, I must remember that too

[screener]

Originally Posted by Wobs

If you put any more on top, not only are you looking at diminishing returns in terms of additional insulation, but you will be reducing the effectiveness of the insulation at the bottom as it will be squashed with less air trapped in there.

Have you insulated the hatch? I found sound rigid stuff in a skip which did the job perfectly. Also fitted draft proofing around it as well.

Just a thought on squashing lower insulation by adding more. I don't think this is a problem in a case like this where the top layer is going cross wise to the ceiling joists. That support will protect the lower stuff.

The blown in insulation like cellufibre, is great for filling in around air leaks but does not have the built in structure to avoid compaction, especially if there is any chance that it can get wet.

[SimonG]

Thanks for all the replies so far.

EcoWool: Eco-Wool Loft Insulation

I really recomend it as its easy to lay and itch free. Has a U value of 0.12 which when compared to the others on the market was good.

The 10cm variation is a bit odd TBH because I have tried to make it as consistant as possible. It may be that it needed settling so I will measure it this weekend.

The boards are standard loft boards and cover a part of the loft around the hatch (which I have changed for an insulated one). I went over joist level and then compressed it a little when I fitted the boards (which are tongue and groove for a tight fit) Around the edges I have overlapped approx 200mm of ecowool. I think when I have some money I will lift the boards and put down insulation board on top of the ecowool layer and then put the boards over that.

I think you are right about diminishing returns though.

Its frustrating that in a house only 10 years old it so woefully inneficient