Loft insulation

LSainsbury · 10-08-2008, 09:55

Hi,

We want to board out or lost so we can use it for some storage.

The instulation is very thick and comes above the joists.

We've been told that we can just board it out and crush the instulation down but in my oppnion, that negates having 8" - 12" worth of instulation and it wouldn't be as efficient as the air has less surface area to be trapped in.

We also been told by somebody else we could just get some 4" x 4" battens and riase the joists and then lay the floorboards on them.

Which way would you do it?

I think option is the best way!

**Kymmy** · 10-08-2008, 10:07

Yes but by boarding it you're stopping air flow anyway that the 8-12" was designed to stop so in respect think of it as the difference to a brick wall with foam insulation spread onto it which is not as effective as foam insulation injected between two layers of bricks..

So go for it

alferret · 10-08-2008, 10:27

We have 250mm of insulation in our loft, (75mm joists) I boarded around 100 sqr ft by compressing the insulation and screwing the board down to the joists, is it a detriment to the insulation I doubt it. If worried you could extend the height of your joists so there is less compression (done that in another property I owned), lots more work involved and the cost's are more too.

WHISTLED · 10-08-2008, 10:34

Compressed insulation still has the same mass though doesnt it.

Taf · 10-08-2008, 10:37

Reduce the depth of your insulation and you get marked down in any HIP you get in the future I reckon.

---------- Post added at 10:37 ---------- Previous post was at 10:36 ----------

Quote:

Originally Posted by WHISTLED

Compressed insulation still has the same mass though doesnt it.

It's the static air content that does the insulation... so compress it any you reduce the air...

10-08-2008, 10:47

If you don't mind me asking Lee, How big is it (your loft) and how much is it going to cost you to do?

**Kymmy** · 10-08-2008, 11:29

Quote:

Originally Posted by Taf

It's the static air content that does the insulation... so compress it any you reduce the air...

And if you board over the mass then the air is even more static....

It's like putting a cagool over a warm jumper for a simple analogy

LSainsbury · 10-08-2008, 11:49

So the general idea whould be to raise the boarding so it dosn't crush the insulation then..

OK - might cost a bit more - how much can some 4" x 4" timber and some screws be in realation to having decent insulation...with today's eneergy prices it's worth spending the extra few pounds on some timber and di it correctly.

RUSTY · 10-08-2008, 12:11

google for.... Home Insulation - Home Insulation Thermal, acoustic, fire and sustainable stonewool insulation from Rockwool Ltd

Hom3r · 10-08-2008, 14:38

IIRC loft insullation can be compressed and still keeps is rating.

all you need to do is put the insullation between the rafters, this can be one or two deep on top of which you can get a chipboard tongue and grooved which you put down much like lamiate flooring.

DaiNasty · 10-08-2008, 21:08

Quote:

Originally Posted by Hom3r

IIRC loft insullation can be compressed and still keeps is rating.

all you need to do is put the insullation between the rafters, this can be one or two deep on top of which you can get a chipboard tongue and grooved which you put down much like lamiate flooring.

One caveat here, from bitter experience..

before you go and buy a whole shipload of chipboard panels be careful to check they will fit through your loft access hatch.

LSainsbury · 10-08-2008, 21:17

Quote:

Originally Posted by DaiNasty

One caveat here, from bitter experience..

before you go and buy a whole shipload of chipboard panels be careful to check they will fit through your loft access hatch.

LOL! Already thought of that!

Harlquinth · 28-02-2011, 19:07

Hi,

I have some similar issues with my loft which I'm currently looking at boarding in a place I've recently moved into. At the moment it's a bit of a mixture - the central section is boarded, one of the outer sections is very heavily insulated (so that the fibrewool actually covers the rafters), and the other outer section has very little insulation (although it does have a large roll of fibre, so it looks like it was planned, but didn't get done).

The rafters are currently 95mm - my aim is to board the outer two sections for more storage, and it would probably make sense to do the insulation at the same time. The main thing I'm not sure about is what to do with the side where the rafters are covered by the insulation - is it going to be easier to cut/trim (or push) it back so I can get at the rafters to extend them upwards, or should I just board over the top and let the boards flatten it all down?

Thanks, Peter.

martyh · 28-02-2011, 20:33

Quote:

Originally Posted by LSainsbury

Hi,

We want to board out or lost so we can use it for some storage.

The instulation is very thick and comes above the joists.

We've been told that we can just board it out and crush the instulation down but in my oppnion, that negates having 8" - 12" worth of instulation and it wouldn't be as efficient as the air has less surface area to be trapped in.

We also been told by somebody else we could just get some 4" x 4" battens and riase the joists and then lay the floorboards on them.

Which way would you do it?

I think option is the best way!

You are quite correct compressing loft insulation reduces it's efficiency dramatically it needs the trapped air between the fibres to work .Loft insulation is made in different thicknesses to accommodate different depths of joist .In your case since you have loft insulation in place already then you will be able to separate the layers to just above the joist and fit t&g chip board over the top .Depending on how thick the joists are and what you will be placing on them depends on whether or not you will need to strengthen the joists with additional timber .

Last year i replaced a customers boarding in their loft because they had compressed the insulation from 250mm down to 75mm cracking the lath and plaster ceiling underneath plus they shoved that much in the loft in one area the weight was too much for the 75mm (3inch) joist

---------- Post added at 20:33 ---------- Previous post was at 20:27 ----------

Quote:

Originally Posted by Harlquinth

Hi,

I have some similar issues with my loft which I'm currently looking at boarding in a place I've recently moved into. At the moment it's a bit of a mixture - the central section is boarded, one of the outer sections is very heavily insulated (so that the fibrewool actually covers the rafters), and the other outer section has very little insulation (although it does have a large roll of fibre, so it looks like it was planned, but didn't get done).

The rafters are currently 95mm - my aim is to board the outer two sections for more storage, and it would probably make sense to do the insulation at the same time. The main thing I'm not sure about is what to do with the side where the rafters are covered by the insulation - is it going to be easier to cut/trim (or push) it back so I can get at the rafters to extend them upwards, or should I just board over the top and let the boards flatten it all down?

Thanks, Peter.

The insulation should always be in between the rafters if you just try to board over insulation that is covering the joist the boards will not sit correctly as the insulation will not compress to zero mm

**Rob** · 28-02-2011, 21:43

You might want to consider replacing quilt insulation with rigid foam insulation board. It's now readily available from good DIY stores such as wickes. That will save messing about with raising rafters.