uninsulated space in my loft

[cath123]

Hello

I have recently had my old boiler replaced and a new combi installed which means the old cold water tank was removed from the loft. It was sitting on a little boarded platform and has no insulation underneath (the rest of the loft was fully insulated a year or so before the tanks were removed).

As I now have have a small uninsulated space in my loft, I had the idea of stuffing some loft insulation in the gap between the loft floor and the platform but after looking through this forum I now realise that this is a stupid idea!!!

I don't mind removing the platform if I have to. Do I have any other options...i.e. can I just lay some insulation over the top of the platform (completely coverring it leaving no gaps anywhere) or is this just another stupid idea??

I like the look of Wickes' space blanket as it seems easy to work with - with no loose fibres - and can be laid in layers. Has anyone used this? Fortunately the platform is only small so won't require a lot of insulation.

Please forgive my total lack of knowledge on the subject.

Many thanks

 

[tony1851]

As I now have have a small uninsulated space in my loft, I had the idea of stuffing some loft insulation in the gap between the loft floor and the platform but after looking through this forum I now realise that this is a stupid idea!!!

Why would it be a stupid idea?
If it's a small platform where the tanks originally were, it seems common sense to stuff some fibreglass insulation in the gap between the underside of the platform and the ceiling.

 

[cath123]

I read that the ceiling can bow if the insulation is too tightly packed under the boards (although I can't really see that the insulation is that heavy). The main reason it seems stupid is that people mention air circulation and condensation.

I'm really hoping I'm wrong and it isn't a stupid idea afterall as it seems so easy just to plug up the space with insulation.

 

[tony1851]

The main reason it seems stupid is that people mention air circulation and condensation.

I'm really hoping I'm wrong and it isn't a stupid idea afterall as it seems so easy just to plug up the space with insulation.

The condensation issue only arises when people attempt to cram isulation under the tiles, between the rafters; it isn't a problem on the ceiling.

If your ceiling joists are 3" or 4" deep, just put 100 thick quilt in. This may be thinner than your main insulation but will effect some improvement.

 

[cath123]

Many thanks for your replies.

I have been back up into the loft and realised that the platform is raised about 20cm from the loft floor (rafters on top of rafters). I have seen some insulation in B&Q that is made from recycled bottles (200mm) and so I can cut out a piece (without setting of my daughters asthma) and feed it into the gap. That way I can keep my little platform and have somewhere to keep the xmas decs.

I have also seen some space boards which I could stick onto the platform to add that extra bit of insulation. Has anyone used these?

 

[Humour]

Hi Cath,

I think that all of your considerations are viable. I do not see an issue with adding insulation between the ceiling plasterboard and the platform, provided you do not force it in and do not compact it in that space.

The wool type insulation is meant to be free laid without compression as the air trapped in the fibres provide the insulation properties, therefore compressing it leaves less trapped air in the fibres. For wool insulation to bow the plasterboard it will have to be compressed severely where the insulation provides no more flex and thus passes the load placed above onto the plasterboard it is sitting on.

My advice is to put insulation under the platform as much as you can freely place in there with your hands without putting too much force into the process and compressing it. Then if you wish to add another layer, just lay more on top of the platform as you were suggesting. The recycled plastic stuff is good but its a bit more expensive. I just did my whole loft space with the Thermalfeece ECOGreen stuff and it was a joy to work with compared with glass wool

The idea with spaceboard is that it is cut to size and does not leave any gaps between joists or the space you are looking to cover. To get that done correctly most probably you will need to remove the platform so you can measure and cut for the space underneath.

Just my opinion on the subject

Hum

 

[cath123]

Humour....your opinion is gratefully received. I have now purchased the recycled insulation (£16.48 for a roll so not too expensive) and it's sitting in my kitchen waiting to start this weekend.

I'll have loads left over so I think I'll just put some on top of the platform as you suggest.

Thank you so much.

By the way, what is really interesting is that I have a grey square on my ceiling right below where the platform is. I assume that as the warm air is dragged up into the loft the dust/dirt in the air settles on the ceiling. Once the insulation is in I think a coat of paint on the ceiling is needed. Just goes to show how effective the rest of the insulation is!!

 

[tony1851]

thus passes the load placed above onto the plasterboard it is sitting on.

Doesn't work like that.

 

[catlad]

The shadow you are talking about is due to moisture escaping through your plaster board ceiling and condensing. Just lay the rest of your insulation in the area in your loft you want to keep the warmest.

 

[tony1851]

The shadow you are talking about is due to moisture escaping through your plaster board ceiling and condensing. Just lay the rest of your insulation in the area in your loft you want to keep the warmest.

I don't think it's so much moisture getting through the ceiling; rather, because that area is cooler than the rest, moisture tends to condense on the ceiling (ie on the room face). Because of the slight dampness, it tends to attract dust and hence over time becomes dirtier (ie greyer) than the rest of the ceiling.
Usually known as 'pattern staining', though it's not as common now as in the old days when roof insulation was unknown.

 

[Humour]

thus passes the load placed above onto the plasterboard it is sitting on.

Doesn't work like that.

How does it work then Tony? Some of the load surely is passed through when the material below the load is solid/uncompressible?

Cath, I'm glad you went with the easy option no hassle and no lack of sleep

 

[Humour]

Grrrr! lol this php board is laggy as hell, double post....again

 

[tony1851]

thus passes the load placed above onto the plasterboard it is sitting on.

Doesn't work like that.

How does it work then Tony?

It depends on the relative siffness of each material. Stiffness is partly a function of (1) the modulus of elasticity of the material and (2) the moment of inertia of the cross-section of the material.
Plywood will have a far higher modulus of elasticity than any fibrous insulating material.