Working with rockwool in confined space

[jonnypetrie]

I'm planning on heading under my floor to put rock wool between the joists. There's not much space down there, maybe 50cm max to bottom of joist. I'm not really wanting rockwool all over my face under my floor! My plan was to wrap the rockwool above ground in a cheap plastic vapour barrier for the main benefit of easy handling when I down there and also an added benefit of having a better seal.

How does this sound, can anyone highlight any problems with my proposal?

 

[r896neo]

I am contemplating the same and for all the extra it will cost I might buy recylcled bottle stuff instead as its completely non irritant.

You can also get wrapped stuff i.e. mineral wool wrapped in foil but as you'd expect its much dearer.

You don't want to trap moisture in there so any membrane used must be breathable. If you put rockwool between and then a plythene sheet along the base of the joists you will get condensation in there which is bad news.

 

[jonnypetrie]

I've already bought a few rolls to do a trial run. I'm not going to be putting a vapour barrier along the bottom of the joists. I just going to stuff the wrapped rockwool in between the joists and then stick a few nails in through the plastic to keep it in place. If the nails fail then I'll use a cheap plastic mesh along the bottom of the joists

 

[freddiemercurystwin]

Chicken wire is often used as whilst its fairly flexible you can manipulate it to keep the insulation tight up against the boards. Using a vapour barrier sounds balmy tbh I'm not sure how you intend using it?

 

[paul_v]

could you not just lift the floor boards, sounds like a lot of hardwork. 50cm of space to crawl around in might sound ok but once your down there it will be tight and soon get very sweaty

 

[jonnypetrie]

My proposed method is:

1: Cut rockwool to size to fit joist width
2. Wrap rockwool in vapour barrier (this could be anything, plastic sheet is cheap though)
3. Go under floor and fit in between joists
4. Fix to joists or use mesh to secure

The main reason I want to wrap the rockwool up is because there aint much space down there and I don't want it on my face!

 

[jonnypetrie]

Lifting floorboards seems like a lot of hard work! I'm not the biggest guy and quite slim so I should fit. I'm anticipating it getting hot but I'll just do it a bit at a time

 

[freddiemercurystwin]

That's fine in theory though as mentioned working in such a confined space is orrible. Not impossible just orrible. We assume you're not gonna leave the insulation encapsulated in any plastic sheeting or similar cos that would be bad.

 

[jonnypetrie]

yeah I was going to leave it encapsulated.... What are the issues with this?

 

[jonnypetrie]

I suppose I can just take a Stanley knife to the bottom of it before I put the mesh up

 

[freddiemercurystwin]

A barrier between the insulation and the boards could provide the means for condensation to occur within the insulation.

 

[r896neo]

As freddie says, any kind of impervious membrane could lead to condensation and long term rotting joists. You need a mask and goggles at least with a coverall suit preferable too. It gets pretty grim. If you go for the recycled stuff you can do away with the mask and goggles etc which makes it much more pleasant.

 

[JohnD]

the Knauf mineral wool treated with Ecose (sp?) has a slippery feel and is coated to prevent it shedding dust and fibres. I wouldn't use anything else now (and it is much cheaper than the white plastic stuff made from recycled bottles, which I have also tried)

I'd wear a mask and goggles anyway, though, when working in a dusty place.

 

[kjacko]

Is there no way that you can open a 'service hatch' and slide the rockwool slabs along the channels between the joists?

 

[footprints]

Hi jonnypetrie,
I would go with the recycled plastic bottles type as others have suggested, take the fibreglass back for a refund and swap it for the non irritant type. So much nicer to use well worth the extra much better than lying on your back in a cramped space with it falling on your face and starting to itch

Regards
footprints