Rockwool and chicken wire insulation - how is it laid?

[sparkybird]

Hi there

I'm having my loft converted and the architect has specified this type of insulation to go under the floor. I want to know how it's laid.

Is the chicken wire cut to fit between the joists, stapled to form a 'basket' and then 1 thickness of Rockwool laid on top?

I have seen in the past the chicken wire run over the top of the new joists, pushed into the space between them and stapled, then the insulation laid. Does this not affect the chip board flooring when it's put down?

Hope someone can enlighten me!

Thanks

SB

 

[mointainwalker]

Having difficulty understanding your query.

If you are having a loft-conversion, why are you insulating under the floor ?

It makes no sense unless you never intend to go up there when it gets cold when the heat rising from below would warm you.

Edit

FYI

The chicken -wire is used on ground-floor installations where there might be a big hole underneath and the mesh stops the fibre-wool falling through.

 

[sparkybird]

Hi

It's used as a fire proofing I understand - ie the chickenwire supports the rockwool to stop it falling onto the floor below.

I don't make the regs - just trying to follow them! As mentioned architect and BC have asked for this.

I've been doing some more searches online and think I have found the answer in a video here anyway...

http://www.above-it-all.co.uk/lofts/loft_floor.htm

Sb

 

[mointainwalker]

Sorry, still makes no sense to me. AFAIK the fibre-wool is for insulation-purposes only. It certainly cannot double-up as fire-proofing as this would then mean that polystyrene would no longer be permitted as thermal-insulation which is absolutely not the case.

Is it possible you are mis-understanding what the BCO and architect are talking about ?

 

[freddiemercurystwin]

Rockwool do make insulation suitable to use as a fire barrier, although I don't think its in any of their literature I think it can be used within floor zones for fire compartment protection. Sometimes the floor between the 1st floor and the loft needs upgrading if it had a lathe and plaster ceiling for example. The chicken wire being required to hold the insulation in place should the fire bring down the lathe leaving no support for the Rockwool. To fix it you'd just tack the wire in position so that the insulation was suspended within the floor zone. As mentioned it is not required by Building Control as a heating insulator, clarification for your Arch is required really.

Unless this is for the area of ceiling (above the 1st floor) between the external walls and the insulated dwarf walls forming the loft? In which case the insulation can just sit on top of the joists.

 

[Deluks]

I have seen in the past the chicken wire run over the top of the new joists, pushed into the space between them and stapled, then the insulation laid. Does this not affect the chip board flooring when it's put down?

Hope someone can enlighten me!

Thanks

SB

How deep are the current joists, are you not getting new ones put in over these to create the new floor?

As you say, form the mesh between the joists touching the top of the ceiling and lay the wool between. Rockwool is an excellent fire stopper. Try burning some!

 

[sparkybird]

Thanks for replies all

The new joists (suspended from the steels) are 9 x 2, so quite hefty and the chicken wire will keep the rockwool well away from the existing lathe and plaster ceiling.

Sorry if I confused the issue by calling it 'insulation' - it's just that every other surface seems to have to be insulated to the n'th degree....

SB

 

[Deluks]

No the rockwool can go directly on top of the l&p, rest it on top of the joists as Fred says only if there's space, doubt it though as you'll need 100mm thickness. pack it in tight, no gaps at all.

 

[sparkybird]

The architect has specified that the rockwool is to be supported by chicken wire, so I think I'd better follow this as I don't want BC to make me redo it.

Does the chicken wire cradle sit well above the existing l and p ceiling (this is what I thought) or should it hang down, touching it? The height from the top of my new loft joists to the l and p is getting on for 11 inches.

Thanks again for all your advice

SB

 

[Deluks]

Sorry, my previous post wasn't clear, as close as you can to the ceiling but defo with the chicken wire beneath. Remember it's to keep the flames at bay, so as low down as poss.