Attic insulation - to cover or start over

E

eoinoc333

Registered User
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Hi,

should I dump the old fiberglass and buy again, or just top up with new rolls?

I have a 10 year old house, and looks like the 4 inch fiberglass insulation is the original insulation.

The question is, would you cover this insulation with another layer of new fiberglass, or just dump the lot and start again?

Originally, it was 4 inch, but it's squashed/torn in places.

The other option is to rip it all, place 100mm between boards then top off with 170mm. I guess this would also require getting a skip to dump the old stuff.

Any opinions on which option to go for?
 
Don't even think about removing the old stuff. You just lay additional layer / Layers on top. Not 100% but I think the minimum specified by the building regs is around 200mm of Fibreglass. just fill the gaps you've mentioned in the old stuff and top off with additional layer. BE VERY CAREFUL NOT TO BLOCK AIR TRANSFER FROM THE VENTS IN THE EAVES, SOFFET BOARDS
 
you're gas said:
Don't even think about removing the old stuff. You just lay additional layer / Layers on top. Not 100% but I think the minimum specified by the building regs is around 200mm of Fibreglass. just fill the gaps you've mentioned in the old stuff and top off with additional layer. BE VERY CAREFUL NOT TO BLOCK AIR TRANSFER FROM THE VENTS IN THE EAVES, SOFFET BOARDS
Click to expand...

+1.
Simply cross lay the new insulation over the joists and the existing insulations. Dont cover downlight fittings and ensure you cabling is not buried in the insulation.
Wrap your tank and lid too, avoid winter freezing of pipes as the attic will now be much colder!
 
I'm in kinda the same boat - I've removed part of the ceiling to install a new pine ceiling and accordingly have loads of old fiberglass insulation piled up in a corner of the room. I will be buying new insulation for this section of the new ceiling but wondering should I try and install the removed old insulation into the remaining attic space to "double up" or should I merely dump it and use new insulation in the entire attic area, overlaying it where I haven't removed the old stuff? Like the previous poster it looks like 1980's era 150mm insulation that with time has "sank" down to about 100mm thickness...?
 
The danger of handling this stuff is the dust and glass fibres that will float up every time it is disturbed. Especially if it has been lying in an attic for 30 years.

If you have to remove old insulation, bag it in-situ, with the appropriate safety mask, gloves, oversuit & goggles to protect yourself. Always overlay if possible.
 
Don't you think that will compress the new insulation and cause it to slump?

Even more so if it gets tramped as you try to overlay it at right angles.
 
Well I got to last night and lugged all the old insulation back up into the attic and relaid it over the existing, 3 layers deep in places so now I have about 180mm of compressed old insulation in 3 layers over one room. A really dirty job, hot, cramped conditions and awful sore on the knees not to mention the dust flying off the stuff, Even with mask and clothes tucked into gloves and socks it's little protection against this stuff especially with the sweat running down yer face to boot, but all in all i'm glad I did it rather than dumping the stuff, all in the spirit of reuse and recycle.

I'll put new insulation into the new ceiling. Is the regular new 150mm considered sufficient for between old style 4" x 2" rafters or should one consider crosslaying a second layer?
 
I would go with a second layer also fit a vapour check on the joists before fitting the pine ceiling, a layer of plastic sheet visqueen or similar will prevent moisture laden air from entering the roofspace this can also cause interstitial condensation in the insulation making it useless over time.
 
I remember putting this insulation up with my father yeeears ago, we wore masks to avoid breathing in the fibres - I think the point of not removing what was already in place would be to prevent the same problem. Not sure what you've achieved by removing and then replacing...
 
hi, just roll over the old insulation, standard is 10inch, i,m an insulator we put in 2 layers of 6inch which brings it up to 300mm, had to laugh to myself suits gloves socks stuffed in, i wear t shirt, best of luck
 
How much does it cost approximately to add extra insulation to an attic house about 1,600 sq ft. Also is it a very dusty job. 2 of my kids suffer with asthma/allergies and would hate for the house to be full of insulation dust. Are there precautions we should take. Also is there a grant for this? Thanks
 
It works out around 8-10€ per m2 for 300mm layer. All depends on your attic access, roof height etc.

Yes, there is a HES grant of €250 available for upgrading the insulation, you also need to have a draughtproof insulated hatch, insulate pipework and water storage tanks. These works would be additional to the rates indicated. There is a requirement for flooring to access the tanks too. Check out the SEI website for full details and accurate info.
 
you wont be able to avail of the grant if you are only insulating your attic.
 
shower with cold water after working with it, hot water will open the pores in your skin and the fibres and dust will drive you potty
 
hi,

I've re-insulated my attic (cut-roof) as follows:
Laid rolled insulation at right angles to existing insulation in 'eve' areas, so going from 4" to about 12", without blocking any of the air inlets.
In the 'wall' section, from the floor to the purlin, added 2in Expanded Polystyrene, leaving an access point on either side
In the sloped wall section, between the rafters, added 2in Expanded Polystyrene, allowing air to flow in behind it

I'm now at the roof section which will be about 2 feet beneath roofline and wonder what type of material to use, in order to sheet it. There are only 4 cross-beams, from which to hang something, on top of which I'd like to add about 8" of rolled insulation. I'm wondering about the load factor?

Secondly, what about ventilation in Summer, it gets hot up there, before this, so, I can only imagine it will get hotter - leave eve access points open?

Lastly, my cold water tank is sitting in this space, and I thought of just insulating it & then putting a wooder frame over around it, easy to access, but just screen it out.

The area will be for storage mostly, but my 16yr old is also looking to make a den up there.

thanks in advance for your feedback...
John.
 
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