Loft insulation - advice please

[Caroline1979]

Hello, I’ve started the dreaded job of insulating my loft myself - would love a professional to do it but can’t afford it, I’m currently removing all the rubbish up there and want to prep for the next stage. 
Am I right in thinking I can’t board directly over insulation? 
Can I put new insulation over old insulation? The current insulation is at least 20 years old. 
mum sure they’ll be more questions as I got stuck into it but are there any hints and tips or do’s and don’ts  you can give me to make it as easy as possible? 
 

thanks in advance 
 

 

[Spreadsheetman]

You need an air gap between the top of the insulation and boarding to avoid damp issues. Look at Loftzone Storefloor as a relatively easy solution. They do two versions of the standoffs to suit different insulation depths.
 

As long is the old insulation is in decent condition then I think the majority of people just insulate over the top. If the first layer of insulation is running between the joists, run the next layer at 90 degrees to the joists.

 

Wear a good dust mask!

[Iceverge]

13 minutes ago, Caroline1979 said:

Am I right in thinking I can’t board directly over insulation? 

 

If you're putting stuff up there there'll need to be a supporting structure so not to compress the insulation. 

 

14 minutes ago, Caroline1979 said:

Can I put new insulation over old insulation?

 

Yes. 

 

14 minutes ago, Caroline1979 said:

hints and tips or do’s and don’ts  you can give me to make it as easy as possible? 

 

A good dust mask.

 

Mineral wool is a nicer product than glass wool. This is a good price. 

Knauf Insulation Super Top Up 200mm Loft Roll - 5.61m² | Wickes.co.uk

 

Cover all your skin (including clothed areas) with a thick layer of moisturising cream beforehand. It'll help stop the fibres getting in your pores. If you have them, wear old clothes and consider throwing them away later or washing twice. 

 

Don't put the insulation hard against the bottom of the felt in the roof at the eves. A 50mm gap is needed for ventilation. 

 

If you need to cut say a 500mm strip of insulation, it's much easier to do it when it's still packaged in the roll rather than when it's rolled out. I used a standard handsaw. Even a breadknife would work. 

 

It's no extra work to put in a 200mm roll vs a 100mm roll. Thicker is obviously better. 

 

If you're earning less than I think £31k or someone in the house is on benefits you may be eligible for free installation. 

 

 

 

[ADLIan]

Mineral wool is a general term covering both glass wool and stone wool products. Knauf loft insulation will be glass wool

[Radian]

9 minutes ago, ADLIan said:

Mineral wool is a general term covering both glass wool and stone wool products. Knauf loft insulation will be glass wool

 

Yet the two are very different when it comes to handling. I believe most people find glass wool more irritating than rock wool. I certainly react very differently.

 

I also wonder if if the practice of leaving the underside of any water storage tanks uninsulated still holds? I guess it may depend where you live but I can't remember the last time we had ice here, and the loft still stays a bit above outdoor ambient anyway.

[ADLIan]

Newer glass wool products (not yellow in colour) are normally much nicer to handle especially compared to stone wool. Underside of water storage tanks normally left uninsulated but this can introduce a route for thermal bypass to occur.