Loft Insulation

[SlackAlice]

I've decided on increasing my loft insulation. I shall do the work myself as a reasonably competent DIYer (I hope, famous last words!).

Currently, my loft has fibreglass rolls between the rafters and then boarded over for safety and to allow me to store various bits and pieces, nothing heavy. To increase the insulation to any significant extent, would mean I would have to remove the boarding and increase the rafter height by about 150mm and infill with 150mm rolls and then replace the boarding.

A simpler solution would be to remove the boarding and lay Celotex Insulation board (GA4100) 2400mmx1200mmx100mm directly onto the rafters and then replace the boarding. The boarding is tongue and groove chip.

1) Is celotex insulation board more thermally efficient than fibreglass rolls? I'm hearing claims of almost twice as efficient. I realise I would have to split the boards lengthwise to get them into the loft.

2) After laying the celotex down, can I just float the tongue and groove chip flooring down, or would I need to screw through into the existing rafters? I would glue the joints together to stop separation.

Any comments please, especially if you see any flaws in my plans.

[Old_Geezer]

Just to say my loft has sufficient insulation to fill the gap between the bedroom ceiling and the boards in the loft. I can't say I feel the need to try to stuff more down there. Are you not going to get a sufficiently diminished return that it becomes uneconomic, if you are in much the same situation ?

[Fibonacci]

This might prove helpful.

[The Builder]

100mm of Celotex is approx equivalent to 225mm of itchy stuff...... 2 and a bit times the value.

Floating floors are used all the time Slackers. No need to fix down.
Usually the T&Gs are glued. A Fairy Liquid bottle full of PVA is ideal for squirting it into the grooves. That's in a normal domestic situation. In a roofspace, traffic is so light you could happily leave out the gluing.

It's an excellent idea, and you should certainly feel the benefit.

ps.... anywhere where it's just too awkward to cut and position Celotex, don't forget to stuff with plenty of ordinary loft roll.

Alternatively, I could point you to a special type of itchy roll that has a much higher "R" value (resistance to heat loss), but it is rather silly money I'm afraid.

[SlackAlice]

Thanks for the Answers, much appreciated.

Old_Geezer
I see where your coming from, but I consider my loft insulation to be well below par. I have costed out what I intend to do and think that the cost will be covered in about 3 - 4 yrs, less if the cost of Gas/Electric continues to rise.

Fibonacci
Nice link there. No idea why I didn't look at youtube myself.

The Builder
Thank you for the advice, you more or less confirmed what I considered my best choice, was possible and viable. Now to get cracking!!!

[Jemisa]

MAke sure you use goggles and gloves if you're disturbing the fibre-glass stuff, it can make you sore.
Also if you're 60 or over the council will insulate your loft for you FREE!.

jem

[SlackAlice]

The council will only supply and fit Insulation Rolls over the top off existing Loft insulation, which stops me from boarding over and utilising the loft as a storage area.

Your point about wearing gloves and goggles is good, and I'll definitely be wearing them. ☺

[Jemisa]

I forgot to mention a mask too, you don't want to breathe that stuff into your lungs.

Jem