Author Topic: Insulating Behind Slopy Ceilings  (Read 11356 times)

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Insulating Behind Slopy Ceilings
« on: September 11, 2011, 05:21:10 pm »
OK, not technically renewables, but it still belongs here!

The upstairs rooms in our house have partially sloping ceilings, roughly as shown in the pic below:



So in other words, starting from the outside, we have a layer of slates, then I presume a layer of felt, then sarking nailed to the roof joists, and then plasterboard attached to the inside of the joists. This leaves a 6" space behind the slopy part of the ceiling which I want to insulate retrospectively. There is enough room to crawl in both above and below the slopy portion, but not enough to handle any large sheets or anything.

One weblink I found {2015 Edit - link no longer live I'm afraid} says
Quote
The sloped ceiling is blocked off, and insulation is blown in around the rafters and attic ceiling, leaving adequate space for ventilation. This is usually a complex job, which involves cutting holes in your ceiling and working in cramped spaces. You may want to hire a contractor to insulate a finished attic which is used for a living space.

My questions then:

1) Has anybody on here managed to insulate the slopy part of the ceiling retrospectively, and if so, how?

2) If using a blown or loose fill insulation, how on earth do you maintain an air gap for ventilation?

3) Any recommendations of companies I should talk to about this sort of thing?

Cheers folks!
« Last Edit: December 30, 2015, 07:05:22 pm by Womble »
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

robert waddell

  • Guest
Re: Insulating Behind Slopy Ceilings
« Reply #1 on: September 11, 2011, 05:27:24 pm »
1 not a scubbie
2 i would presume the size of the material would give an air gap (think apples or oranges in bulk they have an air gap
3 miller pattison there are several others that the name escapes me just now

allyb

  • Joined Sep 2011
Re: Insulating Behind Slopy Ceilings
« Reply #2 on: September 11, 2011, 06:41:55 pm »
Hi Womble
The coomb of your attic room as its called is a nightmare to insulate retrospectivly. There must be a 50mm air gap continously maintained at all times from floor to ceiling. You will probaly find there are bits of wood(dwangs) nailed between rafters and they are against the sarking boards so the air gap is then below the bits of wood if this makes sense. So you do not get the continuity of the air gap. So blowing stuff in will then block the air gap. What we found was easiest was to strip plasteboard insulate with rigid board(Kingspan) and to re plasterboard. Yes more expensive but job done right the first time instead of damp appearing if air gaps not maintained.

Dan

  • The Accidental Smallholder
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  • Joined Oct 2007
  • Carnoustie, Angus
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Re: Insulating Behind Slopy Ceilings
« Reply #3 on: September 11, 2011, 07:45:12 pm »
We did just what allyb said (photo below), but we were renovating the whole house at the time...

allyb

  • Joined Sep 2011
Re: Insulating Behind Slopy Ceilings
« Reply #4 on: September 11, 2011, 07:56:05 pm »
Thanks Dan My main job is a building contractor   :)

goosepimple

  • Joined May 2010
  • nr Lauder, Scottish Borders
Re: Insulating Behind Slopy Ceilings
« Reply #5 on: September 11, 2011, 08:09:53 pm »
Yup, and we're architects and are about to do the same thing - good old Kingspan - reline all your external walls with it and you'll be nice and cosy this winter   ;)
registered soay, castlemilk moorit  and north ronaldsay sheep, pygmy goats, steinbacher geese, muscovy ducks, various hens, lots of visiting mallards, a naughty border collie, a puss and a couple of guinea pigs

allyb

  • Joined Sep 2011
Re: Insulating Behind Slopy Ceilings
« Reply #6 on: September 11, 2011, 08:19:32 pm »
And other brands are available Ha Ha :D

Crofter

  • Joined Jan 2009
  • Isle of Lewis
  • We'll get there!
    • Ravenstar
Re: Insulating Behind Slopy Ceilings
« Reply #7 on: September 11, 2011, 11:21:48 pm »
Reference Miller Pattison:-

The people they had working for them on the Isle of Lewis this year were a clueless bunch of idiots. I had to send them packing before they did any real damage to the house! Beware!
Comfortable B&B on a working Croft on the Isle of Lewis. www.Ravenstar.co.uk

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Re: Insulating Behind Slopy Ceilings
« Reply #8 on: December 30, 2015, 06:59:38 pm »
Well, four years on, we finally got around to doing this!! No, not stripping all the plasterboard off, that's far too much upheaval. However, I think we've done a decent enough job - let me know what you think!

Here's what we started with (view from the loft looking down at the slopy bit):



We couldn't use anything solid like Kinspan without taking down the plasterboard, since the horizontal ceiling joists (is that the right word?) were in the way, not to mention plenty of nails etc sticking through. So.....  we bought rolls of "Supaloft" recycled polyester insulation, from www.roofingsuperstore.co.uk. This was mainly because it was the right width already without cutting, but also because it's nice non-itchy stuff (important since we were going to be getting up close and personal with it!).

The trouble with the supaloft is that it tears really easily, so there was no way we'd have been able to get it down the gap between the roof timbers on its own..... so, I stitched up a 'sleeping bag' out of some old parachute fabric I had left over from another job:



We then slid the insulation inside the 'sleeping bag' and held there using large Bulldog clips.



We were lucky that we had access to both the top and the bottom of the slopy bit in most cases. We got the insulation into position by going up into the loft and dropping a loop of string down on a weight, where it was caught by my willing assistant in the cupboard below (at floor level). He then pulled the whole thing down into the gap, with me guiding and persuading from the top. Then, once it was where we wanted it, he released the bulldog clips and pulled the slippy 'sleeping bag' clear, whilst I held the insulation in place from the top.

Here it is with two 50mm thick layers of insulation in place:



There were also four sections which we could only access from the top, so here I used some old fabric (again, stuff I had lying about), and stitched it permanently around the insulation to make a sort of duvet.



We then pushed it into place using drain rods:



So, all in all we're pretty chuffed. It took a bit of time to do, but we managed to insulate the coombed bit pretty well, and also left an air gap under the sarking for ventilation. What's more, we didn't have to go through all the upheaval of taking down the plasterboard  :thumbsup:.

The upstairs of the house is now far warmer than it was before. It's also warmer upstairs now than downstairs, which used not to be the case. Anyway, I thought I'd leave these photos out there in internet land just in case the methods we used are useful to somebody else someday  :thumbsup:.
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

Creagan

  • Joined Jun 2013
Re: Insulating Behind Slopy Ceilings
« Reply #9 on: December 30, 2015, 11:51:36 pm »
That's very clever! I had to do similar but used Kingspan, fortunately the gaps were clear enough to allow this.

Oh and re: Miller Pattison, they told me I would need a vent in the wall because of my woodburner, but I knew the regs already and as it was under 5kW didn't need this... they were pretty insistent and even went down the route of "you might as well remove it since it's only for decoration anyway" which did not go down well with me :D

 

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