ceiling insulation headache

[dalivar]

Started using our first batch of (ready mixed) lime this week! Its good and seems to be successful so far. We're only filling holes and pointing so far but plastering will be a better test.

Anyway, the room we're working on has 50% of the ceiling sloping, directly under tiles with the remaining ceiling being flat with the roof space above it. We have already insulated the roof space, but want to insulate the other part of the ceiling. We are trying to keep as much of the original fabric of the building as we can and if we insulate this part of the ceiling internally with insulated board, we will lower it enough to cover the picture rail. But, if we insulate between the rafters we will lose the lath ceiling. I think insulating between the rafters is prefereble although very messy. What are your opinions? Also do you think its possible to remove only half a lath ceiling or will it all need to come down?
I should also confess that while we're happy to point/plaster a wall with lime, replacing a lath and plaster ceiling is beyond us both so it would be plaster-boarded and skimmed to finish. Its currently covered in artex so its not been untouched by modern coverings.

Thanks..

 

[Feltwell]

I had exactly the same problem, and only got round it by insulating from outside after taking the tiles and battens offs- we were replacing the roof covering anyway. Have you got felt or breathable underlay beneath your tiles? You need to allow an air gap above your insulation - you can't use the full rafter depth for the insulation.

Note that undercladding the ceiling with insulated board will be more effective - you don't get the cold bridge effect from the rafters.

You can indeed take down only part of a L&P ceiling. It is a horrendously messy job though - if you intend to underclad then if possible leave the original ceiling in place, much less messy as well as preserving the original fabric, if you can live with / move the picture rail problem.

 

[AMc]

I had a similar problem with sloping sides bridged by a flat ceiling - a previous owner had "helpfully" removed all the plaster from the lath and with some reluctance we decided that as the walls were also bare and everything would need to be insulated we would replace the ceiling with modern materials. As we were also re-roofing we insulated between and over the rafters. Underneath we used insulated plasterboard on the walls but standard on the ceiling to avoid losing height.

FWIW I recently read an old Green Building Magazine article on the effects of air circulation behind insulation. In the situation we have the insulation runs all the way up to the ridge and the flat section of the ceiling is plain plasterboard. The article suggested to me that what actually happens is my precious heat goes up to the flat section where it moves on into the enclosed triangle above and cheerfully stays warm up there gradually losing heat into the world above.
If I had to do it again I would still run insulation to the ridge but I would lay wool (rock/sheep/recycled plastic) on the flat section. Access is restricted so I can't do that easily now or I would.

 

[Moo]

What an apposite thread this is - we're faced with a roof insulation problem, too.

The bedroom and bathroom in our back extension have (like the main part of the house) no insulation at all, and now that the weather's turning chilly both rooms are getting really uncomfortable. Insulating the front roof is no problem because there's a loft hatch, but we have no access to the extension roof and it seems rather an extravagance to pay for a hatch that will only be used once (there's not really any usable space in the roof in question).
So I'm interested in the idea of attaching some sort of insulation to the ceiling. Would it mean losing a great deal of head height?

 

[tobydog]

It must be that time of year where the temperature focuses the mind on all those insulation jobs we promised to do by September :roll: .

We have the same problem with our sloping ceilings upstairs where there is a 150mm void between the ceilings and the nasty felt under the thatch. This has been discussed via another thread with various suggestions on how to fill the void but still allow ventilation into the loft space. The house has a recent roof with the rafters and joists being bolted together. This creates an overlap which makes it almost impossible to slide any insulation batts down the void and get a decent fit between the timbers while still allowing air to flow over the top (think of the letter A where the horizontal line meets the slanty bits). I started filling the entire void and used the suggestion to force the felt apart at the overlap to let the air in. Unfortunately this didn't work because the felt is too tight and the overlap is excessive. I had already cut several areas of the felt instead to create vents which works but it was pointed out that leaving the felt intact increases the life of the thatch as it begins to fail and leak. I couldn't win.

In the end I stopped with only half the voids stuffed with insulation. I have a thatcher coming round on Saturday to address excessive moss of the north side and the badly fitting chimney lead flashing that is channelling water onto the thatch. I'll be getting some ideas from him. He is the guy who did the ridge 7 years ago.

 

[dalivar]

I'm pretty sure our plasterer said the insulated plaster board is about 4cm thick. I think that's what we'll do after all, the comment about the rafters being a cold bridge was the decider. I'm going to try and post a pic of the room. The picture rail is so close to the ceiling that it doesn't seem worth the inconvenience trying to save it.

 

[Penners]

we have no access to the extension roof and it seems rather an extravagance to pay for a hatch that will only be used once

In your shoes I think I would be investigating some of the free insulation deals around. I can't give you chapter and verse on who qualifies for what, but you as you can't get access to the place where the insulation needs to be laid, I wonder whether the approved supplier might create one as part of the (free) deal.

But even if you have to pay to create the hatch yourself, it should be a pretty straightforward job without too much cost attached. And if the insulation is then laid free, it seems like a worthwhile investment for all those fuel-saving years ahead.

This might be a useful place to start looking into the matter:

http://www.which.co.uk/energy/creating-an-energy-saving-home/guides/energy-grants/free-insulation-deals/

 

[Feltwell]

Moo - I echo Penner's comments, except that I'm not sure any insulation company would do the hatch for free.

However - fitting a loft hatch into an existing ceiling is an easy job for any carpenter/ general builder, and it will be much easier to insulate from above the existing ceiling if there is enough of a void to do so. I presume your extension has a sloping, tiled/slated roof? Insulating underneath your existing ceiling means screwing sheets of insulated plasterboard from beneath, and then getting a plasterer to skim over the sheets afterwards to make your new ceiling. Much less hassle to create a hatch!

I had to do more or less the same thing here - actually, I drilled through a cable that some previous owner had installed at 30 degrees off vertical :roll: and I had to get into the previously sealed off roof void to repair it. I cut a hole in the ceiling and made a hatch, and whilst I was up there I laid insulation.

 

[Feltwell]

I'm pretty sure our plasterer said the insulated plaster board is about 4cm thick. I think that's what we'll do after all, the comment about the rafters being a cold bridge was the decider. I'm going to try and post a pic of the room. The picture rail is so close to the ceiling that it doesn't seem worth the inconvenience trying to save it.

Insulated plasterboard comes in a variety of thicknesses. If you can live with the headroom loss then 100mm / 4" of insulation bonded to 1/2" of plasterboard will do a great job of making your room warmer. I also wouldn't fuss too much about the picture rail.

Seconds and Co are good for insulation deals - my insulated plasterboard came from them.

http://www.secondsandco.co.uk/

Fitting 8'x4' boards to a ceiling is hard work! You may well find your plasterer will do it for you if you don't fancy doing it yourself, for a price of course. There's nothing wrong with undercladding an existing ceiling to get more insulation in - breathability in old buildings doesn't really matter with ceilings.

 

[dalivar]

This is true, my other half fitted one in our bedroom since it also had no hatch. It would take someone more experienced about half a day i expect.

 

[jocelyn plummer]

Moo, I am inclined to agree with Penners advice, however, as you were at one time thinking of redoing the roof subject to the piggy bank, would it be an idea to have the extension roof sorted and insulate that bit at the same time? We have found that taking a short cut has been nothing but a source of irritation and annoyance, and wish that we had completed small, important projects properly a bit at a time. They always seem to need doing at some point when it is least convenient! Conversely, that 'small' step can lead to a whole lot of other unforeseen nasties!! That's the way it is with a period property!!!
How is the ceiling rose getting on?
xx

 

[Moo]

Wise words, Joss. I think we'll be sensible and go for the hatch option; there's a passage that runs past the bathroom to the bedroom, so it wouldn't be too noticeable there.
The ceiling rose stripping is finished, and it looks magnificent. But I've now turned my attention to the cornice, and that is turning out to be even more amazing! I've been taking photographs, of course, and will post before-and-after pictures as soon as I can be bothered with fiddling around with Flickr. If only one could just drag and drop!
xxx

 

[jocelyn plummer]

Brilliant! Cornice pics will be exciting! Loft hatch excellent idea. Something else I find a problem with this downsize lark, is, the rooms are smaller and one can see everything in one sweeep of the eye; flaws, ( or perceived flaws), tend to stand out, but I suspect that others do not see them!

 

[Moo]

I'm hoping that when the house eventually stops being an eyesore in its entirety, I'll be able to distract visitors with a few eyecatching objects.

 

[LadyArowana]

I'm hoping that when the house eventually stops being an eyesore in its entirety, I'll be able to distract visitors with a few eyecatching objects.

I can vouch for the fact that elephants are very effective at that.

 

[jocelyn plummer]

And a plate of kit-kats!

 

[worms]

And a plate of kit-kats!

I think you have just created the universal PPUK post, which could be posted at any point in any thread and be appropriate!

 

[Penners]

I'll second that, with one small addendum - the aforementioned Kit-Kats must be the four-finger model. None of yer namby-pamby two-finger jobs.

 

[worms]

I'll bow to the superior knowledge of our kit-kat guru on this (who on another thread has correctly identified my weakness of judging by price alone) but I am more than happy to eat two or more two-finger kit-kats to make up for any deficiency of digits per pack.

I must confess, though, that I find kit-kat shopping a most trying experience. In order to throw the price-conscious off the scent, 4-finger bars are in a different aisle from 2-finger bars, then they variously pack them in 8s, 9s, 14s, 16s, 24s and 48s, with the shelf note listing some as price per 100g and others as price per bar, then they subtly add offers, and multi-buy reductions...

Perhaps we need to establish our own PPUK Kit-Kat purchasing cartel!

 

[Penners]

Perhaps we need to establish our own PPUK Kit-Kat purchasing cartel!

Now, that is just about the best piece of PPUK advice that I've seen to date. If we elected a spokesperson to talk to Nestle's head office, we could perhaps negotiate our own containerload.