Best way to insulate a sloping ceiling.

[BlindPete]

We finally connected all the new cast iron radiators up yesterday. This means we can stop using the electric heaters. I did the btu calculations for each room, stating zero insulation, solid walled construction, window size and type etc. I went slightly higher than recommended with the btus.

The rads were on most of yesterday and last night and only took our bedroom from 12 degrees to 15.5. Each radiator is running between 58 and 60 degrees according to my black and decker infrared thermometer.

This ceiling won’t be helping.


Do any of you kind folk have any suggestions of have successfully insulated this type of ceiling please?

It’s 12.5mm plasterboard nailed to thin bearing timbers which are nailed to the roof timbers, then roof membrane and the stone slates. Not much of a void for air flown into the main roof area.
Another radiator would help I’m sure but any heat produced will just get sucked away.
Thanks kindly for any thoughts. Pete.

 

[Cubist]

Hi Pete, the apparent age of the exposed timbers in the ceiling suggests that those with the smallest cross-section are unlikely to be much more than 100mm/4inches on the side. If I'm right there would be very little room for any kind of insulation material that would not require the complete removal of the extant plasterboard and the bearers to which it is nailed. The bearers having to be removed to provide sufficient depth for any new pre-insulated boards whilst leaving sufficient room for airflow around the battens supporting the stone slates. My guess is that with those restrictions you may have to enclose the exposed rafters. Is that something you would contemplate for an extra couple of degrees?

 

[88v8]

We finally connected all the new cast iron radiators up yesterday. This means we can stop using the electric heaters. I did the btu calculations for each room, stating zero insulation, solid walled construction, window size and type etc. I went slightly higher than recommended with the btus.
The rads were on most of yesterday and last night and only took our bedroom from 12 degrees to 15.5. Each radiator is running between 58 and 60 degrees according to my black and decker infrared thermometer.

Well done for making calcs rather than just guessing.
Assume you have balanced the system.

Ideally the rads will be under the windows, so if two windows two smaller rads where possible, not always possible of course.

That looks like 15mm pipe... one can get 15,000 BTU through 15mm, so it's fine provided your total 15mm loop does not exceed 15,000 BTU and the total of 15mm pipe does not exceed 80ft, after that the pump pressure may become excessive.

What was your target temp for the bedroom? 65F? Here, we heat to 62F, but when we had ch in our previous house it would have been nearer 65F (18C).

The manufacturer's quoted rad output unless stated otherwise will be for a flow of 180F and a return of 160F (80C/70C) so if you are running the boiler colder you will have less output.

Unless you are prepared to lose sight of those nice old beams, as you say there is not much scope for insulation. Too easy to end up sacrificing a period interior on the altar of insulation.
Sorry no easy answer.

 

[CliffordPope]

I've never been too fussed about bedroom air temperatures. It's the insulation directly on the bed that counts.

 

[Cubist]

Looking at your photo again I would suggest you consider heavier and better fitting curtains as a first effort to improve heating efficiency in that room. Whilst the windows, judging by the handles, are likely double glazed, the heat loss through them may be much more than you think. In many of the first floor rooms here I fitted internal shutters - largely because the windows were either very small or installed in walls that slope significantly - thus rendering curtains entirely pointless. These have proven highly efficient in every regard.

 

[BlindPete]

Looking at your photo again I would suggest you consider heavier and better fitting curtains as a first effort to improve heating efficiency in that room. Whilst the windows, judging by the handles, are likely double glazed, the heat loss through them may be much more than you think. In many of the first floor rooms here I fitted internal shutters - largely because the windows were either very small or installed in walls that slope significantly - thus rendering curtains entirely pointless. These have proven highly efficient in every regard.

Thanks to everyone for their thoughts and advice. The house seemed to warm up a little yesterday but was still cold.

The Tado thermostat was in our bedroom and set to 19degrees Celsius. It reached this yesterday but maybe it was helped with solar gains as the front wall in the picture is south facing. The surface temperature of the all radiators are between 58 and 62 degrees Celsius according to the thermal gun thing I have.

We are going to concentrate on draft stopping as much as we can and will definitely be getting some thick heavy curtains which will suit the window reveals better.

We positioned the radiator in the middle of the two windows as we thought we’d only need one radiator. We can hopefully add some additional columns to this one or get second radiator to help warm the space if needed.

I couldn’t imagine covering the beautiful old timbers and would love to replace the upvc windows with something more in keeping. My neighbour has a joiners shop and made some Yorkshire sliding sash windows using accoya timber for his home. They look stunning and show zero signs of wear.

 

[steveb]

also remember that a solid walled house, you need to heat the mass of the walls up as well - so heating from cold is going to take a loooong time as the walls need to come up to temperature. But once they are warmed up, they act as a large heat buffer.

I have seen a recommendation that you set the temperature constantly to a low level (15 degrees) and keep it there - or at least don't turn it below or off overnight, to prevent cycling of hot and cold which can exaggerate conditions for damp.

 

[Cubist]

also remember that a solid walled house, you need to heat the mass of the walls up as well - so heating from cold is going to take a loooong time as the walls need to come up to temperature. But once they are warmed up, they act as a large heat buffer.

I have seen a recommendation that you set the temperature constantly to a low level (15 degrees) and keep it there - or at least don't turn it below or off overnight, to prevent cycling of hot and cold which can exaggerate conditions for damp.

And fully agreed. We use our wood-fired central heating to maintain a mean of around 15-16 and our small wood-burner for 'point' heating in the main living area to kick the temperature up when wanted/needed.

 

[Roger440]

Thanks to everyone for their thoughts and advice. The house seemed to warm up a little yesterday but was still cold.

The Tado thermostat was in our bedroom and set to 19degrees Celsius. It reached this yesterday but maybe it was helped with solar gains as the front wall in the picture is south facing. The surface temperature of the all radiators are between 58 and 62 degrees Celsius according to the thermal gun thing I have.

We are going to concentrate on draft stopping as much as we can and will definitely be getting some thick heavy curtains which will suit the window reveals better.

We positioned the radiator in the middle of the two windows as we thought we’d only need one radiator. We can hopefully add some additional columns to this one or get second radiator to help warm the space if needed.

I couldn’t imagine covering the beautiful old timbers and would love to replace the upvc windows with something more in keeping. My neighbour has a joiners shop and made some Yorkshire sliding sash windows using accoya timber for his home. They look stunning and show zero signs of wear.

Stopping draughts will be your number one gain. They will orobably be everywhere. If you really want to do it well, get a car radiator fan on a board with a car battery, stick it over the doorway and turn it on. You will be surprised how many you will find.

 

[steveb]

We had this done on a new build. The chap doing the test said that it's easier to find leaks when the fan is sucking air from the building, and you can then walk around with a wet hand and feel the outside air where it comes in.

 

[ShaneB]

I have a question on a simular sloping ceiling ( Thatched roof) although more concerned that I could trap damp in that area and what it should be boarded and plastered with?

Oh and we heat to 22C cycle to 21C for a couple of hours morning and afternoon, and set to 16C at night for a few hours and if we are away 16C previously much less while we were away but didn’t like that much when we returned.
Wife still says it’s cold.

 

[Cubist]

I have a question on a simular sloping ceiling ( Thatched roof) although more concerned that I could trap damp in that area and what it should be boarded and plastered with?

Oh and we heat to 22C cycle to 21C for a couple of hours morning and afternoon, and set to 16C at night for a few hours and if we are away 16C previously much less while we were away but didn’t like that much when we returned.
Wife still says it’s cold.

22C!

Sorry, but my only insulation suggestion concerns your Xmas/Birthday/Anniversary gift list - jumpers, woolly socks, thermal vests, onesies, etc.

 

[malcolm]

@ShaneB Worth photos of what you are starting with. Maybe in a new thread. A thatched roof should have quite a good U value already. It's fairly close to what building regs like to see even in modern times.

Worth buying an infrared thermometer (they are really cheap) and pointing it at the walls and ceiling to see where the cold bits are.