Partial loft conversion - insulation issues

Brebal

That’s really informative, thanks. I’ll do some research on the boards. 

Not sure when the house was built, prob more than 50 years ago. I don’t know what’s under the carpets downstairs, the floorboards upstairs have been getting increasingly creaky lately tho!

I have found one draught that comes in under my bedroom door. Can’t feel it in the other rooms upstairs, in or out, and can’t feel it anywhere else or work out where it’s coming from. All windows and doors are draught free. I’ll check the skirting boards. 👍

Doozergirl

Bendy_House said:

Brebal, this lined loft area has ladder access? Via a hatch? That's normally closed? Cool. I'd forget doing anything to any of that.

The simplest - and most effective by far - method of insulating your ceiling, especially as it's sloping, is to line it on the underside using insulated plasterboard. Even 1" thick insulation will be very effective. 2" will be better, if you can afford to lose the headroom. 1.5" is a compromise.

Bearing in mind that the current regulation depth is 12.5cm - over 5 inches.   That little isn't going to do an awful lot for a roof.    If you're doing it, do it properly.  

Neil49

Are your cavity walls insulated, in fact do you have cavity walls?
I used to own a house built in the early 70s and quite honestly the standard of construction and insulation was poor. The house was full of draughts and leaked heat from all over the place.
I moved to a new build in 2007 and the difference in the standard of insulation was amazing. 

Bendy_House

Doozergirl said:

Bendy_House said:

Brebal, this lined loft area has ladder access? Via a hatch? That's normally closed? Cool. I'd forget doing anything to any of that.

The simplest - and most effective by far - method of insulating your ceiling, especially as it's sloping, is to line it on the underside using insulated plasterboard. Even 1" thick insulation will be very effective. 2" will be better, if you can afford to lose the headroom. 1.5" is a compromise.

Bearing in mind that the current regulation depth is 12.5cm - over 5 inches.   That little isn't going to do an awful lot for a roof.    If you're doing it, do it properly.  

It might not do a lot towards current regs, but it'll do a HELL of a lot towards insulating that ceiling. And it's the cheapest and simplest solution, which carries no side-effect risks.

I might as well repeat my own experience as an example; single-skinned garage, insulated with just 1" battens with 1" Jablite in between, and 35mm insulated board (so 25mm actual insulation) on top. That room is the easiest to heat in the house by a country mile. The heat from the plasma TV I use as a monitor ~200W? - is enough.

(Another reason why that room is easy to heat compared to the rest of my 1930'shouse is that the floor is solid = no draughts. What insulation did I put under there? 2" of Jablite)

I 'could' bring that room up to current regs, but it would cost £ks, wreck the place in the process, make it too narrow, and I wouldn't even NOTICE the improvement; insulation is a process of diminishing returns! 

The OP has stated that they don't want to rip up the floors, causing £ks of damage, to tackle this. And any other midway solution - stuffing insulation down the eaves will, I can almost guarantee, fail to be effective (I have tried - slip down 'rigid' type, and you'll be limited in thickness AND there will be air leaks. Try and get 'loft' insulation down there will be even less effective, and will likely partially block the essential ventilation). 

I totally get what you are saying, and I think improved insulation standards are an essential move, but are only cost-effective for new builds, actual renovations, or if heavily subsidised. For the OP to start ripping things apart to the tune of £ks just to add ceiling insulation is nuts, especially if one or two inches of PUR will get then 90% of the way for just £undreds.

Bendy_House

Brebal said:

That’s really informative, thanks. I’ll do some research on the boards. 

Not sure when the house was built, prob more than 50 years ago. I don’t know what’s under the carpets downstairs, the floorboards upstairs have been getting increasingly creaky lately tho!

I have found one draught that comes in under my bedroom door. Can’t feel it in the other rooms upstairs, in or out, and can’t feel it anywhere else or work out where it’s coming from. All windows and doors are draught free. I’ll check the skirting boards. 👍

Draughts in older houses is a big issue. My 1930s house is a prime example, but I was unaware of its significance when I moved in and had the chance to sort it. 

With the downstairs bedroom doors closed, I can feel a steady and significant draught come out from under the doors into the corridor. This usually makes its way into the sitting room, where the draw is the open fireplace. The bedrooms are hard to heat. They have reg- level loft insulation (well, from 8 years ago), recent dg windows, and cavity wall insul. The only significant issue is the percolating of wind through the T&G floorboards.

We need to have new carpets at some point, so my plan is to seal the skirting board gaps (the worst culprit) and stick down 8mm LD fibreboard sheets (as used with some laminate floors), also sealing between them for draught-proofing. I'm anticipating that this will SIGNIFICANTLY improve matters, and be immediately noticeable.

It'll cost - ooh - a couple of £undred max, and be done in a couple of hours. Should I take up the floor, cut insulation to fit TIGHTLY in between the joists, or drape netting across them to support 'loft' insulation instead? You have got to be crazy. That would be hugely disruptive, take at least a day of solid work, cost - I dunno, it depends on how many boards I wreck, and be HOW much more effective? I suspect not to a measurable degree. AND my cheap method will guarantee zero draughts - the ' proper' way won't (unless they ALSO do the sealing...)

Doozergirl

Bendy_House said:

Doozergirl said:

Bendy_House said:

Brebal, this lined loft area has ladder access? Via a hatch? That's normally closed? Cool. I'd forget doing anything to any of that.

The simplest - and most effective by far - method of insulating your ceiling, especially as it's sloping, is to line it on the underside using insulated plasterboard. Even 1" thick insulation will be very effective. 2" will be better, if you can afford to lose the headroom. 1.5" is a compromise.

Bearing in mind that the current regulation depth is 12.5cm - over 5 inches.   That little isn't going to do an awful lot for a roof.    If you're doing it, do it properly.  

It might not do a lot towards current regs, but it'll do a HELL of a lot towards insulating that ceiling. And it's the cheapest and simplest solution, which carries no side-effect risks.

I might as well repeat my own experience as an example; single-skinned garage, insulated with just 1" battens with 1" Jablite in between, and 35mm insulated board (so 25mm actual insulation) on top. That room is the easiest to heat in the house by a country mile. The heat from the plasma TV I use as a monitor ~200W? - is enough.

(Another reason why that room is easy to heat compared to the rest of my 1930'shouse is that the floor is solid = no draughts. What insulation did I put under there? 2" of Jablite)

I 'could' bring that room up to current regs, but it would cost £ks, wreck the place in the process, make it too narrow, and I wouldn't even NOTICE the improvement; insulation is a process of diminishing returns! 

The OP has stated that they don't want to rip up the floors, causing £ks of damage, to tackle this. And any other midway solution - stuffing insulation down the eaves will, I can almost guarantee, fail to be effective (I have tried - slip down 'rigid' type, and you'll be limited in thickness AND there will be air leaks. Try and get 'loft' insulation down there will be even less effective, and will likely partially block the essential ventilation). 

I totally get what you are saying, and I think improved insulation standards are an essential move, but are only cost-effective for new builds, actual renovations, or if heavily subsidised. For the OP to start ripping things apart to the tune of £ks just to add ceiling insulation is nuts, especially if one or two inches of PUR will get then 90% of the way for just £undreds.

It's nice for the OP to understand what is actually required as a minimum standard in this country though, don't you think? 

 

Inch for inch, Jablite's u value is nowhere near that of a celotex type board.   It's cheaper for a reason. 

50mm Celotex itself is twice as insulating as 25mm, and twice again between 50mm and 100mm.  Diminishing returns are seen at greater thicknesses than have previously been used in the average house.  

Even then, when your bills are three times higher than they were last winter, the savings start to add up more quickly than they did.  

Chickereeeee

Bendy_House said:

We need to have new carpets at some point, so my plan is to seal the skirting board gaps (the worst culprit) and stick down 8mm LD fibreboard sheets (as used with some laminate floors), also sealing between them for draught-proofing. I'm anticipating that this will SIGNIFICANTLY improve matters, and be immediately noticeable.

It'll cost - ooh - a couple of £undred max, and be done in a couple of hours. Should I take up the floor, cut insulation to fit TIGHTLY in between the joists, or drape netting across them to support 'loft' insulation instead? You have got to be crazy. That would be hugely disruptive, take at least a day of solid work, cost - I dunno, it depends on how many boards I wreck, and be HOW much more effective? I suspect not to a measurable degree. AND my cheap method will guarantee zero draughts - the ' proper' way won't (unless they ALSO do the sealing...)

No need to do all that. We moved into a house that HAD the fibre board over the floorboards. It was really cold at foot-level, due to draughts from beneath the skirting boards. I had the fibre board ripped out  - partly because I wanted to insulate the central heating pipes under the floor. I sealed the gaps under the skirting boards, and any floorboard gaps close to the walls. Then, a simple paper layer underneath a good wool underlay provided all the draught proofing and insulation required, before laying the carpet. It made a HUGE difference. And I can still get under the floors if needed.

Bendy_House

Doozergirl said:

Bendy_House said:

Doozergirl said:

Bendy_House said:

Brebal, this lined loft area has ladder access? Via a hatch? That's normally closed? Cool. I'd forget doing anything to any of that.

The simplest - and most effective by far - method of insulating your ceiling, especially as it's sloping, is to line it on the underside using insulated plasterboard. Even 1" thick insulation will be very effective. 2" will be better, if you can afford to lose the headroom. 1.5" is a compromise.

Bearing in mind that the current regulation depth is 12.5cm - over 5 inches.   That little isn't going to do an awful lot for a roof.    If you're doing it, do it properly.  

It might not do a lot towards current regs, but it'll do a HELL of a lot towards insulating that ceiling. And it's the cheapest and simplest solution, which carries no side-effect risks.

I might as well repeat my own experience as an example; single-skinned garage, insulated with just 1" battens with 1" Jablite in between, and 35mm insulated board (so 25mm actual insulation) on top. That room is the easiest to heat in the house by a country mile. The heat from the plasma TV I use as a monitor ~200W? - is enough.

(Another reason why that room is easy to heat compared to the rest of my 1930'shouse is that the floor is solid = no draughts. What insulation did I put under there? 2" of Jablite)

I 'could' bring that room up to current regs, but it would cost £ks, wreck the place in the process, make it too narrow, and I wouldn't even NOTICE the improvement; insulation is a process of diminishing returns! 

The OP has stated that they don't want to rip up the floors, causing £ks of damage, to tackle this. And any other midway solution - stuffing insulation down the eaves will, I can almost guarantee, fail to be effective (I have tried - slip down 'rigid' type, and you'll be limited in thickness AND there will be air leaks. Try and get 'loft' insulation down there will be even less effective, and will likely partially block the essential ventilation). 

I totally get what you are saying, and I think improved insulation standards are an essential move, but are only cost-effective for new builds, actual renovations, or if heavily subsidised. For the OP to start ripping things apart to the tune of £ks just to add ceiling insulation is nuts, especially if one or two inches of PUR will get then 90% of the way for just £undreds.

It's nice for the OP to understand what is actually required as a minimum standard in this country though, don't you think? 

 

Inch for inch, Jablite's u value is nowhere near that of a celotex type board.   It's cheaper for a reason. 

50mm Celotex itself is twice as insulating as 25mm, and twice again between 50mm and 100mm.  Diminishing returns are seen at greater thicknesses than have previously been used in the average house.  

Even then, when your bills are three times higher than they were last winter, the savings start to add up more quickly than they did.  

Of course.

And my mention of Jablite was to EMPHASISE the improvement made to my room when using such a relatively poor quality product.

50MM Celotex may have double the 'U' value of 25, but that does not mean it's twice as effective; it does not keep in twice the heat.

I don't have, and am not too concerned with finding, actual figures. I think it's suffice to make a statement of the obvious;  IF, say, 25mm of Celotex cuts down heat transfer through an uninsulated wall by, say, a factor of 10 - and, depending on what that wall is made of, I bet it does - then adding a further 25mm layer will only bring that level up by 'one', ie a total factor of 11. That is because the first 25mm will have reduced the heat transfer to its outside surface by a tenth to begin with. And a further tenth of a tenth is only 1.

All I am saying is, if anyone is carrying out major renovation work, then YES, of course, insulate to current regs. But, if you are not, but still want a SIGNIFICANT improvement at the lowest cost and disruption, then internally insulating with PUR or PIR is, imo, the way to go. It might not be to current regs, but it'll be TRANSFORMATIVE. 

What's more, there is every chance you will actually recoup your outlay during your time in the house.

If you pay to rip up floors or ceilings to fit insulation to current regs, or - worse still - fit external insulation, then well done you, but you will be seriously out of pocket. (Unless you get a ~90% grant).

Doozergirl

Bendy_House said:

Doozergirl said:

Bendy_House said:

Doozergirl said:

Bendy_House said:

Brebal, this lined loft area has ladder access? Via a hatch? That's normally closed? Cool. I'd forget doing anything to any of that.

The simplest - and most effective by far - method of insulating your ceiling, especially as it's sloping, is to line it on the underside using insulated plasterboard. Even 1" thick insulation will be very effective. 2" will be better, if you can afford to lose the headroom. 1.5" is a compromise.

Bearing in mind that the current regulation depth is 12.5cm - over 5 inches.   That little isn't going to do an awful lot for a roof.    If you're doing it, do it properly.  

It might not do a lot towards current regs, but it'll do a HELL of a lot towards insulating that ceiling. And it's the cheapest and simplest solution, which carries no side-effect risks.

I might as well repeat my own experience as an example; single-skinned garage, insulated with just 1" battens with 1" Jablite in between, and 35mm insulated board (so 25mm actual insulation) on top. That room is the easiest to heat in the house by a country mile. The heat from the plasma TV I use as a monitor ~200W? - is enough.

(Another reason why that room is easy to heat compared to the rest of my 1930'shouse is that the floor is solid = no draughts. What insulation did I put under there? 2" of Jablite)

I 'could' bring that room up to current regs, but it would cost £ks, wreck the place in the process, make it too narrow, and I wouldn't even NOTICE the improvement; insulation is a process of diminishing returns! 

The OP has stated that they don't want to rip up the floors, causing £ks of damage, to tackle this. And any other midway solution - stuffing insulation down the eaves will, I can almost guarantee, fail to be effective (I have tried - slip down 'rigid' type, and you'll be limited in thickness AND there will be air leaks. Try and get 'loft' insulation down there will be even less effective, and will likely partially block the essential ventilation). 

I totally get what you are saying, and I think improved insulation standards are an essential move, but are only cost-effective for new builds, actual renovations, or if heavily subsidised. For the OP to start ripping things apart to the tune of £ks just to add ceiling insulation is nuts, especially if one or two inches of PUR will get then 90% of the way for just £undreds.

It's nice for the OP to understand what is actually required as a minimum standard in this country though, don't you think? 

 

Inch for inch, Jablite's u value is nowhere near that of a celotex type board.   It's cheaper for a reason. 

50mm Celotex itself is twice as insulating as 25mm, and twice again between 50mm and 100mm.  Diminishing returns are seen at greater thicknesses than have previously been used in the average house.  

Even then, when your bills are three times higher than they were last winter, the savings start to add up more quickly than they did.  

Of course.

And my mention of Jablite was to EMPHASISE the improvement made to my room when using such a relatively poor quality product.

50MM Celotex may have double the 'U' value of 25, but that does not mean it's twice as effective; it does not keep in twice the heat.

I don't have, and am not too concerned with finding, actual figures. I think it's suffice to make a statement of the obvious;  IF, say, 25mm of Celotex cuts down heat transfer through an uninsulated wall by, say, a factor of 10 - and, depending on what that wall is made of, I bet it does - then adding a further 25mm layer will only bring that level up by 'one', ie a total factor of 11. That is because the first 25mm will have reduced the heat transfer to its outside surface by a tenth to begin with. And a further tenth of a tenth is only 1.

All I am saying is, if anyone is carrying out major renovation work, then YES, of course, insulate to current regs. But, if you are not, but still want a SIGNIFICANT improvement at the lowest cost and disruption, then internally insulating with PUR or PIR is, imo, the way to go. It might not be to current regs, but it'll be TRANSFORMATIVE. 

What's more, there is every chance you will actually recoup your outlay during your time in the house.

If you pay to rip up floors or ceilings to fit insulation to current regs, or - worse still - fit external insulation, then well done you, but you will be seriously out of pocket. (Unless you get a ~90% grant).

You can't be bothered to do the maths but you can shout  (suggesting some type of aggressive authority) and tell people what a decent payback is on investment?  

If the OP wants to do it as cheaply as possible with instant payback, it's what I said. At least 300mm  Rockwool over the joists, even over the existing floor, as long as it's up to the external walls creating some kind of thermal envelope.  

A roof has no walls and is purposely ventilated under the tiles.  In terms of heat loss, it is the singularly most vulnerable part of a house.  The quality and depth of insulation makes far more difference there than in any other part of a house.

Bendy_House

Wow, Doozer :-(

(That wasn't 'shouting', by the way - I was on my phone, and don't have access to 'italics' and other subtleties in order to emphasise points as I usually do).

1) How will the OP get any useful amount of insulation down the sloping eaves?

2) How much will it cost the OP to have this loft's floor taken up for that 300mm+ of loft insulation?

3) And how does 300mm of loft insulation compare with PUR?