Please help me improve my home insulation.

Paulrsm · 1 Jan 2014

Hi I’m hoping I can get some advice on how to improve my insulation situation.
My house is a timber frame kit house approx 25 years old. It is ‘dormer’ type with the upstairs being within the roof. It is a large 6 bed house and difficult to heat.

I have several issues that I need to deal with.

1. Gap between upstairs floor and downstairs ceiling. Where this opens into the loft space behind the knee walls there is no sealing at all.
2. Insulation between internal garage ceiling and upstairs bedroom floor. None exists.
3. Insulation within loft space on top of downstairs ceiling. Currently some insulation there, beams are 200mm deep.
4. Insulation on loft side of kneewalls. Beams are 120mm deep, most have fibreglass rolls pushed inbetween beams.
5. Insulation on pitched part of roof. This gap is 6inch and it has 2inch polystyrene sheets in, laid on the plasterboard with 4inch gap to roof wood panel. Also noticed that some electric cables layed on these sheets have sunk into them.

I have listed these in the order that I think I need to prioritise them (would you agree?). The ‘upper’ loft is well insulated because a firm came in and did it for free last year. The loft spaces are very well ventilated with grills in the soffits.

I have tried researching these issues and have made some headway but will admit some confusion. Mainly to do with condensation issues and when vapour barriers are/aren’t needed.

So, realising this is going to be an epic post (sorry), point 1 first:
If I am right I need to ‘air seal’ all the openings into the loft space from between the downstairs ceiling and upstairs floor. These openings are roughly 350mm by 200mm and I have worked out there are about 106 of these openings.
How best, and cost effective, to do this? I was thinking insulation board and sealing the gaps with expanding foam? How thick insulation board? There’s a guy in the village selling celotex 140mm boards for £45 but I imagine these would be an expensive overkill. Would this board need a vapour barrier? Which side?

If it’s ok I’ll work through the other issues one at a time when I’m happy with what my plans are.

Thanks and Happy New Year.
Paul

Perry525 · 1 Jan 2014

Your priority is draft proofing;

Keep in mind that the wind forms an area of low pressure to the lee, and above a building, and the air will mainly be sucked out of that side.

The wind is pulling your warm air mostly from higher holes, and that warm air is being replaced by cold pulled in through lower holes, air that you are having to warm.

Draft proof the room you use most, followed by the bathroom and your bedroom.

Block all the holes at the bottom first, these will be easier to identify as you can feel cold air coming in, and if you use a candle, the flame will bend in the draft, it doesn't matter with what, just fill them keep the cold air out.

Then do the higher holes. Once all the holes are blocked, the home will feel a lot warmer.

Then insulate starting with the room you use most, the bathroom and your bedroom.

Note: You cannot be sure that professionally installed insulation has been done correctly! Very often, they leave gaps in places that are hard to reach, or where they think it unlikely that owners will check, you really must look and make sure there are no gaps or cracks for your expensive heat to escape through.

Fiberglass is useless as an insulation, except when it is in a sealed plastic bag, or airtight compartment.

The best insulation is a Vacuum Flask, unfortunately they don't come in either room sizes or shapes. The next best is Aerogel, this is wildly expensive. For practical long term purposes a closed cell sheet insulation like polystyrene is best. The proprietary insulation's are for the first 20 years better, but in time the inert gases disappear and they are as good as polystyrene, if you want more insulation go for thicker polystyrene.

I don't know what you can afford, but if you have plasterboard ceilings, then cutting polystyrene to a tight push fit (it is soft and compressible)
and filling the spaces between the joists, will give a good result. Filling any odd gaps with canned spray foam will help.

Polystyrene can strip the plasticiser from electric cable. Placing paper or something else under the cables will prevent this.

As I wrote earlier, the wind pulls the heat from your home. Having a ventilated loft is wrong, as the wind pulls the warm air from your home. Seal all holes. If water vapour gets into the loft, it will find its way out into the sky.

Water vapour is produced in the home by, cooking, washing, drying, flowers, animals, plants, people. It is programmed by nature to head for the nearest cold surface to condense, usually a window, it can easily pass through plasterboard without making it wet. To disappear into the loft and then the sky.It can be controlled by opening a window to let it out. The air outside is usually colder and drier. I can be collected by a dehumidifier, or blown outside using a kitchen or bathroom extractor fan. In the bathroom a fan with heat recovery is best, it will do away with draft, and save perhaps 80% of your heat. In the kitchen open the window when using the fan.

tony1851 · 1 Jan 2014

Never mind draft-proofing and the rest.
Your first priority is to replace the lighting cables which are currently lying on top of the polystyrene - that's an immediate safety problem.
(unless I've misunderstood?).

tony1851 · 1 Jan 2014

Perry525 said:
The proprietary insulation's are for the first 20 years better, but in time the inert gases disappear and they are as good as polystyrene, if you want more insulation go for thicker polystyrene.

Polystyrene has a lambda-value of nearly twice that of the PIR/PUR boards. Granted the latter loose a little over time due to gas migration, it's nothing like one-half in 20 years.

Bankrupt · 1 Jan 2014

Perry525 said:
A closed cell sheet insulation like polystyrene is best. if you have plasterboard ceilings, then cutting polystyrene to a tight push fit (it is soft and compressible)
and filling the spaces between the joists, will give a good result.

Polystyrene should NOT be used for insulation in the manner suggested by Perry525. To do so creates a serious fire hazard and contravenes building regulations.......

Like other organic compounds, polystyrene is highly flammable. Polystyrene is classified according to DIN4102 as a "B3" product, meaning highly flammable or "Easily Ignited." When ignited it creates highly toxic fumes. As a consequence, although it is an efficient insulator at low temperatures, its use is prohibited in any exposed installations in building construction. It must be concealed behind drywall, sheet metal, or concrete.

http://www.pacspackaging.co.uk/DATASHEETS/Expanded Polystyrene COSHH.pdf

Paulrsm · 2 Jan 2014

Thanks for the replies.

Draught wise I think the downstairs is fairly ok. Being a farly new kit house it's not falling to bits and we had new windows and doors fitted a couple of years back. The only thing I'd like to do down stairs is insulate under the floorboards, but as I'm really not looking forward to that one I left it off my original list.

Yes I understand the cabling is dangerous and am sourcing some lengths of conduit to run new cables through the pitched roof through.

So back to my original insulation situation I have just sourced some sheets of celotex 140mm which I plan on cutting into 'bricks' to fill the openings described in No 1 above. I will seal these in with expanding foam. I was thinking of cutting these 'bricks' to make them thinner 70mm rather than 140mm as I think 140mm is overkill for this purpose yes/no?
The sheets have foil on both sides so when cut only one side will be foiled. For the purpose described in No1 above does it matter which side the foil is on. I was planning on leaving the foil visable when shoved between the ceiling and floor.

JohnD · 2 Jan 2014

Perry525 said:
Fiberglass is useless as an insulation, except when it is in a sealed plastic bag, or airtight compartment.

rubbish.

Perry525 said:
Having a ventilated loft is wrong, as the wind pulls the warm air from your home.

rubbish

Perry525 said:
The proprietary insulation's are for the first 20 years better, but in time the inert gases disappear and they are as good as polystyrene, if you want more insulation go for thicker polystyrene.

rubbish

Perry525 said:
In the kitchen open the window when using the fan.

rubbish

Perry525 · 2 Jan 2014

Bankrupt said:
Perry525 said:

A closed cell sheet insulation like polystyrene is best. if you have plasterboard ceilings, then cutting polystyrene to a tight push fit (it is soft and compressible)
and filling the spaces between the joists, will give a good result.

Click to expand...

Polystyrene should NOT be used for insulation in the manner suggested by Perry525. To do so creates a serious fire hazard and contravenes building regulations.......

Like other organic compounds, polystyrene is highly flammable. Polystyrene is classified according to DIN4102 as a "B3" product, meaning highly flammable or "Easily Ignited." When ignited it creates highly toxic fumes. As a consequence, although it is an efficient insulator at low temperatures, its use is prohibited in any exposed installations in building construction. It must be concealed behind drywall, sheet metal, or concrete.

http://www.pacspackaging.co.uk/DATASHEETS/Expanded Polystyrene COSHH.pdf[/QUOTE]

Polystyrene degrades in sunlight or at a temperature above 74C.
It melts at 240C. It is inflammable and is often glued to sheet plasterboard, which provides fire protection and a hard surface suitable for a skim coat plaster. Plasterboard provides a 30 minute fire wall.

Perry525 · 2 Jan 2014

The foil covering is there to keep the inert gas in, that provides an improved level of insulation for roughly 15 years, then it gradually disappears, and reverts to type.

geraldthehamster · 2 Jan 2014

Paulrsm said:
I have several issues that I need to deal with.

1. Gap between upstairs floor and downstairs ceiling. Where this opens into the loft space behind the knee walls there is no sealing at all.
2. Insulation between internal garage ceiling and upstairs bedroom floor. None exists.
3. Insulation within loft space on top of downstairs ceiling. Currently some insulation there, beams are 200mm deep.
4. Insulation on loft side of kneewalls. Beams are 120mm deep, most have fibreglass rolls pushed inbetween beams.
5. Insulation on pitched part of roof. This gap is 6inch and it has 2inch polystyrene sheets in, laid on the plasterboard with 4inch gap to roof wood panel. Also noticed that some electric cables layed on these sheets have sunk into them.

1. See 3. below.
2. Lift bedroom floor and insulate underneath with rockwool. Fibreglass is fine but is nastier to use than rockwool, unless encapsulated in plastic.
3. If you fill with rockwool between the joists in the loft space (do you mean in the eaves?), then if I've understood correctly this could also deal with your issue at 1., if you make sure it fills the gap where the floor starts.
Nothing wrong with your Celotex brick plan but I don't think it's necessary. That's if I've visualised this correctly.
4. Existing is probably effective; you could increase the depth if possible. It would be useful to have a vapour barrier, so consider replacing with foiled Celotex if you can get in there to do the job.
5. Are you planning on pulling off the plasterboard to redo this? If so, current regs (at least, in 2008 when I did something very similar) would indicate 4 inches of Celotex between the rafters, and another inch over the top, foiled to provide a vapour barrier. This will be toasty warm.

Do remove all polystyrene, as has been said.
Do ensure that all spaces on the cold side of any insulation are adequately ventilated - this applies to the space behind your knee walls, the space behind the insulation on the slopy part of the roof, and any loft space that you have above the bedroom ceiling. Air needs to flow - think soffit vents and ridge vents.

Also consider that while Celotex provides better thermal insulation, rockwool provides better sound insulation, especially the acoustic batts.

Disclaimer - I'm not a builder, but have done a complete refurb on my dormer bungalow, including insulation to building regs.

Cheers
Richard

geraldthehamster · 2 Jan 2014

JohnD said:
rubbish

I agree, I would disregard that post, though I'm sure it was helpfully offered.

Cheers
Richard

wrightwoodwork · 2 Jan 2014

The vapour barrier is fitted to all external walls that have insulation it can be in the form of foiled back plasterboard or visqueen vapour barrier. It is not fitted to the ceilings. The combs in the Dormer rooms gets a vapour barrier. Insulation in a loft in scotland is to be 300mm 1st layer going between and a second layer going across at right angles. It should come on to the internal wall head or in your situation on the insulation in between the rafter at the combs. There should be 50mm gap between the insulation and the sarking boards. The insulation goes under cables over pipes. Do not block off ventilation to the roof space or you will be contravening scottish building regs. In your garage area the ceiling should be insulted how you do it depends on how much you want to take like lifting floors or removing the ceiling which is a bit extreme and unnessary you could do a false insulated ceiling depending on how much room it should achieve a u value 0.18w/m2 K

Bankrupt · 2 Jan 2014

Perry525 said:
Bankrupt said:

Perry525 said:

A closed cell sheet insulation like polystyrene is best. if you have plasterboard ceilings, then cutting polystyrene to a tight push fit (it is soft and compressible)
and filling the spaces between the joists, will give a good result.

Click to expand...

Polystyrene should NOT be used for insulation in the manner suggested by Perry525. To do so creates a serious fire hazard and contravenes building regulations.......

Like other organic compounds, polystyrene is highly flammable. Polystyrene is classified according to DIN4102 as a "B3" product, meaning highly flammable or "Easily Ignited." When ignited it creates highly toxic fumes. As a consequence, although it is an efficient insulator at low temperatures, its use is prohibited in any exposed installations in building construction. It must be concealed behind drywall, sheet metal, or concrete.

http://www.pacspackaging.co.uk/DATASHEETS/Expanded Polystyrene COSHH.pdf[/QUOTE]

Polystyrene degrades in sunlight or at a temperature above 74C.
It melts at 240C. It is inflammable and is often glued to sheet plasterboard, which provides fire protection and a hard surface suitable for a skim coat plaster. Plasterboard provides a 30 minute fire wall.

Click to expand...

I am fully aware of the properties of polystyrene.

I REPEAT :

Using polystyrene in the manner you suggest (using it to fill the space between joists) leaves the polystyrene exposed on the attic side. That is therefore an exposed installation which constitutes a SERIOUS FIRE HAZARD and is specifically PROHIBITED by building regulations.

Polystyrene should also not be used anywhere near electrical cables. Plasticiser migration degrades the PVC insulation. The risk, in extreme cases, is that the cable insulation and sheathing material becomes very brittle and may fracture under very slight movement.
This of course would expose live conductors with consequent risk of fire.

Paulrsm · 3 Jan 2014

geraldthehamster said:
Paulrsm said:

I have several issues that I need to deal with.

1. Gap between upstairs floor and downstairs ceiling. Where this opens into the loft space behind the knee walls there is no sealing at all.
2. Insulation between internal garage ceiling and upstairs bedroom floor. None exists.
3. Insulation within loft space on top of downstairs ceiling. Currently some insulation there, beams are 200mm deep.
4. Insulation on loft side of kneewalls. Beams are 120mm deep, most have fibreglass rolls pushed inbetween beams.
5. Insulation on pitched part of roof. This gap is 6inch and it has 2inch polystyrene sheets in, laid on the plasterboard with 4inch gap to roof wood panel. Also noticed that some electric cables layed on these sheets have sunk into them.

Click to expand...

1. See 3. below.
2. Lift bedroom floor and insulate underneath with rockwool. Fibreglass is fine but is nastier to use than rockwool, unless encapsulated in plastic.
3. If you fill with rockwool between the joists in the loft space (do you mean in the eaves?), then if I've understood correctly this could also deal with your issue at 1., if you make sure it fills the gap where the floor starts.
Nothing wrong with your Celotex brick plan but I don't think it's necessary. That's if I've visualised this correctly.
4. Existing is probably effective; you could increase the depth if possible. It would be useful to have a vapour barrier, so consider replacing with foiled Celotex if you can get in there to do the job.
5. Are you planning on pulling off the plasterboard to redo this? If so, current regs (at least, in 2008 when I did something very similar) would indicate 4 inches of Celotex between the rafters, and another inch over the top, foiled to provide a vapour barrier. This will be toasty warm.

Do remove all polystyrene, as has been said.
Do ensure that all spaces on the cold side of any insulation are adequately ventilated - this applies to the space behind your knee walls, the space behind the insulation on the slopy part of the roof, and any loft space that you have above the bedroom ceiling. Air needs to flow - think soffit vents and ridge vents.

Also consider that while Celotex provides better thermal insulation, rockwool provides better sound insulation, especially the acoustic batts.

Disclaimer - I'm not a builder, but have done a complete refurb on my dormer bungalow, including insulation to building regs.

Cheers
Richard

Thank you Richard.

For the floor between garage and bedroom I have decided to pull down the garage ceiling and insulate from below (based on having to re-plasterboard if I do a false ceiling anyway!). This morning I picked up 8 sheets of 140mm insulation boards (celotex and ecotherm), foil on both sides. I intend to use this pushed up between the beams. Question, Should i leave a gap between this insulation and the floor above or push it hard up to it?

The celotex brick idea is based on information I've googled:
http://www.finehomebuilding.com/CMS...Homebuilding/Articles/230/021230089-1_xlg.jpg
http://mn.gov/commerce/energy/images/kneewall.PNG
http://www.energysmartohio.com/blog/how-to-insulate-and-ventilate-knee-wall-attics
This seems to imply that these openings require sealing which rockwool stuffed in would not achieve.

I don't intend to replace the polystyrene, certainly don't intend to pull down the plasterboard to do this. I 'might' look at sliding new insulation boards down from above at some point but I'll have to find some cheap as it would take lots. I am going to deal with the electric cabling though.

Regards Paul

Paulrsm · 3 Jan 2014

wrightwoodwork said:
The vapour barrier is fitted to all external walls that have insulation it can be in the form of foiled back plasterboard or visqueen vapour barrier. It is not fitted to the ceilings. The combs in the Dormer rooms gets a vapour barrier. Insulation in a loft in scotland is to be 300mm 1st layer going between and a second layer going across at right angles. It should come on to the internal wall head or in your situation on the insulation in between the rafter at the combs. There should be 50mm gap between the insulation and the sarking boards. The insulation goes under cables over pipes. Do not block off ventilation to the roof space or you will be contravening scottish building regs. In your garage area the ceiling should be insulted how you do it depends on how much you want to take like lifting floors or removing the ceiling which is a bit extreme and unnessary you could do a false insulated ceiling depending on how much room it should achieve a u value 0.18w/m2 K

Thanks for the reply.
I'm still struggling to understand vapour barriers. In my house the plasterboard on the knee walls does not have a foiled back. So it appears to be, Inside, standard plasterboard, rockwool insulation, side loft space then roof wood. Is this as it shoul be? Same on the pitched roof part except polystyrene instead of rockwool.
Sorry but I don't know what the 'combs' are?
As for the garage ceiling see my post above.

Regards
Paul

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