Underfloor Insulation & Extra Roof / Rafters Insulation?

[pdtnc]

Hi, I've not posted on here for ages but we do love our Navitron Solar Hot Water panels & Thermal Store in summer

When we had our kitchen floor replace during house renovations I specified insulation between the flooring joists as we were having a slate tiled floor and i wanted to keep it nice and warm.

I'm wondering what the best way would be to fit the same under the living-room floor (this is the original flooring with only 18" crawl space)?

Would it be best to get some plastic mesh to retain the Rockwool / Glass fibre insulation between the flooring joists and just staple it up or is there a better method?

Also our roof-space is a mixture of about 60-70% New with Tyvek membrane and Old Lats / Slates & Mortar for 30-40%, if I want to use rockwool between the roof (Rafters? the Angled sloping bits with the slaters lats nailed to) 1/ do I need to line the old part internally with Tyvek or similar first? 2/ Is it necessary to fix batons before over-boarding the insulation? (it feels illogical to have to space-off the boarding for an air-gap)

any help greatly appreciated
thanks

[Countrypaul]

If there is direct access to the bottom of the roof slates you are likely to have a cold roof space rather than a warm one. As such the insulation should be on the ceiling of the floor below - any insulation between the rafters below the slates is likely to be almost worthless as the space will need significant ventillation to prevent condensation.  Your best move might be to increase the amount of insulation on the loft floor and leave the roof as is.

Paul

[pdtnc]

Thanks Paul,
I'm boarding some of the floor out in the loft for storage and wanted to try and keep the temperature a little bit warmer up there so things don't get damp or too cold. Could I staple that reflective bubble-wrap stuff to the underside of the rafters and leave the void between that and the slates empty?

Is it possible to make a 'warm space' around the boarded area in a cold roof space so that the rest of the un-boarded area is still free to circulate fresh air?

[Countrypaul]

I'm sure you should be able to effectively build an insulalted storeroom within the attic space (especially if it is an older style roof and not one with roof truses everywhere). I have never done so, so cannot advise on how best to go about it though others on here may well be able to do so.

Paul

[pdtnc]

Thanks for the input

[pb]

Hi, I've not posted on here for ages but we do love our Navitron Solar Hot Water panels & Thermal Store in summer

When we had our kitchen floor replace during house renovations I specified insulation between the flooring joists as we were having a slate tiled floor and i wanted to keep it nice and warm.

I'm wondering what the best way would be to fit the same under the living-room floor (this is the original flooring with only 18" crawl space)?

Would it be best to get some plastic mesh to retain the Rockwool / Glass fibre insulation between the flooring joists and just staple it up or is there a better method?

If you want to use rockwool then yes, you can just staple chicken wire to the joists and then lay the rockwool batts on top.  Alternatively you could fit timber battens along the sides of the joists and then lay Celotex panels on top.

Also our roof-space is a mixture of about 60-70% New with Tyvek membrane and Old Lats / Slates & Mortar for 30-40%, if I want to use rockwool between the roof (Rafters? the Angled sloping bits with the slaters lats nailed to) 1/ do I need to line the old part internally with Tyvek or similar first? 2/ Is it necessary to fix batons before over-boarding the insulation? (it feels illogical to have to space-off the boarding for an air-gap)

any help greatly appreciated
thanks

Breather membrane not absolutely necessary but probably a good idea.  If you are putting insulation between the rafters then there needs to be a continuous air gap on the outside so that air can circulate around the cold side of the insulation.  It isn't necessary to have an air gap on the inside.

[pdtnc]

Thanks, I think I've got things straight in my head now.
First job is, I'm going to strengthen the roof joists on the old-build part of the house before loft boarding

[pb]

I'm boarding some of the floor out in the loft for storage and wanted to try and keep the temperature a little bit warmer up there so things don't get damp or too cold. Could I staple that reflective bubble-wrap stuff to the underside of the rafters and leave the void between that and the slates empty?

You could, though I've never been very convinced that the reflective bubble-wrap stuff (or any of the "super-foil" type of products) are worth the money.  If you want something to go under the rafters and just take a bit of the chill off the roofspace then polystyrene sheets might be a good option.  But note that if you reduce the airflow through that space then you risk making the loft more damp rather than less since it will still probably drop below the dew point at night.

If you've got the time and/or money then your best option would be to convert it to a warm roof (primary insulation between/under rafters and a largely airtight envelope) which would bring your loft within the heated envelope of the building.

[pdtnc]

Cheers
I'll probably go for the approach of pitching a tent (so to speak) in the attic which will be surrounded by the normal cold roof space. tho' the polystyrene thing might work well for me either.

[alex2504]

I insulated my loft with an additional 4 inches and also fitted 6 inches under suspended floor supported by chicken wire which has made a big difference to heating bill, but I am now getting bothered with mould on north facing walls with poor ventilation. Also just purchased a co2 monitor and got a shock when it read over 3,000ppm, and this is with the double glazing trickle vents all full open.

Now considering MVHR system... Seems to be never ending with saving the plant..