Underfloor Insulation

Waz5

I'm getting mix info with some people saying use Kingspan/Cellotex and other saying use Rockwool.

new_owner

Down to your decision Do some research on the options posted.

Rockwool will be the cheapest option.
Kingspan will have the best thermal value.
Sheep/hemp/fibre will give the best breathability vs thermal

Look at the pro's and cons of each.

new_owner

Waz5 wrote: »

I'm getting mix info with some people saying use Kingspan/Cellotex and other saying use Rockwool.

For a 1900's house I would say hemp/sheep

For a cellar that cooler you must think about moisture and when you insulate the cellar ceiling the cellar will get cooler still. Any moisture in the air will condense and you dont want that to be your wooden beams. venting is the way the house was designed to remove moisture and sticking insulation will slow/stop that process.

There is no point saving money insulating if you cause problems with damp.

cyclonebri1

new_owner wrote: »

Cellotex or Kingspan are recommended for newish buildings not older buildings which have 1 requirement, breathing. It will certainly cold bridge on a sub vented floor.

Fibre board, sheeps wool, hemp are a the ones that spring to mind that will work with an older vented building. Man-made materials are very good at insulation but not at dealing with moisture and as for cost... kingspan vs sheeps wool is around the same price.

But, the property is 1900 if I recall, since that era they have had the same ventilation provision as they do now, ie, external airbrick systems, pre cavity or cavity? doesn't really matter, they had vents, pre Victorians realised sellers got stale.

Also figure that sellers were usually for a purpose, storage. That needs to be dry.


New Owner, can you site 1 example of the better insulators causing issues please???

new_owner

http://www.english-heritage.org.uk/publications/eehb-insulation-suspended-timber-floors/eehb-insulation-suspended-floors.pdf

http://www.scotland.gov.uk/Resource/0040/00409101.pdf

http://www.engineeringtoolbox.com/water-vapor-saturation-pressure-d_599.html

http://issuu.com/ruthbusbridge/docs/ruth_busbridge_msc_aees_thesis

Ask yourself. Cavity wall insulation/ loft / floor insulation etc what is the risk of condensation by cooling wall/floor etc.

Thermal bridge / wicking need to be considered before spending money. The last thing you want to do is cause rot.

Get something that works with the house if you can.

More issues are caused in older properties by moden materials (damp being the top runner)

There are always risks but its your house and if you feel that the risk is so small that its not work worrying about then dont worry about it

I did enough looking into it and decided that it was not worth it and used Hemp

Just another thing. I read somewhere that kingspan (solid board) etc shrinks. I cannot remember the time frame (10 years springs to mind, but I cannot remember if it 10% )

Waz5

Thank you both for your input much appreciated. The strange thing is I had a quick look outside and can't see any airbricks on the external wall in our living room. I think I need to do a bit of investigation's into where the cold air is coming from.

new_owner

cyclonebri1 wrote: »

But, the property is 1900 if I recall, since that era they have had the same ventilation provision as they do now, ie, external airbrick systems, pre cavity or cavity? doesn't really matter, they had vents, pre Victorians realised sellers got stale.

Also figure that sellers were usually for a purpose, storage. That needs to be dry.


New Owner, can you site 1 example of the better insulators causing issues please???

They were very drafty with open fires and not gas central heating and draft proofing and showers.

Moden living is a big cause. Its a tribute to the victorians that the houses are still standing and even with our very wet lives, coping well

bbf

Considering doing underfloor insulation of suspended timber from from below, via small crawl space using wool or hemp (mainly due to close proximity of working with it above my face!)

Not entirely sure about the membrane. Working from below, I was expecting to use a membrane stapled to the joists with stainless or galvanized staples. Non-breathable polyethylene membranes often come in a large 4x5m sheet, but appear to only be useable when fitting from above and so on the warm side. When fitting from below, the membrane doubles as the support (i.e. serving as 'netting' + membrane in one), and the English Heritage document cited earlier states this should, in this position on the cold side, be a breather membrane, not polyethylene.

Has anyone done this before? I'm wondering if staples are OK, or does it need battens? Also there's some variability in breather membranes. Alternatively I could just not use any membrane, and use netting instead, but I think that will continue to let draughts in.

globalds

I had the idea of just putting a DPM onto the floor boards beneath the underlay and then just putting the carpet back on top ..This would definitely stop the draughts through the floor.

I could use Tyvec breather membrane instead as I can get hold of that fairly easily ..just concerned that it might well allow air to be drawn in as the room warms up

I am less concerned at insulation at the moment ..It is just the airflow ..It is huge ..you can feel it through the carpet .

bbf

You need both draught reduction and insulation. Foil is a great draught barrier but awful insulator. Wool is the opposite. Both together are likely what you need.