Any advice on best product to insulate under a suspended wooden floor over a cellar??
many thanks
I would use a rigid insulation boards (like Celotex or Kinspan) between the floor joists and held in place with battens
I would use a similar approach of boards held by battens, but with a more ecological product like BioFIb, or Lain de Chanvre
“Créée en 2009 et basée en Vendée, Biofib’ Isolation est « La » marque 100% française de l’isolation d’origine végétale. Proposant des solutions d’isolation biosourcées, Biofib’ assure une maîtrise complète de la filière « du champ au chantier« , puisque le chanvre comme le lin sont produits dans un rayon de 100 km autour du site de production grâce aux agriculteurs de la coopérative agricole Cavac. Le chanvre comme le lin, sont des fibres très appréciées pour leurs vertus écologiques et structurelles. Elles offrent notamment, des caractéristiques thermiques, phoniques et hygroscopiques très intéressantes pour l’isolation.”
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Thankyou will look these up… what do you think re breathable membrane across the base of itall?? overkill??
I’ve done it with sheep’s wool in that situation. Very easy to fit and to hold in place. No dust either. I will be insulating my workshop ceiling with it this winter. I am currently lining the block walls with ply on studs packed with cleaned and processed black merino fleece offcuts I got for two quid a sack 
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so rockwool?? what did you hold it in place with??
No not rockwool, I never use it now for various reasons, not least the dust to which I am allergic!
In my house, it’s cork. It provides excellent thermal and sound insulation.
interesting… i have steered away from rockwool
any idea where from please??
Is that between the floor joists or on top of the floor?
The air sealing membrane over the rockwool and under the floor should prevent any dust. Unless you mean during installation?
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The best product is tricky as rigid foam installed correctly is a better insulation per mm compared to most others,
Loads of places
We have a thick layer of shredded cork under kitchen floor. Insulates and breathes.
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For example, here, but you can easily find cork at retailers of eco-friendly building materials
Well both I think, you couldn’t just support it with battens, you would have to board the ceiling, or it would always shed dust. It’s not particularly efficient compared with celotex or some of the eco products. Sheeps wool isn’t that efficient in simple performance terms, but will dry out quickly if it gets wet, is nice and easy to use or alter and is fire retardant. Celotex…won’t they have writs slapped on them soon ?(Grenfell). I think rockwool has a lot of energy to produce it, off the top of my head…I just hate the stuff really. If whoever invented it was a fitter he or she would have binned the spec before anyone got their hands on it - same old, a good idea for the plebs to use and someone in the office to make money from.
What’s the makeup Jane, suspended floor, cork then timber?
I have this Naofloor solid hardwood floor installed as a floating floor, with a special underlayment. But there are cork solutions for every type of installation.
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I laid cork lino flooring in my daughter’s apartment in London. It was lovely but her cats destroyed it in 3 years and my wife just told me about it recently. My daughter couldn’t face telling me. I’d boxed all the piping and fixed decent new skirtings too. I don’t want to know what happened to them because the electricians messed about with them…
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I’m sorry about all that wasted work! I have a lot of cork at home—under the hardwood floors, but mostly in the walls… 20 cm of insulation. No risk of cat scratches !
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