Insulating Under Floor-Draughts

[Harden Long]

Hi Everyone
I posted this in the flooring forum but figured it might be more appropriate here.
We moved into a 1920's house a year ago and over the winter have been aware of how much draught comes up into the house from a fairly large crawl space under the house

I'd like to insulate down there-I have searched and seen suggestions about mineral wool held up by chicken wire onto the underside of the beams (although, and I know this is daft am worried that that would make it an attractive home for vermin??)

I have also read about polystyrene blocks that can be cut and wedged into the gaps between the wood rafters and saw some products on a popular DIY store. One was called Jablite Flooring Insulation Polyboard and the other Kingspan Thermaboard Urethane Insulation

So, please could I ask for your advice-what would you recommend??
To be honest the boards seem much easier to fit for a klutz like me but am willing to take advice
If the boards are the suggestion what thickness should I go for??

Many many thanks

 

[JerryM]

u need to separate the vermin aspect from the insulation.

u don't wont vermin full stop. the only real answer is to stop them getting in. if there is any indication that they are their ie droppings then u need to inspect the whole of the cavity area to block off any potential entrances. obviously don't block any vents. use mortar or the like where possible to block off ie not wood which can be eaten away.

on the insulation it’s down to your choice (the bco recommended the mineral wool and chickwire). the key point is to draft proof. because heat rises the temp at floor level is low compared to that at ceiling ht. so the benefits of the insulation are not big. the cavity is ventilated to keep the joists dry and this is why the draft proofing is so important - the living room just becomes an extension of the ventilated void otherwise.

in the end i simply used frame sealant underneath mine. in terms of thickness if u wanted to go Rolls Royce then 50 or 100 would be good enough (lofts were only 150 not long ago).