Insulating 1st floor on 1930's house

happyhero

Hi I have a typical draughty 1930's house with suspended floors and I understand a fair bit about insulating the ground floor. We have air bricks back and front on both floor levels and of course it gets pretty draughty under the ground floor and there is a void of about 10inches under the ground floor joists but what about the 1st floor?

I am not sure how the air bricks can do that much on the 1st floor as the joists are sandwiched between the ceiling below and the floor above so surely they can only ventilate within the 2 joists that they are located what do you think?

I am thinking of insulating the 1st floor as I am decorating there now. I realise that some heat may come up from below and insulating will stop this but surely this is a good thing, as heat from below is lost heat below and the air bricks in the 1st floor will be allowing cold in so insulating from this and thus preventing so much heat being stolen from below will be a good thing, wont it?

I was trying to find a good thin insulator with a good R value that I could place on top of the floorboards (and not create too much height) but other than a really crazily expensive one none seem that good so I then considered putting in Kingspan just under the floorboards, which would be a lot of work but seems my only option to insulate well, any ideas?

What do you think about me insulating the 1st floor, good or bad idea and reasons, any advice appreciated.

System

If you are putting money into insulation, use it on the external walls/floors and roof - insulating an intermediate floor if you have cold external walls will give you absolutely no benefit

(If you have cavity walls the airbricks are intended to ventilate the cavity rather than the floor)

happyhero

Ok thank you, we do have cavity walls and our house is a semi. As for the external walls we have not noticed that they are particularly cold. We did consider cavity wall insulation just to improve things but after talking to insulating companies and then experts on insulation it seemed that the insulating companies always recommended cavity wall insulation and experts always recommended against it for all the problems it could or would cause, i.e. they would say things like the house is not a new house but an old house designed to breath so filling up the purposely empty cavities is asking for trouble etc etc. Also they mentioned that insulation settles leaving cold spots at the top which causes problems later on, so basically we were put off the idea for now.