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Draughty floors in first floor flat

Hello, I have recently moved into a first floor (and top floor) flat that was build mid 80's with a block cavity wall construction. I have noticed it feels a bit draughty and the floors feel cold, especially so as it is a first floor flat and the flat below is occupied.
My first question is should there be a noticeable breeze within the cavity wall?
My front door is on the ground floor, this opens up into my bottom of my stairs that lead to my flat hallway. This porch area which isnt seperated from the stairs is aways very cold as there is no radiator down there (gas central heating)
I ventured down the access hatch underneath the porch area which is below the ground floor and i noticed a decent breeze,and cold as its about 4 degree C, blowing down the length of the cavity wall. I wondered if this is normal? I know there should be ventilation under the ground floor but didnt think it would be so breezy in the cavity. Does this not make my internal wall essentially an external wall (without the rain) as the outside air temp is blowing insde the cavity?
My bedroom above this wall where i witnessed the breeze is always 3-4 degree cooler than the rest of the flat, and my feet always feel cool when walking around in my socks within the flat. the walls also feel cooler than i would expect.
I took the carpet in my bedroom along the wall and the boards bellow (not floorboards but larger sheets of flooring) felt cold to touch. I also could feel a cold draught coming from the edge of the floor under the skirting board. Having someone living below me i thought i would benefit from their heat, but i appear to have unwanted underfloor cooling flowing through my flat!
I know i can seal these draughts along the edge of the floor and maybe add a better thermal underlay, but is this just masking the source of a problem?
There is no cavity wall insulation, and i believe the ground floor flat would need to agree to this being injected if i went down this route also? The ground floor porch area has no underfloor insulation.

So...basically what I need to know is, is a breezy cavity wall normal? and if not what could be the cause and how could this be rectified. If this is normal what is the best way to insulate my floors and walls (including a way if the other resident in the block didnt want CWI.)

Any advice would be greatly appreciated

Thanks in advance

1 Answer from a MyBuilder Insulation Installer

Hi iallan75
Your problem is not unusual and can be resolved. Where joists are let into a wall the holes created allow air through if the builder didn't take care with construction. These holes can be filled but without seeing the property it is difficult to give specific advice. Air movement in cavity wall construction is normal but again dependent on age and method of construction.
Chris law


Answered 30th Jan 2017

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