Under floor insulation. Cold rooms

[BMad]

OK I’ve trawled through the web trying to find a solution or even a reason for my problem but no joy! So I’m really hopping someone out there can help or point me in the right direct.
The property is an old converted minors cottage. Around 1900
The property has been renovated to a high standard but the ground floor rooms are very cold, even though the roof is insulated and the dry walls are insulated.
Ive just lifted the floor (created an inspection hatch) as my thought was to investigate insulating between the joists in the suspended floor, to reduce the cold coming up from the floor. I was expecting to find just earth but it’s been concreted.
There are no vents around the main property (except around the kitchen extension which was added to the cottage.
This also surprised me but with all the major renovations done on the property i can only assume this wasn’t required. I was told property of this type and age often didn’t have vents.
I’m now unsure what my best options are.
Could the cold be due to the concrete base under the suspended flora?
Could the problem be due to lack of ventilations, although everything is perfectly fine, looks like new under the floor, no damp, mould, looks crisp!
Could i lay kingspan or similar insulation directly onto the concrete slab as this would be much easier they putting between the joists?
Should i look at other reason why the rooms are so cold on the ground floor?
Ahhhh!
Help please........

 

[JohnD]

the wooden subfloor really ought to be ventilated with airbricks or similar - one every two metres on each side of the building is usually about right if it is of average size. There is a chance the subfloor wil be damp and this will cause the timbers to rot

If you do not have carpets then the floor will feel colder and may be draughty.

Yes, you can insulate the floor from underneath. A lot of people pack in loft insulation quilt and use garden netting stapled to the joists to prevent it falling out. I now recommend the white recycled quilt which is made from plastic bottles spun into fibre, and is not itchy like glass fibre. It is cheaper than kingspan and you will probably find it easier to poke through your trapdoor. Especially if you are working from underneath and it might fall into your eyes.

Use Climaflex or similar lagging (the thick BS grade) for underfloor pipes while you are down there

 

[BMad]

Thanks for the advice.

Although very little space between the concrete and floor, about 2-3 feet, so probably too tight to crawl under and fix insulation onto the joists. which is why i thought of just placing the insulation directly onto the concreate!
I agree with the venting but can not understand why this wasnt done when all this work was carried out, would have thought building regs would have required this, but as i say the building is very old and the main walls are built of stone, these are about 3 - 4 feet thick in places, which may acount for the air bricks not be put in!

could i get away with insulating directly on top of the concreate?