Building Regulations - floor insulation

[FresnoBob]

Evening everyone, sorry to be a pain.

1990 build house, Block and Beam floor, Expanded Polystyrene (the white crumbly stuff), DPM and Chipboard....we're ripping the Polystyrene, DPM and Chipboard up as it's pretty wonky and shoddy, and we're hoping to create a nice flat insulated surface that we can lay some tiles on.

Hoping to lay a new DPM, with Celotex or Kingspan and then screed on top.

Has anyone an idiots guide (yes, that's me lol) to current Building Regulations floor insulation requirements, and the insulating values of the upgraded insulations available. I'm assuming that Building Controls have became more strict with regards insulation, but this could be countered by the better insulating values of the upgraded insulation.

I haven't a great deal of space to work with, probably a maximum of about 110-120mm, so it would be nice if I could reduce the thickness of insulation, to allow the screed to be thicker.

Orrrr, am I best off just having a word with Building Control and seeing what they say?

 

[peca27]

Ground Floor's have to achieve a min. 0.22 w/m2/k value.

for example a 80mm of Kingspan Thermafloor TF70 should get it.........BUT

technically speaking you need a perimeter over area ratio + then take the relevant info from a reputable website like Kingspan. If you're working up against an external wall you may also need perimeter insulation.

But defo have a word with your Building Control inspector, I'm sure he'll help

 

[DevilDamo]

As mentioned above, you would be looking at achieving a u-value of 0.22.

For those who are tight on space (i.e. floor levels lining through), then you could approach a consultant (e.g. SAP assessor) to produce a trade-off calculation, which basically tells you what additional insulation needs to be added to the walls/ceiling to make up for the loss of insulation within the floor. I have had them done on a few occasions. Obviously there's a charge for this.

Or your BCO may be able to tell you straight away what they would be happy with.

 

[ajrobb]

The BCO can only tell you to do what is possible. If there is not enough space for sufficient insulation to meet current Part L Building Regs, then the BCO can only tell you to fit as much as you can. You might get better insulation with exotic materials but they must pay for themselves in savings over 15 years.

I'm not really convinced by long-term benefits of PIR. The foil on each side helps contain the heptane blowing agent but eventually (decades) it leaks away to be replaced with air and the insulation drops to that of EPS. However, it only has to satisfy the BCO.

 

[FresnoBob]

The BCO can only tell you to do what is possible. If there is not enough space for sufficient insulation to meet current Part L Building Regs, then the BCO can only tell you to fit as much as you can. You might get better insulation with exotic materials but they must pay for themselves in savings over 15 years.

I'm not really convinced by long-term benefits of PIR. The foil on each side helps contain the heptane blowing agent but eventually (decades) it leaks away to be replaced with air and the insulation drops to that of EPS. However, it only has to satisfy the BCO.

This is good to hear, as usual I had worried myself into a frenzy, thinking I was going to have to alter the front door to squeeze in metres and metres (slight exaggeration lol) of insulation.

I have heard that Building Control are fairly reasonable as well....I guess I shouldn't worry lol.