Minimum 1st Floor Insulation & Screed Depth

BarneyMc

I've hollow core slabs installed in my house and will be putting UFH in both floors. On the first floor I'll be using a liquid screed but what's the minimum depth that can be used. What's the minimum recommended insulation thickness on the 1st floor also?

hexosan

By liquid screed I assume you mean a hemihydrate screed, if so the minimum they recommend is 50mm. If you go with a concrete screed it's 75mm.

Liquid screed works out at roughly €16-€18/m2 @ 50mm

Concrete works out at roughly €5-€5.50/m2 @ 75mm
But with concrete you have to also include sheets of steel mesh A142 normally (€22 per sheet, covers roughly 11m2) + the labour to lay the floor.

The minimum insulation is normally 25mm PIR which is roughly €16.50 per sheet which is 2.88m2 so roughly €5.70/m2

acehigh76

BarneyMc wrote: »

I've hollow core slabs installed in my house and will be putting UFH in both floors. On the first floor I'll be using a liquid screed but what's the minimum depth that can be used. What's the minimum recommended insulation thickness on the 1st floor also?

unless building regs have changed I didn't think you need insulation on a first floor .as its internal .only on the ground floor to prevent cold bridge.unless its different with ufh . we used to have 150 mm slab 75mm concrete

BarneyMc

acehigh76 wrote: »

unless building regs have changed I didn't think you need insulation on a first floor .as its internal .only on the ground floor to prevent cold bridge.unless its different with ufh . we used to have 150 mm slab 75mm concrete

Its just to improve responsive time

galwaytt

acehigh76 wrote: »

unless building regs have changed I didn't think you need insulation on a first floor .as its internal .only on the ground floor to prevent cold bridge.unless its different with ufh . we used to have 150 mm slab 75mm concrete

...er, and what do you think the slabs are resting other than cold walls... ? Of course you have to insulate FF.

acehigh76

what cold walls ? The cavity insulation should ensure they are not cold walls.

galwaytt

acehigh76 wrote: »

what cold walls ? The cavity insulation should ensure they are not cold walls.

Sorry, but your walls are standing on the foundations/ ground, uninsulated. . They're a huge cold bridge. Every morsel of heat put into the floor would be lost to the walls before it gets any chance to heat the rooms.

You have to insulate, and not a token amount either. Besides, you have to allow the screed to expand and contract as well. ... and insulation is how you do it.

acehigh76

then why have cavity insulation at all if there's this "huge coldbridge"between it and the house. lets get rid of it and go back to styroslab . you seem to know more about coldbridge than anyone in the industry. I understand your point about expansion but your coldbridge argument doesn't stack up . the only time you insulate a ff against coldbridge is when part of the floor is external in which case insulation is fixed to the underside of the slab.

hexosan

@galwaytt
If Quinnlite's are used for the first two rows at ground level and then the ground floor screed is poured on top of insulation the cold bridge at first floor level will be next to none existent.
How are you claiming this isn't the case.

The main reason to insulatied at first floor level is for a faster responds time from the UFH set up.

acehigh76

or if you re that bothered insulate the outside of the building at ground level that's your coldbridge, not the foundation, they are situated at a depth so they are insulated by the ground. insulating the ff to prevent coldbridge is a bit like shutting the barn door after the horses have bolted

hexosan

acehigh76 wrote: »

or if you re that bothered insulate the outside of the building at ground level that's your coldbridge, not the foundation, they are situated at a depth so they are insulated by the ground. insulating the ff to prevent coldbridge is a bit like shutting the barn door after the horses have bolted

I don't agree with this statement, while the ground acts as a natural insulator at a certain depth this isn't the case with a footing.
Either way the ground will never be at 19/20+ degrees (inside temp of the house) so as a result you will lose heat from the rising walls through a cold bridge. Hence why you'd use Quinnlite's and floor Ins to reduce the cold bridge effect.

acehigh76

I didn't say they d be warm but they won't be cold as galwaytt said. they are at a depth that offers insulation otherwise moisture will freeze and cause cracks in the concrete. I worked on apples new headquarters in cork last year and we used insulation on the outside of the building to prevent coldbridge. There were no quinnlites used and that would be one of the most energy efficient buildings around right now. anyway I didn't want to get sidetracked. I just had a problem with his comments when it seems he knows nowt .

BryanF

acehigh76 wrote: »

I just had a problem with his comments when it seems he knows nowt .

relax! Anymore of this and you'll be banned.

acehigh76

What I meant was I meant was I don't like being patronised .I have no problem if someone s wrong

BryanF

acehigh76 wrote: »

What I meant was I meant was I don't like being patronised .I have no problem if someone s wrong

banned. Read the forum charter before posting again

galwaytt

I currently have 3 floors over different construction methods, all with UFH & I have UFH for 20 years.

I am not speaking from a position of ignorance.

hexosan

galwaytt wrote: »

I currently have 3 floors over different construction methods, all with UFH & I have UFH for 20 years.

I am not speaking from a position of ignorance.

Can you respond to/explain the cold bridge issue at First Floor level