Insulation in floor

Barr

Hi All



Quick question regarding insulation in flooring on a new extension.

What does it need to be to meet the latest regulations?


Thanks
Barr 

Dudda

It needs to be 0.21 W/m2K or if you have underfloor heating 0.15 W/m2K but I'd look for 0.15 or lower at a minimum. It will also depend on the overall design and DEAP calculation.

Don't understand why people aim for the absolute minimum when it comes to insulation. Get as much insulation and airtightness as you can afford in your new extension. You can't easily go back to the floor and add more later. You can upgrade the kitchen or get the granite worktop in 5 years when you've more money but you can't improve the insulation.

Barr

Dudda wrote: »

It needs to be 0.21 W/m2K or if you have underfloor heating 0.15 W/m2K but I'd look for 0.15 or lower at a minimum. It will also depend on the overall design and DEAP calculation.

Don't understand why people aim for the absolute minimum when it comes to insulation. Get as much insulation and airtightness as you can afford in your new extension. You can't easily go back to the floor and add more later. You can upgrade the kitchen or get the granite worktop in 5 years when you've more money but you can't improve the insulation.

Thanks Dudda , the quote we have got just has the size of the insulation , they have 100mm for the floor. How does that equate to the above

Dudda

Barr wrote: »

Thanks Dudda , the quote we have got just has the size of the insulation , they have 100mm for the floor. How does that equate to the above

Poor to average. Definitely a fail if you have underfloor insulation heating*. What brand or make is it and I'll try and work out a u-value? I'd be looking for 150mm of a PIR type insulation and about 200mm-250mm of EPS which would be cheaper.

Barr

Dudda wrote: »

Poor to average. Definitely a fail if you have underfloor insulation. What brand or make is it and I'll try and work out a u-value? I'd be looking for 150mm of a PIR type insulation and about 200mm-250mm of EPS which would be cheaper.

I am meeting with the builder later today so will try get more info.

What would you recommend for the walls which are being built by block?

Dudda

Barr wrote: »

I am meeting with the builder later today so will try get more info.

What would you recommend for the walls which are being built by block?

Sorry in above reply 'underfloor insulation' should have read 'underfloor heating'

Is it an external cavity wall? You can usually get away with 110mm Kingspan Kooltherm in a 150mm cavity which will just meet regs but again I'd try and aim higher. This isn't college where scraping a pass is good enough.

Another note is insulation is only as good as it's installation. If it's poorly fitted with gaps then the heat will flow through the gaps and all the money you spent on the insulation is wasted.

Barr

Dudda wrote: »

Sorry in above reply 'underfloor insulation' should have read 'underfloor heating'

Is it an external cavity wall? You can usually get away with 110mm Kingspan Kooltherm in a 150mm cavity which will just meet regs but again I'd try and aim higher. This isn't college where scraping a pass is good enough.

Another note is insulation is only as good as it's installation. If it's poorly fitted with gaps then the heat will flow through the gaps and all the money you spent on the insulation is wasted.

How the builder described it (from memory) is the wall will be 450mm thick , 150mm block each side , with 100mm insulation and 50mm gap for air.

I'm sure he mentioned Kingspan as the brand type.

Dudda

Barr wrote: »

How the builder described it (from memory) is the wall will be 450mm thick , 150mm block each side , with 100mm insulation and 50mm gap for air.

I'm sure he mentioned Kingspan as the brand type.

Have you an architect or engineer on this who'll be signing off on the project? Who did the drawings for you that decided the wall build up and 150mm blocks as it would be more common to use only 100mm blocks for an extension.

Ask the builder to forward you the data sheets for the wall and floor insulation he's proposing to use and then upload them for us as even Kingspan have lots of different types of insulation.

Barr

You are right , I have the quote sheet in front of me now.





For the walls it says 350mm external cavity wall and insulation


100mm Single Block Wall , there is 100mm insulation , 50mm gap , then another 100mm wall



For the floors (non heated ) it says :

Floor insulation ; 100mm thick rigid board insulation

Insulating verticals edges

Floor base average thickness 150mm



I don’t have an engineer yet as we are at the stage of getting quotes for the building.

That is why I was hoping to be a bit more clued up in what we should be expecting as a good standard.

Gumbo

Barr wrote: »

You are right , I have the quote sheet in front of me now.





For the walls it says 350mm external cavity wall and insulation


100mm Single Block Wall , there is 100mm insulation , 50mm gap , then another 100mm wall



For the floors (non heated ) it says :

Floor insulation ; 100mm thick rigid board insulation

Insulating verticals edges

Floor base average thickness 150mm



I don’t have an engineer yet as we are at the stage of getting quotes for the building.

That is why I was hoping to be a bit more clued up in what we should be expecting as a good standard.

No point in buying a stable after the horse has bolted.
Get your engineer/architect/designer on board now to draw up a technical design that you can then get prices from builders. Waste of time and effort otherwise.