concrete floor and cellotex thickness query

[karenandoz]

Hi all - just a quickie - got a 200mm depth to make up to floor height of existing building in new extension, on top of concrete oversite. Would you (from a cost/ hand mixing cement issue) go for thicker cellotex, or thicker concrete (only needed 75mm of each to satisfy building regs).

What do you recommend as easiest/cheapest option?

Thanks all

 

[spada01]

Hi all - just a quickie - got a 200mm depth to make up to floor height of existing building in new extension, on top of concrete oversite. Would you (from a cost/ hand mixing cement issue) go for thicker cellotex, or thicker concrete (only needed 75mm of each to satisfy building regs).

What do you recommend as easiest/cheapest option?

Thanks all

Or option 3 - more hardcore under everything which is what I'd do and it's cheapest. MOT type 1 - about £40 per tonne delivered

 

[RedHerring2]

Have you allowed for a screed?

 

[karenandoz]

Hi - thanks for your reponses - concrete oversite already down, so hardcore not an option - thanks though.

The finishing screed will just be a latex one over the concrete, as we are laying electric UFH under lino - (antico or similar - so it's gotta be dead flat), so will only be a couple of mm thick.

 

[mointainwalker]

Now that you mention UFH, I think you would be wise to increase the insulation because :

1) It will minimise heat losses
2) If you have 100 mm + of concrete, the heat inertia will be very significant and the floor will take a long time to heatup/cool down.

Fairly unusual to combine electric UFH with a heavy screed/slab. Have you been through all the pros and cons ?

 

[karenandoz]

Thanks mointain walker
Have you got the time to enlighten us on pro's and cons? Do you reckon we should drop the floor to allow for heat reflective very expensive board that they always try to flog you with elec ufh? Or is there a better idea. We know we def want ufh. Thanks

 

[Deluks]

As you haven't yet laid the top layer, have you considered wet ufh? cheaper to run overall.

 

[karenandoz]

Thanks for your suggestion. I might have done the maths wrong, but i thought it wud be uneconomic for the one room we got to do (4 m x 5m) to install wet ufh?

 

[mointainwalker]

I never investigated electric UFH in great depth for myself, but everyone I know says it is expensive to use and the elements are also expensive to install.

It is mainly used ( as i read on these pages ) in small areas like bathrooms where it is not heating but taking the chill off . The main selling point seems to be it can be laid without a screed whixh makes it suitable for renovation. This is also why there is that stupidly expensive paper-thin "insulation" which is just an alibi to try to show that you can have thinness and insulation ( not )

Since you have a screed, most of the points above do not concern you and you should cost the electric against water UFH.

I do not know how typical it is, but there are frequent posts on the electrical forum about component breakdown with UFH heating. Might be worth your while doing a search.

 

[karenandoz]

many thanks for all your help mointainwalker - we have it in the bathroom - it heats the air aswell as it is higher voltage, which was what we were planning to use in the kitchen - but I will look in to it in more depth to check we are making the right decision, especially as we are on concrete and not a suspended wooden floor - all the best.