insulated foundation

ivorfa

I am installing an insulated foundation system and want to install underfloor heating the company recommends puting the steel mesh in on top of the 200mm of insulation and cliping the pipes to this and covering with 100 mm concrete.My problem is I am using ICF for my construction and the props to support the walls have to be bolted to the floor useing 100mm bolts so i would puncture the pipes. Would it be possible to put the pipes on top of the 100mm concrete and cover with 50 mm lightweight screed. If anyone has an answer to this problem it would be much appreciated i have checked with my ICF installer and can not use a shorter bolt to support props.

Shield

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Poor Uncle Tom

ivorfa wrote: »

I am installing an insulated foundation system and want to install underfloor heating the company recommends puting the steel mesh in on top of the 200mm of insulation and cliping the pipes to this and covering with 100 mm concrete.My problem is I am using ICF for my construction and the props to support the walls have to be bolted to the floor useing 100mm bolts so i would puncture the pipes. Would it be possible to put the pipes on top of the 100mm concrete and cover with 50 mm lightweight screed. If anyone has an answer to this problem it would be much appreciated i have checked with my ICF installer and can not use a shorter bolt to support props.

Putting your UFH pipes into a 100mm thick screed is using that 100mm of thickness as your thermal store which will release heat slowly to the rooms above. Adding 50mm more on top of the concrete screed means you now have 150mm thickness to heat up and will most probably delay further on/off response times and make the overall system more laboured and cumbersome. You will be heating extra concrete for nothing.

The flooring system which works best with ICF type construction is a concrete sub floor to run supports, etc, off. Once this is done put the insulation over the sub floor and the UFH pipes over this with a screed poured on top. Some of the ICF companies have insulated trays specifically for the UFH pipes to sit in before pouring.

You could speak to your own engineer/architect, the ICF companies engineer, your BER assesor (regarding insulation) before making your mind up.

ivorfa

I have thought about doing that but it seems like a lot of expense for insulation when I already have 300mm of insulation under the concrete slab by using the insulated foundation system

Poor Uncle Tom

So you already have a concrete slab in place?

Max Moment

Poor Uncle Tom wrote: »

Putting your UFH pipes into a 100mm thick screed is using that 100mm of thickness as your thermal store which will release heat slowly to the rooms above. Adding 50mm more on top of the concrete screed means you now have 150mm thickness to heat up and will most probably delay further on/off response times and make the overall system more laboured and cumbersome. You will be heating extra concrete for nothing.

+1 to this.

However, if you are set on using the sub-floor for your UFH there is no reason you can not get the ICF construction to work without having to penetrate the slab with bolts. There are a number of ways of propping using proprietary systems available which do not have to be bolted to the slab.

For example, placing already cast Concrete blocks (AKA Kelly blocks) on your sub-floor and bolting the props to these instead of the slab is a widely used alternative. The ICF company is just being lazy IMO. Your Engineer will advise you on this of course as a detailed design needs to be carried out.

This may well turn out a lot cheaper than an extra screed and insulation on top of your sub-floor.

Another alternative would be to 'set out' the exact locations where the prop bolts are to be placed before placing the UFH pipework and ensure the installer keeps clear of these areas. You can then bolt away freely.

On another note, drilling and fixing 100mm long bolts through a 100mm thick slab could potentially cause your Radon Barrier / DPM to become punctured which is seriously compromising it's effectiveness.

ivorfa

Will take a look at the kelly blocks this may well be my answer as for punctureing the membrane this should not be a problem as it is in between the layers of insulation
thanks for the help