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Beam and block or Beam and insulation floor for UFH


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#1 jimbo_1

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Posted 21 November 2009 - 02:08 PM

Hi we are just working through building regulations for a new home. The architects has suggested using a beam and insulation flooring as he says it will reduce on excavation. Rather then using a standard block and beam. We are intending to have underfloor heating and we also need to put down a radon barrier. Does anyone have any recommendations for the best and most economical system? I am also unsure at what stage the underfloor heating goes in on the beam and insulation systems. Thanks.

#2 temp

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Posted 21 November 2009 - 04:21 PM

A beam and block floor would look something like this:

Floor covering
Reinforced Screed with UFH pipes in
Plastic sheet
Insulation
Beams with concrete block between.
Void
Ground

A beam and insulation floor would be similar:

Floor covering
Reinforced Screed with UFH pipes in.
Plastic sheet
Insulation (possibly not required?)
Beams with Insulation blocks between
Void
Ground

I'm not quite sure where the radon barrier goes. Ask your architect. The plastic sheet above is to stop water from the screed getting into the insulation and to act as a vapour barrier. The void under the floor would be ventilated with air bricks or "periscope vents" to the outside.

I'm not sure which is cheaper to build. Probably not much in it.

Have you got to the roof design yet? We have a "room in the roof" type house. I regret going for a roof design that puts the insulation between the rafters. If I was building again I would put the insulation between AND above the rafters. We had good builders but it's a soul destroying job cutting insulation to fit between the rafters. This means it tends to be done badly with small gaps that let air through. Putting a layer above the rafters allows the sheets to be butted tightly together with minimal or no gaps. The joints can also be taped with aluminium foil. This should greatly reduce air leaks making the insulation much more efficient. The alternative is a SIP roof where the whole roof is assembled from solid sheets of insulation with OSB either side - but that's probably more expensive.

The other thing I'm a fan of is MHRV. Best decision we made was to install one of those.

(Message edited by Temp on November 21, 2009)

#3 temp

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Posted 21 November 2009 - 04:24 PM

PS. Milbank floors gave us a good quote on our Beam & Block floor and I see they also do an insulated block system...

http://www.milbank-floors.co.uk/tetris_home.shtml#tetrisblock

It depends where you are in the country as the cost of transportng the beams can be a factor.

(Message edited by Temp on November 21, 2009)

#4 lukeb35

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Posted 06 December 2009 - 07:16 PM

We installed an UFH system in a house that uses the insulation + beam system, I forget the trade name for that system but from my reckoning its pretty poor.

The concrete beams themselves are only insulated by about 25mm polystyrene underneath the beam, which doesn’t have a particularly great U value so I fear cold bridging through the floor on every beam?

During work on the site you will find the ground floor the most treacherous landscape ever crossed by man as one heavy foot on the polystyrene will have you through the floor.

A rodent under the void beneath the house, which is totally possible knawing away at the insulation therefore leaving you with nothing holding your floor up.

The insulation itself is not strong, therefore the screed does not have much of a solid base to be laid, therefore I would worry about the actual strength of the floor.

I’ve just remembered the floor is called JETFLOOR!

And I think it’s the biggest cut corner lash product I think ive ever seen on site.

But it’s only my grumpy opinion of course.

Block and beam = excellent. And we’re not even floor sellers.

www.soloheatinginstallations.co.uk

#5 dream6

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Posted 14 July 2010 - 07:10 PM

I am contemplating using jet floor, has anyone actually used it, who can comment on the comments above? to my mind it has good a good u-value and I could see why, its been around for a while and I can find no evidence of rodents nashing through it, also it has a nice not too deep profile concidering the insulation is built in.

Has anyone used it here?

Many thanks

ps. No, I don't work for Hanson:-)