My first post, so - hello! My OH and I have a 1960s bungalow with a suspended wooden floor, the boards are straight planks nailed to the joists, apparently the joists are supported on sleeper walls. This info comes from the people who installed our shower cabinet, we haven't yet taken up the floor to see for ourselves. There's no underfloor insulation.

We want to install electric underfloor heating plus a good quality wood floor finish. The decision on electric heating is final. We'd appreciate some advice on insulating the floor, please - this is going to be a d.i.y. job apart from connecting the electrics. Is the kind of thin pad or roll insulation that comes with electric UFH systems good enough to insulate to recommended modern standards, or should we just bite the bullet, take the floorboards up and insulate underneath? There's about a foot of air space beneath the boards and I can guess what the answer's going to be, but we'd really appreciate your opinions. Thank you!

Electricity will eventually be the only fuel for the masses.

It is mad to use it directly for heating. If you use a heat pump you will get 3.5 > 4 kW of heat for each kW of electricity.

Use a wet system and then you can choose what fuel to use to make it work.

Insulation should be as good as possible and air tightness is very important too. Something like the value from 20mm of pur over the joists and 100mm between would be a minimum I would say.

Diotima,

your friend is not giving you very good advice. Wet systems are by far the most fuel flexible and are not necessarily horrendously expensive. If you're really considering future energy supples, why would you choose a system that only gives you 1kw out for every kw in versus a system which will use only 25-33% of the power (electricity in this case) compared with your solution? The beauty of a wet system is that you have unlimited choice in how you heat the working fluid: could be a condensing boiler (oil, gas etc.) a wood burner (not good for urban areas), solar hot water or even solar PV. The latter is the most expensive so you would be ill advised to install a system which only gets an "efficiency" of 100% - with a heatpump you would need only 1/4 the amount of PV cells to give the same heat output as your inflexible electrical system. It might be cheaper in the short term, but will end up being by far the most expensive in the long run. A case of penny wise, pound foolish? If you're going to do the right thing, do it. Your US military friend might be right that the UK can generate electricity in the future - but surely it's better to minimize the amount of generation that's required? If everyone followed your short-sighted approach, then it would be very difficult to meet the generation load in the future.

Bite the bullet and put in a wet system - there's plenty of "staple-up" systems with heatspreaders that, with good insulation, are pretty much as effective as wet systems embedded in concrete. You talk about putting your money where your principles are - it doesn't sound like it from where I'm standing.

Best regards,

Paul in Montreal.

Diotima Hi I have copied each question and tried to answer each aspect.

" And what does all this have to do with my request for advice on insulating our floor?"

If you want advice from this forum You will get the opinion of the writers as well which I largely agree with try reading it and listening to it.

"Thank you for your response, Paul. Apart from the fact you don't know what advice we've had from our American friend,"

Maybe you would like to tell us what you have been told so we may take on board this aspect - maybe we will come to the same conclusion as you.

No-one is suggesting you use your existing boiler for this project, but that you replace it with a Ground Source Heat Pump that will heat your whole property not just one room as one person said this type of machine will turn 1kw of electricity into 4kw of thermal energy which can also be used as cooling i know if I had sufficient ground to site the drill rig I would go for similar system. I live in a terraced house.
Incidentally the box that does everything is the size of a small fridge How big is your boiler? now.

"our existing oil boiler isn't suitable for powering a hydronic system."
What is a """"hydronic system."""" ? Are you trying to say water based or wet system ?

Arnold

Hi Solar Bore

Thank you for your response. What I asked was about insulation of a suspended wooden floor, and this is what I need an answer on. If this forum has people willing to answer that question without driving me nuts - I'm a very busy web developer and my clients' deadlines are usually 'last week' - I will, *perhaps* revisit our choice of heating. Along with the heating system, we also have to deal with replacement windows (more choices), widening doorways; making the bathroom and kitchen suitable for a wheelchair-bound user; new front entrance and ramp; rewiring; and redecoration after all that. One of us also has a medical condition which means that noise generation has to be taken into account.

All this is going to stretch our budget severely. We have 40 square meters of unshaded south-facing roof and we hope to have the money sometime in the future to install solar panels for hot water.

From having a further look around this forum I get the strong impression it is dominated by a small group bent on promoting their personal agendas regardless of the question asked. Perhaps this is why such a potentially valuable forum only has something under 600 members. A professional list I'm on - webdesign-l.com - has more than 10 times that number, perhaps because we stay on topic and answer the questions we're asked, and don't respond when we can't.

Thank you for your input.

It is good advice, it's just not practical for the situation my partner and I are having to cope with, and *it's off topic for the question asked*. The specific question was about insulating a particular type of floor, and I anticipated I would find the most knowledgeable, up to date, advice here. I included the comment about electric heating because the question specifically refers to the insulation generally used in that type of heating - relevant, I think. We're limited on capital for the necessary works, not on income to pay for our electricity usage which is monitored carefully, but we don't intend to remortgage as our plans are to sell this property in six to seven years and retire abroad.

I came here looking for advice on a clearly defined question, my partner and I having made decisions, after much research, on how to cope with difficult circumstances, and have been berated for making a choice not to the liking of certain members of this forum who don't know the circumstances and don't have to deal with what we have to. My comment about the forum is valid, it's the impression I have. Deal with it.

Apparently this forum is moderated, so I shall be contacting the moderator to have my membership cancelled. I won't be posting in this forum any more, or even reading it, it's clearly a waste of my time.

More or less to reiterate waht moogaloo has said... i started to lift my floorboards, firstly to insulate and inspect the joists. By the time i'd insulated (lots of time and effort involved) I felt i was 75% of the way to installing UFH, so thats the route I went down. We are installing wet system fed from an accumulator tank, heated with a pellet boiler. If you have access to a large south facing roof i would consider, as the others have said a wet sytem, with a thermal store/accumulator tank which can house more tahn one coil so you can heat the tank from solar/other sources. In the long run this will give the most flexibility.

"Staple up" means walking around in the basement and fixing to underneath of the ground floor boarding easy! Might not be so nice in the UK as even crawl spaces are rare here as you know.