11357 Insulation

We've got an old farmhouse near Sulmona & it gets fairly cold there in the winter. The house has thick concrete ceilings to the ground & first floor. Are we losing a lot of heat out of them? I'm pretty sure there's no point putting traditional fibre/wool insulation on top of the concrete in the loft as the heat will already have been lost into the concrete but does anyone know if it's worth putting an insulative coating onto the surface of the ceilings? I'm guessing the cost might not be made up in savings but wasn't sure.

Thanks

Category

Building/Renovation

Hi
You could try insulation and plaster board, at least you would have a small airspace as well ........good luck

[quote=Dougie & Michelle;107495]We've got an old farmhouse near Sulmona & it gets fairly cold there in the winter. The house has thick concrete ceilings to the ground & first floor. Are we losing a lot of heat out of them? I'm pretty sure there's no point putting traditional fibre/wool insulation on top of the concrete in the loft as the heat will already have been lost into the concrete but does anyone know if it's worth putting an insulative coating onto the surface of the ceilings? I'm guessing the cost might not be made up in savings but wasn't sure.

Thanks[/quote]
Are you certain the entire thickness is solid concrete? I thought my ceilings were also concrete, until I drilled into them to install some anchors. After 2-3 cm of cement, there is terra cotta hollow block, which insulates with the air spaces in the hollow block. Find an inconspicuous spot and drill a test hole- you may be surprised.

noma is most probably right about the blocks used... in an old building these would be laid between metal rails and the concrete then poured on top to take the tiled floor...

italian houses are difficult to heat... and its been oft debated here as to ways and means... most discussions seem to end up with the choice of more modern systems and new technology but this means planning ahead before you do any major work to make it a cost effective option...

there are liners you can use and one of these is cork... or there are various plaster board panels with insulation already fitted on one side... these can be fixed directly to ceilings with screws...

two things to consider... make sure that if you do use any material it is very fire safe... and the other is working on ceilings is about the hardest worst job...to do by yourself...

alternative measures to my mind that could increase the feel of warmth... and in reality if you get the ceiling / floors warm they should hold the heat for quite a while... is to back any radiators with reflective foil to move the heat away from the absorbent wall behind it... this should give a good increase in warmth and is cheap and quick to do... the other thing is maybe to increase air circulation either by using a slow fan system or letting air into the house ... this should help to move hot air trapped at your ceiling level to ground level ...it needs careful planning as you can make situations worse or better... but if you have a mobile fan...suggest turning it on in various areas and seeing how it works as regards colder or warmer feeling....

hopefully some of the above will allow you to feel warmer without too much extra cost... and when spring comes you will be able to think in more radical solutions... ie if you havent installed the very best double glazing and shutters and worked on allowing air flows... to stop damp problems... its a good time to plan and cost it now... and get it done before next winter...

building in air gap rooms is also another good idea... ie your most used entrance should have some way of being shut off from the outside and inside so that when you come in with shopping or the dogs need to go out you do not loose all the heat to the outside.... do not seal your house up so tight that air exchange is not possible...especially if you use gas...or even worse bottled / tank gas... these appliances need to have airflow.. especially the heavier bottled gas...

so no really straight answer... its not just your house... if that makes you feel any better... and you are most probably not loosing a huge amount of heat through those areas... you need to look at the house as a whole...including the volume and what amount of heat you are putting in and then make decisions ... based on what you wish to spend on heating costs and what you want to spend to make those costs as small as possible.. as these so0lutions can be expensive its worth getting some good advice on site and or doing a lot of internet research work....

Thanks[/quote]

Theoretically there is not much difference in insulating on any side of the ceiling, so putting any kind of insulation on the loft would be an easy and cost-effective way of keeping the heat in the house. You will need a little longer to heat the house from cold (compared to insulating the underside), as the ceiling itself would need to be heated, but you would then have a heat reserve in the ceiling, to keep the temperature more stable.

Erik

[quote=Erik;107528]...................putting any kind of insulation on the loft would be an easy and cost-effective way of keeping the heat in the house. You will need a little longer to heat the house from cold (compared to insulating the underside), as the ceiling itself would need to be heated, but you would then have a heat reserve in the ceiling, to keep the temperature more stable.

Erik[/quote]

That's what my geometra suggested that I do if I wanted to insulate the house.

I have been thinking about this issue for a while. Surely any energy used to heat up walls, floors and ceiling is essentially not an efficient use? I would not think that concrete or brick is an efficient store of heat. Surely the heat that is released would be much less than the heat that is taken in and secondly the walls etc would not be guaranteed to radiate the heat in the direction that it is required. The heat could be lost upwards or outwards.

I remember someone posting on this site that it took the whole weekend to warm up their stone holiday cottage and ass soon as it was warm they had to leave again.

I would think that the most efficient way is to insulate the inside of any surfaces and keep the heat inside the room space??

[quote=patch2277;107531]I have been thinking about this issue for a while. Surely any energy used to heat up walls, floors and ceiling is essentially not an efficient use? I would not think that concrete or brick is an efficient store of heat. Surely the heat that is released would be much less than the heat that is taken in and secondly the walls etc would not be guaranteed to radiate the heat in the direction that it is required. The heat could be lost upwards or outwards.

I remember someone posting on this site that it took the whole weekend to warm up their stone holiday cottage and ass soon as it was warm they had to leave again.

I would think that the most efficient way is to insulate the inside of any surfaces and keep the heat inside the room space??[/quote]

This is a good point to discuss:

It all depends on how you use your house.
If you use it for short periods, then insulate on the inside. You just have to heat up the air, and keep it warm.

If you live there long term, then insulate outside the massive structure.
This takes longer to heat up, but retains the heat, and results in less boiler input long term.

It also has the advantage that it is cooler in the summer.

I remember someone posting on this site that it took the whole weekend to warm up their stone holiday cottage and ass soon as it was warm they had to leave again.

I would think that the most efficient way is to insulate the inside of any surfaces and keep the heat inside the room space??[/quote]

Yes, theoretically this is the optimal solution, but the difference between them in efficiency is very small. The isolation stops the heat transport from warm to cold areas, and the efficiency of the insulation itself is the same applied on any side of the ceiling, but if you put it on top of the ceiling, some energy will transport through the ceiling and out through the wall - this would be the difference in effiency on either side, provided same insulation is used. Due to the large difference in costs, putting it on the loft is the best solution, unless other factors are counted in (e.g. you need to refurbish the ceiling anyway, you would like to reduce room hight, eastethics, etc).
One thing that can reduse the efficiency when putting the insulation on the loft, is if the loft is to well ventilated, and a steady draught goes through the loft - this can of course be remedied, and would have even bigger value on an uninsulated ceiling. But remember that a minimum of ventilation is needed to avoid humidity, with resulting problems of that.

The point of heating time is of course more important the shorter periods the house is used for, and could be one extra factor in the calculation. If the house is kept warm for longer periods, this would be not be of any importance.

If you are going for weekend stays, having a stone cottage in a cold area, is actually the wrong type of building for the type of use.

Erik

Both Erik and Neil are correct: any insulation will help though in slightly different ways. Having the heat in the concrete is a bit like the masonry stoves you see here in the Alps. Not all the heat is released immediately from the thermal mass of the stove but it certainly doesn't disappear and similarly any heat you generate won't be 'lost in to the concrete' if it's insulated on the outside.

Another aspect I am interested in is which type of ventilation system which would be appropriate. Eventually we would like to build an airtight super insulated house in le Marche at aprox 450m altitude. During August we were on holiday in the same area and stayed in a newish built stone cottage (with rendered interior walls) in the style typical to the region. I am presuming that they had cork insulation in the roof and there was no ceiling.

I was astounded at how much heat the cottage retained. The external temperature was at least 7 degrees lower than the internal despite a window being ajar. No mosquito netting meant we couldn't open it all the way. The rooms were extremely stuffy and apart from the windows there were no other forms of ventilation or air holes. I thought how simple it would be to have a netted air inlet at the bottom of the wall and a extraction fan at the apex of the roof to keep a good airflow going. During winter these could be sealed either by hand or mechanically.

Are there any good ventilation (as opposed to air conditioning ) systems out there or how is this usually handled?

[quote=sueflauto;107539]Both Erik and Neil are correct: any insulation will help though in slightly different ways. Having the heat in the concrete is a bit like the masonry stoves you see here in the Alps. Not all the heat is released immediately from the thermal mass of the stove but it certainly doesn't disappear and similarly any heat you generate won't be 'lost in to the concrete' if it's insulated on the outside.[/quote]

Yes Sue, I understand but my question is if you input 50 Joules of heat into the concrete how many Joules will you get back out? If it is nowhere near 50 then surely this is an inefficient method of energy use?

[quote=patch2277;107542]Yes Sue, I understand but my question is if you input 50 Joules of heat into the concrete how many Joules will you get back out? If it is nowhere near 50 then surely this is an inefficient method of energy use?[/quote]

Energy does not disappear, you will get exactly the same amount out as you put in. The question is in what direction.
Heat energy will move within a given material (in this case concrete) from warm to cold areas, untill the level is the the same all over. If the temperature is lower outside the material (over or under the ceiling - or the wall it is connected to), the energy will transfer on to these areas. Insulation basically keeps small air layers/pockets around what it is insulating, and as air transfers little energy (compared to e.g. water or concrete), and not much energy will go this way. The main "energy leak" will be trough the walls (well, depending on the size of the ceiling, and the amount of insulating on top the ceiling, that is). But again, not so much that it (alone) will justify the extra costs of insulating the underside of the ceiling.

Erik

Insulation is one of the most difficult subjects, as it differs according to house construction, wall types etc. Old stone houses are the worst for heat loss.
We had a analysis on a 300 sq mtr house a couple of years ago, which said it needed 17Kw of heating requirement. With 2cm of wall insulation this would have dropped to 14kw.
If you are having interior walls plastered then insulate them prior to the plastering. Lotan who used to post frequently usually gives the best advice on the subject of insulation issues

[quote=Noma;107515]Are you certain the entire thickness is solid concrete? I thought my ceilings were also concrete, until I drilled into them to install some anchors. After 2-3 cm of cement, there is terra cotta hollow block, which insulates with the air spaces in the hollow block. Find an inconspicuous spot and drill a test hole- you may be surprised.[/quote]

This all makes sense now, when I was fitting a ceiling light in the kitchen, there was a cavity area after drilling through the first bit of concrete, then more concrete.
We've found it takes ages to heat when we visit in the winter but the last owners said it was easy to heat. I should imagine this is because all the heat will remain in the walls etc when it is permanently lived in & kept warm before reaching the winter.

Thanks to everyone for their advice.

Thanks[/quote]

Make it simple for yourselves add 4 cm of polystyrene on the under side of the ceilings and plaster with 2/3 cm of plaster. On the over side add 200mm insulation rockwool in 3 layers the final layer with a wind proof paper to stop any wind pressure surge in the loft space form sucking the heat from the insulation.

All this talk about insulating is rubbish concrete/plaster/rockwool//polstyrene are all non biological products and you don't need any ventilation. To the room yes to the loft above yes but not the ceiling unless there are wooden members actually incorporated in the structure. Anything else is nonsense. Vapour barriers are not needed the 2/3 cm of plaster acts just like one as does the polystyrene.

In a number of investigations it is only the first 2/3/4 cm of plaster that actually can make the absorption and dispersion of calories to the rooms.

Simple!!:yes:

Thanks for the useful discussion. I'm in a similar situation to Dougie and Michelle, and would like to make our heating a bit more efficient. Can I ask a few more details?
The 4cm of polystyrene - is that something you can just buy in sheets from a builders' merchants? Would I need a builder to put it up, or could I just get a plasterer afterwards? How does this compare to the plasterboard with insulated backing, especially in terms of ease of installation and cost? And the rockwool - can you tell me what that is called in Italian?
I'd also love to know if anyone has the stats on the cost effectiveness of these measures. For example, Xm2 of rockwool costs €X, and all else being equal should slow heatloss from a block-and-concrete ceiling by X, which might save around X cubic metres of gas, or around €X a year. Even very rough figures would be useful.
Finally, does anyone know if there are government incentives or tax rebates for this kind of thing?

Don't bother with the incentives it'll take you to 2010 to make the application. Get stuck in and do the loft soonest. It'll keep the house cooler this summer.

You can do it yourself unless your 80 years old in a wheelchair. Polystyrene costs €55/m3 you fix it with plast "tiselli" and you need a plasterer to add the 5 mm reinforced glass fiber matting and then add the 2/3 cm thick plaster. You can do this if you feel you need to after a whole year. :winki: