Underfloor heating (adding to existing build)

DrPhilG

Nearing the end of the process of buying a house and have a query about underfloor heating.

The wife is a cold critter and always wanted to have underfloor heating so with us moving now (and it will be our last move) I thought I'd look into it.

It's a bungalow, approx 1900 square feet. We'll be changing most of the floors (some are damaged, some are just old and grubby). But is it feasable to dig up the floors and lay underfloor heating? What kind of costs would we be looking at? The other alternative is the electric version, but is that expensive to run?

BryanF

DrPhilG wrote: »

Nearing the end of the process of buying a house and have a query about underfloor heating.

The wife is a cold critter and always wanted to have underfloor heating so with us moving now (and it will be our last move) I thought I'd look into it.

It's a bungalow, approx 1900 square feet. We'll be changing most of the floors (some are damaged, some are just old and grubby). But is it feasable to dig up the floors and lay underfloor heating? What kind of costs would we be looking at? The other alternative is the electric version, but is that expensive to run?

1. what is the BER rating?
2. Are the ground floors suspended timber?

UFH can be a serious money pit unless you get the building fabric and UFH / heat supply system correct

imho deal with the building first then the heating system, best of luck

DrPhilG

BryanF wrote: »

1. what is the BER rating?
2. Are the ground floors suspended timber?

UFH can be a serious money pit unless you get the building fabric and UFH / heat supply system correct

imho deal with the building first then the heating system, best of luck

BER is crap at the minute, D, but we plan on getting the loft and wall insulation upgraded to improve that.

Floors are just concrete.

Carlow52

serious mula here as u would have to dig up the concrete floors since u dont know what insulation if any is there all ready.

Putting down elec floor heating without knowing what insulation would be mega foolish and mega expensive

BryanF

Carlow52 wrote: »

serious mula here as u would have to dig up the concrete floors since u dont know what insulation if any is there all ready.

Putting down elec floor heating without knowing what insulation would be mega foolish and mega expensive

aerogel, ufh pipes and screed all on top of existing floor..

DrPhilG

BryanF wrote: »

aerogel, ufh pipes and screed all on top of existing floor..

Doing it on top of existing floors then needs new doors throughout the house though?

DrPhilG

It's a rough idea of cost I'm really after.

If it's going to cost a few grand, I'd do it. If it's going to cost around 5 grand I'd have to think about it. If it's going to cost around 10 grand then it's a definite no!

BryanF

DrPhilG wrote: »

Doing it on top of existing floors then needs new doors throughout the house though?

yes and a lot more besides the doors:)

its the grief/disruption and unknown surprises of digging up the ground floor of a bungalow to lay enough insulation and then install the UFH ssytem...

It's a rough idea of cost I'm really after.
If it's going to cost a few grand, I'd do it. If it's going to cost around 5 grand I'd have to think about it. If it's going to cost around 10 grand then it's a definite no!

are you talking about the 1900sqft or the living room kitchen?

if that's your budget then imho, Id start with an air-tightness test and address air-leakage, then look at putting circa 200mm external wall insulation around the 1900sqft bungalow, from foundations into eaves, overlapped with windows and meeting about 500mm insulation in the attic. then I'd ensure adequate ventilation (be that mechanical or passive stack) and then decide on how to heat the house.

this way you've reduced the demand for heating before you look at how its being delivered..

sas

DrPhilG wrote: »

It's a rough idea of cost I'm really after.

If it's going to cost a few grand, I'd do it. If it's going to cost around 5 grand I'd have to think about it. If it's going to cost around 10 grand then it's a definite no!

It's going to cost alot more than a few grand.

Recent quote for UFH (150m2) materials is 2300+VAT

That doesn't include screed, insulation.

I'd look at other options based on your pricing guidelines above.

DrPhilG

sas wrote: »

It's going to cost alot more than a few grand.

Recent quote for UFH (150m2) materials is 2300+VAT

That doesn't include screed, insulation.

So after some (very) rough calculations I'd be looking at around €3,300 for materials alone?

Then add in the screed and insulation, plus labour for lifting and relaying the floors and the installation of the UFH itself?

We're talking well over the €5k then I take it?

Ddad

At least that. You can add in the cost off all the new and necessary joiney as well.

I priced it on a very similar job to your own and it went out the window. We spent the money on a radiator based replumb back to manifolds with new zoning solar, condensing boiler etc. We're in much the same position with the floor slab with little insulation so we've put in the best underlay we could find for our wooden floors and invested heavily in insulation in the walls and roof. The insulation would have been an incurred cost anyway. Underfloor would have been lovely but as a retrofit it doesn't seem cost effective. Bear in mind that replacing your windows alone will greatly improve the comfort in the house with a lot less disruption and could be done for less than 10k depending on your choices.

DrPhilG

Will be replacing the boiler with a condensing one anyway, as the previous owner removed the boiler when they left (repo).

muffler

DrPhilG wrote: »

We're talking well over the €5k then I take it?

Yes, Id imagine that it would cost well in excess of this. And you wont be able to fit additional insulation without having a knock on effect on your doors and thresholds and associated joinery.

DrPhilG

Looks like the end of the road for that plan then...

Might look into getting the electric version for just the bathroom and the ensuite then. Keep things simple!

Will still be insulating the walls and loft too.

Do-more

Here's a detail for installing under floor heating on top of an uninsulated slab.



Lay 3" X 2' timber joists, 50mm of any high U valve insulation, lay underfloor heating pipe work on top of the insulation and screed 25mm to the top of the joists cover with 18mm chipboard or other structural floor.

Might be worth checking with the technical department of some of the major UFH manufacturers to see what else they would suggest, but as already said the knock on costs are likely to kill your budget.