UFH insulation

[Bungalowben]

Hi - I’ve asked this is another forum but have had limited feedback, so I thought I’d try here.

I have a 1960 built bungalow with solid concrete floors. The floors are covered in asbestos tiles but, once removed (carefully and in line with HSE guidance) the concrete is in good condition and dry.

I’d like to install wet UFH in my kitchen / diner which is approximately 34m2. On a rough calculation I need 18-20k BTU to heat it properly. We have a combi boiler which was installed in 2013 so should be okay for the job.

I’d like to know how best to insulate the floor, whilst minimising build up and to avoid a big step into the lounge. Floor covering will be porcelain tiles.

I appreciate that the two may be mutually exclusive, but in need of some advice.

[ProDave]

100mm of PIR type insulation and a step (and reduction in headroom) or dig up all the concrete and start again.

[scottishjohn]

technically you could use a thin system  and only lift floor level by 50mm -

BUT you will be loosing heat into the concrete without a thick enough layer of insulation 

 a bit of grief now will reduce your heat losses for ever --

do you know for sure that concrete floor has a vapour barrier below it and coming up the sides above the level of the concrete -isolating it  from walls 

probably not at that age --so the right thing is to start again 

 

[Bungalowben]

43 minutes ago, scottishjohn said:

technically you could use a thin system  and only lift floor level by 50mm -

BUT you will be loosing heat into the concrete without a thick enough layer of insulation 

 a bit of grief now will reduce your heat losses for ever --

do you know for sure that concrete floor has a vapour barrier below it and coming up the sides above the level of the concrete -isolating it  from walls 

probably not at that age --so the right thing is to start again 

 

Almost certain it has a vapour barrier under it (2 houses on my street have dug up to lay underfloor properly and had a barrier; all were built at the same time) but it doesn’t lap up.

 

Floor is also bone dry. The kitchen floor and conservatory (which join the dining room) are extensions  and both have vapour barriers which lap up.

 

For the area, had a quote of £7.5k for digging up floor, 100mm celotex and laying UFH in screed.

 

Seem fair/reasonable? Could keep costs down a lot by chopping it up myself, perhaps with rented kango or even a mini JCB type thing?

[nod]

We have a neighbour that has used the same system that John has suggested 50 mil build up 

120m2 I tiled it for him with porcelain plank tiles The same as our own  It heats up and functions just the same as ours 

Ours was laid on 150 insulation and 75 mil screed 

I was really impressed with with the retro fit system and wouldn’t consider digging floors up 

[Bungalowben]

2 minutes ago, nod said:

We have a neighbour that has used the same system that John has suggested 50 mil build up 

120m2 I tiled it for him with porcelain plank tiles The same as our own  It heats up and functions just the same as ours 

Ours was laid on 150 insulation and 75 mil screed 

I was really impressed with with the retro fit system and wouldn’t consider digging floors up 

Interesting - can you explain how the 50mm is made up please?

[nod]

From memory it was interlocking blocks of insulation with grooves in them for the pipes to click flush 

I laid a ditra matting over it and tiled as normal 

All ran to two manifolds 

[Bungalowben]

17 minutes ago, nod said:

From memory it was interlocking blocks of insulation with grooves in them for the pipes to click flush 

I laid a ditra matting over it and tiled as normal 

All ran to two manifolds 

Id like to do 6mm warm-up boards and then the low-profile boards with grooves/insulation.

 

still unsure how it’ll perform though, and the trouble is you won’t know until it’s down, then it’s too late!

[scottishjohn]

3 hours ago, Bungalowben said:

still unsure how it’ll perform though, and the trouble is you won’t know until it’s down, then it’s too late!

It will work fine -just that you will be loosing more heat downwards  than a thicker insulated system --but it will heat room well

 

 

[Onoff]

Check out @oranjeboom's thread. He dug down the whole ground floor. 

 

I did too although in just the one room, the bathroom. Floor brought back level to the adjacent floors.

 

Kangoed the old concrete floor

Dug down by hand

50mm of Type 2 compacted

Sharp sand blind

25mm EPS

DPM

150mm PIR

Polypipe panels with 16mm UFH pipes

100mm wet concrete laid to screed rails

Tanked

8mm ceramic tiles

 

Not yet connected the UFH so it's bloody freezing in there but I'm hopeful!

 

 

[Bungalowben]

1 hour ago, Onoff said:

Check out @oranjeboom's thread. He dug down the whole ground floor. 

 

I did too although in just the one room, the bathroom. Floor brought back level to the adjacent floors.

 

Kangoed the old concrete floor

Dug down by hand

50mm of Type 2 compacted

Sharp sand blind

25mm EPS

DPM

150mm PIR

Polypipe panels with 16mm UFH pipes

100mm wet concrete laid to screed rails

Tanked

8mm ceramic tiles

 

Not yet connected the UFH so it's bloody freezing in there but I'm hopeful!

 

 

Makes sense.

 

What do you mean by tanked?

[Onoff]

2 minutes ago, Bungalowben said:

Makes sense.

 

What do you mean by tanked?

 

It's a wet room so I painted the concrete floor with liquid tanking membrane before I tiled.

[Bungalowben]

31 minutes ago, Onoff said:

 

It's a wet room so I painted the concrete floor with liquid tanking membrane before I tiled.

Ah okay - no need for me to do that for the kitchen/diner/conservatory.

[SiBee]

Hopefully we will be in the same position as you as we have an offer on a bungalow which was built in 1960. Have you looked at Wunda heating? They have retro fit systems. 

Hope the mention is okay as the company has had many mentions on the site?

I have no affiliation, but the system seemed a good idea and I am sure other companies offer the same. 

Ripping out concrete floors is not an option for us so would stick with rads if under floor didn’t work out.

[scottishjohn]

3 minutes ago, SiBee said:

Hopefully we will be in the same position as you as we have an offer on a bungalow which was built in 1960. Have you looked at Wunda heating? They have retro fit systems. 

Hope the mention is okay as the company has had many mentions on the site?

I have no affiliation, but the system seemed a good idea and I am sure other companies offer the same. 

Ripping out concrete floors is not an option for us so would stick with rads if under floor didn’t work out.

ok --but that does not stop all the heat loss into your concrete floor ,

so what ever you do you should think about some sort of insulation beteween you and the foundations .

have no doubts -- the ufh will work but not as good as it could do if you altered the floor and you still free up wall space from having rads 

[oranjeboom]

A lot of companies that sell the retro-stuff sail very close the wind with regards to their suitability for a house with no/or very little insulation. I nearly went down that very path. I've had issues with digging up all my floors and it's delayed things by far. Then had some cowboy anchor screw up the concrete pour - still rectifying the last few rooms now! But the property is a long term home for us, so I didn't want to heating the local moles and went down the more difficult route by adding 300mm+ of EPS under the slab. You may even be better sticking to radiators than going for retrofit UFH.

[SiBee]

Will most likely Stick to rads tbh as I do understand what you guys have said. It’s good to explore the alternatives though as they are out there. I find it fascinating discovers the options and our trades just seem so locked into sticking to what they already know.

The living room we are looking at is two steps below everywhere else, intentionally so. I would want to build this up level so under floor heating would work here To free up wall space.