Digging up slate floor to have underfloor heating?

[t1lly]

Hello, we're in a 70s semi detached. Our hallway, small kitchen, downstairs loo and small office are all slate flooring. i really hate it. It looks ok but its very hard and unforgiving for young people or old people and freezing in winter.

Our kitchen's small and I would like to gain wall space and warmth by getting rid of our wall rad and having underfloor heating with nice funky solid colour vinyl on top. Has anyone dug up to retrofit flooring and have any idea of cost and possible problems? We need a new kitchen anyway so would all be done at the same time. Or do I have to just suck it up and not have underfloor heating and just lay the vinyl on top of the slate tiles? I don't even know if that would work with the floor levels.

Just to add our house has shallow foundations and we're on clay soil (know this from a side extension we had). Thank you.

I’m in the middle of doing this as part of an extension which will be part new house part old very large kitchen/diner/lounge. The old shallow foundations have been taken away, and dug down. It’s so expensive, I really nearly didn’t do it but wanted the underfloor heating as I’m on a mission to warm up my very cold old house.

I happened to have slate tiles in the old kitchen, they removed them, found another level of tiles then the old wooden floorboards.
once it’s all dug out they put insulation down, pour a concrete slab on top then more insulation then the pipes and screed and finally you can get the flooring (not there yet).

its a lot of work and very expensive but I’m hoping worth it for a warm is room afterwards and I have to do it now or never…

Wow. That sounds like it will be fantastic. And such peace of mind to have proper foundations! (I just try to not think about the fact our house seems to be balanced on a few inches of concrete 😱). I would love to do that but seems unaffordable I think for our little house. I do worry that digging up the floor might destabilise things.
I think budget is probably going to mean underfloor heating is out, but even just digging up the tiles seems a big job...

Yes we have retrofitted UFH but not with a slate floor. We drilled out the existing concrete slab, layer insulation then UFH, porcelain tiles on top. An older part of the house had joists so we managed to lay UFH between them after insulating.

it was a long and hard job. The dust was insane from the drilling. Cost us £30k but well worth it now for a warm house with the flooring we wanted

Digging up floors, putting in modern style upvc, removing fireplaces - it’s how a lot of older houses lost their charm and functionality.

You will have to dig on hell of a way down. You will need enough insulation plus a minimum 50 mm screed on top. Having watched mine done in a new extension build it is very difficult to retrofit a genuine water based UFH system

Its a 70s semi, and it's just modern slate tiles put down by the previous owners. But I've lived in a Victorian terrace with sash windows and fireplaces and quarry tile floors and completely agree with you on that front.
I will have to replace the flooring at some point, but sounds like underfloor heating is probably going to be a no-go.

Sounds fantastic. That kind of sum would put it out of budget for us. I will have to investigate just laying new flooring on top of the tiles I think!

When we had our extension done we took the UFH through to older parts of the house and it was laid on top of the floorboards.

They used a type of polystyrene tray that the pipes sit in and a thi screed over that.

It means that we have a small step down to our lounge which is carpeted but it works just fine.
All of the skirting boards had to be re done.

It was expensive but so worth it. It's a different type of heat and has made the house so much more liveable.

See if the builder can do it on top of the existing ?

I did think about that. I am not sure the step down to the lounge would work for us but it's worth considering, you're right. Got to redo the skirting boards anyway whatever we do as they are slate sort upstand things. thanks

What a bizarre comment! What would you suggest? That the OP just uses a fireplace for heat, uses candles for lighting, sleeps under newspapers for warmth and washes clothes by hand then uses a mangle to keep the charm! 🙄

OP- We have just finished a massive renovation, which also included UFH. It was a whole house renovation, so I don't know the costing for just the UFH though. We had a mix of floorings- wood and concrete from various extensions that had previously been added. We are on clay also and ours is 1930's.

At the time, we had no windows or doors, and they brought in a mini digger to lift the flooring and dig down. They discovered that the utility floor was floating, and not connected to the rest of the house! On massive benefit of digging it all up, was they were able to even out the flooring to one level. Previously, there was a small step into the utility and from the front entrance.

I was surprised how deep they dug down, but there were many layers which went on top. We weren't living in the house at the time. The whole ground floor was just clay for a period of time, so consider if you'd need to set up a kitchen elsewhere whilst the works are being done (assuming you'd still be living there?)

Hello, I have a similar situation. I’ve found a company that makes a heated pad that goes underneath a rug, I don’t know if that would work?
I was looking for a bathroom mat I could heat, maybe battery operated?if anyone knows of such a thing?
anyway here’s the rug thing. Haven’t bought one yet, but it looks ok and I imagine it oils be nice underneath runners and rugs (dunelm have some nice washable ones)
https://www.bewarmer.co.uk/rugbuddy-faqs/#FAQ7

I would just add a floor on top with insulation.

For click LVT the floor needs to be level otherwise it puts stress on the joints and the floor can break up. Another issue with click lVT is that the insulation layer cannot normally be that thick, because a thick layer compresses more and causes movements in the joints.

I would probably go for some type of flooring that allows thicker insulation and upgrade the wall radiators for much lower cost.

A couple of points.

Underfloor heating does add some height, so could be an issue with existing doorways/doors needing re-hanging or shortening. Other than that, I don't see any difficulties with installation.

My parents' house of 40 years had underfloor heating across the entire spacious ground floor and it was marvelous. This was with a tile flooring on top btw - tiles are not classy and uncomfortable at all once they're nice and warm and they retain the heat very well. Since you mentioned "funky solid colour" vinyl, I'd also investigate linoleum in that case. Quality and design has improved enormously, especially if you're looking for funky. Also neither vinyl nor plinoleum typically need a completely level floor, they're very forgiving. (I should know - I'm in an old house with a couple of inches slope, and it was either vinyl/lino or rebuild the entire floor!)

Re cost, obviously removing old flooring and installing system won't be cheap. But if you're ever thinking of installing a heat pump underfloor heating hugely reduces your running costs.

If by vinyl you mean click vinyl the floor has to be level.

But, there is level and level. For example if the floor slopes like you describe from one side of a room to another, between tiles it is actually quite level, just unlevel when you take the whole floor into account. This would probably be OK.

The problem would be when it changes from being level over a length scale comparible to the tiles. For example in my kitchen there are gaps in the grout, so if a click tile lines up with the grout gaps, its a problem (I spaced them so it wouldn't). Also if your tiles have a "rustic" effect and there is a significant difference in height between individual tiles then that is also a no-no and the floor needs levelling out in some way.