(C)old stone cottage- orig floor insulate?

[zoothorn]

Hi chaps, happy new year.

 

I have a C1830 small welsh stone cottage with terrible cold issue, coming up from old floor for definite. Its a stone 2ft thick, 4-walled original 'shell' (so 1 big main room) with an 80's 1st floor addition (2 small beds) plus small ground-floor kitchen/ b'room extention.

 

Main room floor: my builder did see a bit of blue dpm edge 'evidence', so maybe not original floor: but I'm certain there's no insulation as its SO cold underfoot. So is the right idea to dig & put in PIR? And could it be done in 'halves'? (say a placcy screen for dust, shifting stuff over > do one side at a time?).

 

I do have minor damp patches twds edges too.. so dpm either badly done or compromised would you think?

 

Your thoughts appreciated.

 

Zoot

 

 

Edited January 3, 2019 by zoothorn

[Ferdinand]

On 03/01/2019 at 11:26, zoothorn said:

Hi chaps, happy new year.

 

I have a C1830 small welsh stone cottage with terrible cold issue, coming up from old floor for definite. Its a stone 2ft thick, 4-walled original 'shell' (so 1 big main room) with an 80's 1st floor addition (2 small beds) plus small ground-floor kitchen/ b'room extention.

 

Main room floor: my builder did see a bit of blue dpm edge 'evidence', so maybe not original floor: but I'm certain there's no insulation as its SO cold underfoot. So is the right idea to dig & put in PIR? And could it be done in 'halves'? (say a placcy screen for dust, shifting stuff over > do one side at a time?).

 

I do have minor damp patches twds edges too.. so dpm either badly done or compromised would you think?

 

Your thoughts appreciated.

 

Zoot

 

 

 

HNY Zoot.

 

Tell us about your floor.

 

 How do the levels and heights work?  Can you go upwards instead of digging?

 

F

[Onoff]

BEFORE you have the lino done!

 

My own kitchen might have some parallels. Pic shows it taken from outside with the phone stuffed through the fan light. SWMBO's fo'd to Bluewater or somewhere. Nice to come home to it all tidy! 

 



 

I have no heating in the kitchen. It is 'kin cold. Even been known to leave the oven door open to warm the place up. The kitchen is a years ago add on. Concrete floor. The oddity is that the concrete floor is just a solid 5" slab cast over the ORIGINAL concrete floor. I could likley Kango it up and gain 5" in room height. The readon for this we think is that without it there would have been a 1' step down from the boiler room to the kitchen floor. So from outside you step up into the boiler room. Then one step down into the kitchen, then step down into the rest of the house...

 

I've discussed on here previously about digging down a bfo rectangle in the kitchen floor. Then heavily insulating underneath (& sides) and concreting back up with UFH pipes in. It has some merit.

[Onoff]

Can be done & cheaper than gym membership!

 

1) The bathroom had a concrete floor some 60mm higher than the adjacent rooms. It was in fact pretty much dead level with the DPC (damp proof course). That was slate on the two original solid brick walls and some sort of bitumen felt on the two cavity walls:

 

 

 

2) Not the only room in the house with level issues. So out with the BiL's vintage Kango:

 

 

 

 

3) I bagged it and hand balled it out the front door. About 80 bags from memory:

 

 

4) Got down to top soil:

 

 

5) And started to DIG! Someone worked out the tonnage that I shifted, again by hand. 7 tonnes? Can't remember though I did lose weight!

 

 

6) Hit our wonderful clay not too far down:

 

 

7) So then to build it back up. I didn't now how but knew I wanted UFH. Started the questions on eBuild!

 

So I banged a load of level pegs into the clay allowing 2 - 4". Tbh nearer to 2" in most areas. Sprayed the pegs so I could see them:

 

 

? First off I graded a load of the hard core that came out of the floor thru a 40mm mesh sieve. Basically I'm too tight to buy Type 2 etc. Laid it roughly level:

 

 

9) Somewhere around this point I shuttered off and squared up, with concrete, the ragged tops of the footings:

 

 

10) Any old bags of cement, plaster etc got thrown in to help get rid of it and fill voids in the hard core:

 

 

11) I then bought a second hand electric wacker plate and compacted it all down.

 

(Did take a slight diversion and started making an electric wacker plate. THAT story is to be continued!  )

 

It WILL live one day!

 

 

 

12) Anyway.....back on thread. Wacking:

 

 

13) Sharp sand went down next to fill all the voids. Me being me it was all levelled off:

 

 

14) At this point I was feeling pretty happy, I mean it just looks FINISHED!

 

 

15) 25mm of EPS went down next. EPS doesn't suck up water like PIR can so can be in direct contact with damp "ground". It's why so many here put 300mm of EPS under their concrete slab under the whole house. The combo of the sharp sand and EPS is to ensure no sharp bits of hardcore poke up thru the DPM (damp proof membrane). Think the sand and deffo the 25mm EPS was @Nickfromwales idea.

 

 

16) I'll openly admit I went full @pocster and had a sneaky, naked lie down on it at this point. It felt SO WARM!  

 

 

17) I continued the EPS over the squared off footings and up the walls a little as a nod to cold bridging. Glued on with Soudal Low Expansion Foam, thanks to @JSHarris for that tip. You can see where the damp is coming thru:

 

 

18) Probably OTT but I applied a liquid DPM up to the level of the DPC. 

 

 

19) Whilst the second coat was wet I blinded it with sand to give something for the Soudal foam to key to and when dry foamed the EPS in place. 

 

 

20) Thick, blue DPM next. From Screwfix, on a roll:

 

 

21) Bit of a pig folding it into the corners:

 

 

22) Next 150mm of PIR as a 50 and 100 layer. Better to put the 50 down first the the 100 - wish I had!  I'd suggest 150mm as a minimum. With hindsight I'd have dug a bit deeper and gone 200mm:

 

 

 

23) The DPM carries on up the wall with the intent of sticking to / overlapping the vcl on the stud walls to come. It's why the room is so draught free. 

 

 

24) Now at this point I could have laid a plastic membrane over the foil faced PIR and stapled my UFH pipes down.....I didn't. Instead I used Polypanels as I think suggested by @PeterW. They serve 2 purposes; to act as a separating membrane between foil face and screed or concrete (you can get a reaction) and also to aid laying the UFH pipe. They also save a bitbon concrete:

 

 

25) I used a self adhesive edging strip, basically a corrugated cardboard/EPS sandwich. This takes up any expansion of the slab as it heats up.....or it can push against your walls! Probably overkill as I've already the ESP upstand:

 

 

26) With my homemade pipe decoiler it makes laying it a breeze as the video shows:

 

 

27) A142 reinforcing mesh was laid next as per @JSHarris's build / suggestion. Probably the only thing the houses share in common!

 

I attached screeding rails (Unistrut) to the stud walls which were only affixed at this point to the walls and ceiling. A drag board went between. It's the reason my slab is so level:

 

 

27) A strong., wet concrete mix went down to give me a 100mm slab. Pockets left for the wet room tray which I cast later and one to "sink" the bath a bit:

 

 

 

Et voila:

 

 

From top of the original concrete I dug down a minimum of 385mm.

 

Final, conservative floor build up was:

 

- 50mm compacted Type 2 on clay

- Sharp sand blind

- 25mm EPS

- 1200 gauge DPM

- 150mm PIR (100 + 50)

- Polypipe panels

- A142 mesh

- 100mm concrete (though I forgot to add the fibres  ).

- Ceramic tiles

 

 

@oranjeboom has done similar to his WHOLE HOUSE. Tbh that's my plan eventually.

Edited January 4, 2019 by Onoff

[newhome]

It doesn't help with the overall house issue but when my heating broke down in the winter it was damn cold in here and I found that it was pointless trying to heat the whole room up with a poxy little electric heater so as I was here by myself I concentrated on heating me and not the room. To that end I bought a heated throw such as this one 

 

https://www.amazon.co.uk/MP-Essentials-Fleeced-Blanket-Settings/dp/B07B9N1WVD/ref=sr_1_3?ie=UTF8&qid=1546624457&sr=8-3&keywords=heated%2Bthrow&th=1

 

Peanuts to run but made life bearable until I got the heating fixed. Maybe you should consider doing the same until you get your insulation sorted. 

 

Good for folk braving caravan life over the winter too. 

 

[newhome]

3 minutes ago, Onoff said:

Can be done & cheaper than gym membership!

 

 

Jeez was that the bathroom? How deep and what insulation did you put in? Electric or wet UFH? 

 

[zoothorn]

39 minutes ago, Ferdinand said:

 

HNY Zoot.

 

Tell us about your floor.

 

 How do the levels and heights work?  Can you go upwards instead of digging?

 

F

 Hi Ferdinand.

 

Good Q- alas cannot add onto/ up. Its the lowest ceiling Ive ever known in a house perhaps (& would add a badly out of kilter step). Imagine a characterful black & white beamed cottage ceiling.. then take a foot+ off! It must be to same level, which continues thru to adjoining kitchen.

 

 

[zoothorn]

@Onoff wow you've even done this very job! & your results- really 1st class (pic3). Assuming your idea's as mine, to essentially put in 100mm of PIR underfoot.. any info/ pics between pics above 2 & 3?

 

I thought it might be a jackhammer affair. Ok one imperative consideration/ difference with mine, is some vertical beams bases of which of course sit upon (or upon what exactly?) the floor as is: IE if I take these away.. I can't bear to think, but Laurel & Hardy springs to mind.

 

 

[zoothorn]

55 minutes ago, newhome said:

.. Good for folk braving caravan life over the winter too. 

 

 Hi newhome- very kind link/ good plan I admit. I resort to warming hands over toaster s'times.. last did this as a 19yr old stewdent-grant. This cold snap I'm just going full pelt on my 1 'leccy slim kitchen rad (I had a similar one 2x as big, in main room.. but just removed/ sold it bc putting it on didn't make a jot of difference/ total waste of £ & energy, any heat if felt just going up stairway above).. & my stove stuffed to the gills for my 2 hr 'window' 7-9pm.

 

A leccy blanket- now you remind me- is a must next-thing to get.

[Onoff]

1 hour ago, zoothorn said:

@Onoff wow you've even done this very job! & your results- really 1st class (pic3). Assuming your idea's as mine, to essentially put in 100mm of PIR underfoot.. any info/ pics between pics above 2 & 3?

 

I thought it might be a jackhammer affair. Ok one imperative consideration/ difference with mine, is some vertical beams bases of which of course sit upon (or upon what exactly?) the floor as is: IE if I take these away.. I can't bear to think, but Laurel & Hardy springs to mind.

 

 

 

I'll edit the post and add detail of all the stages I can think of. Tbh the build up is down to the input of all the good folk on here. I'll namedrop where I can, apologies if I credit the wrong people or forget someone!

[zoothorn]

This is the basic house, foreground the 80's dreadful kitchen, behind the 4-thick-walled 'shell' main room (ontop the 80's disaster 1st floor addition).

[Ed Davies]

Any idea what the ground water under and around the kitchen does? What I'm wondering is if there's any possibility of perimeter insulation doing any good. The slope down on the left seems like good news from this point of view. The slope up on the right, less so.

 

Edit to add: the slope down on the left would at least make drainage of any insulation easier.

Edited January 4, 2019 by Ed Davies

[zoothorn]

Another good Q Ed- yes 2 slopes, LHS drains away acroos then steeply down to brook 5m from house. RHS: water collects along this channel here, but nothing Ive ever been concerned with & main WC drain in middle helps. If damp ingress via this RHS channel here you might be thinking, nothing to say inside the main room this side any different/ worse than other LHS. Seems ok.

[Onoff]

My post edited with lots more details.

[Ferdinand]

11 hours ago, Onoff said:

My post edited with lots more details.

 

if I did a post like that, it would be a telltale that there was something useful I was avoiding doing.

 

Good posts.

 

@zoothorn take a look at doing perimeter insulation a la Ed ... may be worth thinking about, but you would need to perhaps combine with some sort of thought through floor covering to give a warmer feel. Cork tiles might do it, or some sort of cushion floor, or a minimal thickness floating floor which would feel warm even though that on its own would not fix your insulation issue, 25mm pir and laminate click-fit would do that.

 

Your issue with perimeter insulation may be that there could be no or minimal foundations, so it will risk destabilising something. If so, digging up internally would be better as perimeter insulation will need to be perhaps twice as deep.

 

On the height ... just to check. Do you have exposed beams, or are they actually covered over with eg plasterboard. If still covered, removing the boarding and reverting g to a beamed ceiling would perhaps help the ‘feel’ of the room.

 

My former cottage was 7’4” between beams AFTER the ceiling boarding had been removed, with the central beam being about 6’6”. It is now rented to a short tenant.

 

F

Edited January 5, 2019 by Ferdinand

[Onoff]

1 hour ago, Ferdinand said:

It is now rented to a short tenant.

 

Is he happy, grumpy etc?

 

 

 

[Onoff]

Seriously now is there any benefit in excavating a neatish, big hole in the floor, say 300 - 400mm deep. 150 - 200mm of PIR in the base, 50mm PIR round the sides. Wet concrete slab with a UFH loop in it. Obviously a channel cut in the floor to a manifold.

 

???

[oldkettle]

I want to carefully ask whether anybody actually notified BC about this kind of a job. What are the risks of not notifying in case of a floor slab where there is not really much chance of anybody noticing?

[newhome]

26 minutes ago, oldkettle said:

I want to carefully ask whether anybody actually notified BC about this kind of a job. What are the risks of not notifying in case of a floor slab where there is not really much chance of anybody noticing?

 

How would they find out unless someone approached them and told them? It's not like this would likely be noted in a future survey unless the surveyor KNEW that the floor had been dug up and insulation added recently. Assuming that whatever is covering the floor now (carpet?) covers the floor afterwards I don't see how they could ever know. BC would just take money off you for the privilege of trying to do the right thing and upgrade insulation. 

[zoothorn]

@Onoff hey thanks for all the info-  impressive.. & terrifying in equal measures. I had no idea the job was to this level of xyz to do. Maybe I can simplify / hope so or its too daunting a job.

 

My crib before was just a small new [pro] built 'wing' (onto an old cottage). Took tons of pics of build (lost on a died laptop- v. annoying) & seem to recall the floor wasn't nearly as complex, & 'felt' perfectly good/ normally-well insulated: once the base prepped it seemed to be effectively, a dpc > eps only (poss 100mm?) > concrete top, levelled, then hand smoothed over with a big square float.

 

I was hoping I could do it in a roughly similar way, the digging down/ removal & prep being the vast majority of the work. I'll have to consider possibility of hitting stone (slate- not too hard I believe, thankfully).. how much I hit dependent I guess on what depth to go down.

 

What would be the minimum insulation I should be considering here? I'll not be going whole hog 300mm thats for sure.

[zoothorn]

@Ferdinand can you explain perimeter insulation.. are you talking walls, externally? Im not entertaining this idea if so, as it'll detract from the contoured original exterior. The orig 'shell' 4 walls are are undoubtadly cold slate lumps sure.. but will have to be, & everything but the kitchen sink addressed/ attacked but them: that's the basic action plan for the house.

[Ed Davies]

Perimeter insulation goes downwards round the outside of the house, maybe a metre or more into the ground. The idea is that heat doesn't escape from under the floor sideways. So long as water isn't flowing, even very slowly, through the soil under the house it should give you a warmer ground reducing your heat losses downwards a lot - once that soil  has warmed up.

 

Sometimes it's done vertically down the outside of the foundations. On older houses without foundations it probably needs to slope outwards so was not to undermine the walls.

 

A question with your extension would be whether you go the whole way round the house or what?

[A_L]

Assuming a  8m x4m floor slab it currently has a U-value = 0.89. Vertical edge insulation (EPS lambda 0.036 W/m.K), down the inside or outside of a foundation wall  gives depth/U=values 0.5m/0.62, 0.75m/0.55 and 1.0m/0.50. thicker/deeper insulation has relatively little additional effect.

 

A 100mm of PIR with no edge insulation would give a U-value = 0.18

 

At the the moment  the cold floor effect can only be mitigated by using a floor covering with a low thermal conductivity as you have a massive thermal cold store in the floor..

Edited January 5, 2019 by A_L
to add "(EPS lambda 0.036 W/m.K)"

[Onoff]

25 minutes ago, A_L said:

At the the moment  the cold floor effect can only be mitigated by using a floor covering with a low thermal conductivity as you have a massive thermal cold store in the floor..

 

So would an inset, insulated, heated block of concrete as a thermal store mitigate some of that?

[Onoff]

2 hours ago, zoothorn said:

Took tons of pics of build (lost on a died laptop- v. annoying)

 

How did it die? Did you try the hdd in a USB caddy?