Ground Floor Makeup

BarneyMc · 21-08-2015 5:52pm #1

Trying to decide on how my ground floor should be built up. From the slab (sub floor I think it's called) to the bottom of my external doors is 250mm.

Liquid Screed Option
External door gap 5mm
Tile/laminated floor 15mm
Liquid screed 50mm
Floor insulation (PIR) 180mm

Sand/cement Option
External door gap 10mm
Tile/laminated floor 15mm
Sand/cement 75mm
Floor insulation (PIR) 150mm

Liquid screed option looks good regarding insulation levels but I'm not sure 5mm is enough to leave for a gap for external doors. Maybe reduce the insulation to 160mm and have a 15mm gap?

Sand/cement option gives me a sand/cement floor which might work best with UFH and HP but leaves me a bit shy with the insulation.

What's my best bet?

Calahonda52 · 21-08-2015 5:55pm

Not finished yet then:D

I don't know the answer but is 50 mm liquid screed enough on PIR?

delfagio · 21-08-2015 6:58pm

Calahonda52 wrote:

I don't know the answer but is 50 mm liquid screed enough on PIR?

Hi Calahonda, is there a reason why would 50mm not be enough on PIR?? I have 45-50mm on ground floor and 50-55mm on 1st floor on PIR.

Just on your options Barney. Again I'm sure with your underfloor heating you are beating the 0.15 U-Value in the Regs. I suppose there gets to a point when adding more insulation becomes no more beneficial from a monetary point of view. Getting bang for your buck as the saying goes.

Say 160mm PIR insulation might be getting you I don't know, say 0.11 U-Value in your floor. Then spending the extra money, which may be quite a bit, on 180mm PIR insulation to get a U-Value of 0.10, for the fraction extra in U-Value is pointless. Don't get me wrong, if that's what you want to get, by all means go ahead but in the reality of living in the house your not going to notice that 0.01 of a difference in the U-Value....if you get me.

So if it were me, I'd go with the 160mm option if this is beating the 0.15 U-Value requirement for UFH in the regs and get the 15mm door clearance. Plus that 15mm gives you the option in the future if you decided you wanted to change the floor tiles to a thicker one. If you leave yourself short of door clearance now you limit your options in the future for changing.

I had a similar decision to make and went with the extra clearance at doors as I was getting 0.11U Value in floor

BarneyMc · 21-08-2015 7:27pm

Calahonda52 wrote: »

Not finished yet then:D

I don't know the answer but is 50 mm liquid screed enough on PIR?

As far as I know yes, it is.

BarneyMc · 21-08-2015 7:30pm

delfagio wrote: »

Hi Calahonda, is there a reason why would 50mm not be enough on PIR?? I have 45-50mm on ground floor and 50-55mm on 1st floor on PIR.

Just on your options Barney. Again I'm sure with your underfloor heating you are beating the 0.15 U-Value in the Regs. I suppose there gets to a point when adding more insulation becomes no more beneficial from a monetary point of view. Getting bang for your buck as the saying goes.

Say 160mm PIR insulation might be getting you I don't know, say 0.11 U-Value in your floor. Then spending the extra money, which may be quite a bit, on 180mm PIR insulation to get a U-Value of 0.10, for the fraction extra in U-Value is pointless. Don't get me wrong, if that's what you want to get, by all means go ahead but in the reality of living in the house your not going to notice that 0.01 of a difference in the U-Value....if you get me.

So if it were me, I'd go with the 160mm option if this is beating the 0.15 U-Value requirement for UFH in the regs and get the 15mm door clearance. Plus that 15mm gives you the option in the future if you decided you wanted to change the floor tiles to a thicker one. If you leave yourself short of door clearance now you limit your options in the future for changing.

I had a similar decision to make and went with the extra clearance at doors as I was getting 0.11U Value in floor

Spot on the the U values! 150mm is getting me 0.12 and 160 is getting me 0.11. Your reasoning seems good - very grounded!

delfagio · 21-08-2015 9:10pm

BarneyMc wrote:

Spot on the the U values! 150mm is getting me 0.12 and 160 is getting me 0.11. Your reasoning seems good - very grounded!

Yea that's how we made the decision when we were faced with it. It made sense to me to give me that additional clearance at the doors, but it absolutely wrecked my head for days until we made a definite decision, thinking of all possible scenarios....even something as simple as a mat inside the doors to wipe your feet. Leaving only 5mm clearance just wasn't much to allow a decent floor mat to be inside the door without the door rubbing/catching on it and pushing it out of the way every time the door opened so we made the decision to lower the insulation slightly to give us the extra clearance at the doors. As I said the option to change floor covering in the future say if we were to change to a good thick solid wood floor or thicker tiles will be there for us even if we never change. The fraction of the U-Value that was in the difference meant we decided to decrease the insulation in the floor and still get good U-Value.

There's so many simple, even sometimes the smallest but seem like the biggest decisions that you have to make during a build that you wouldn't even think about normally, but when they pop up during construction......it's like the bloody world is coming to an end and feels like your brain is going to explode trying to think of every possible outcome due to whatever decision you go with. You stress for days over it, then once the decision is made its like....."Yea sure that's great, I'm happy with that"......then two weeks later something else pops up, and your like "NOOOooooo why does this house hate me"....Ha ha oh the joys of it all

BarneyMc · 21-08-2015 11:03pm

delfagio wrote: »

Yea that's how we made the decision when we were faced with it. It made sense to me to give me that additional clearance at the doors, but it absolutely wrecked my head for days until we made a definite decision, thinking of all possible scenarios....even something as simple as a mat inside the doors to wipe your feet. Leaving only 5mm clearance just wasn't much to allow a decent floor mat to be inside the door without the door rubbing/catching on it and pushing it out of the way every time the door opened so we made the decision to lower the insulation slightly to give us the extra clearance at the doors. As I said the option to change floor covering in the future say if we were to change to a good thick solid wood floor or thicker tiles will be there for us even if we never change. The fraction of the U-Value that was in the difference meant we decided to decrease the insulation in the floor and still get good U-Value.

There's so many simple, even sometimes the smallest but seem like the biggest decisions that you have to make during a build that you wouldn't even think about normally, but when they pop up during construction......it's like the bloody world is coming to an end and feels like your brain is going to explode trying to think of every possible outcome due to whatever decision you go with. You stress for days over it, then once the decision is made its like....."Yea sure that's great, I'm happy with that"......then two weeks later something else pops up, and your like "NOOOooooo why does this house hate me"....Ha ha oh the joys of it all

I totally understand! I've got to the stage where I try and not get too caught up with U values, etc. and think of practical issues - like the mat! :rolleyes:

delfagio · 21-08-2015 11:36pm

BarneyMc wrote:

I totally understand! I've got to the stage where I try and not get too caught up with U values, etc. and think of practical issues - like the mat!

It should be called "Stress Build" and not "Self Build".

Just looking at your floor make up again there, if you go with 50mm liquid screed option with a 15mm floor covering and 15mm clearance under doors this actually leaves you with 170mm left for floor insulation not 160mm. Little extra insulation in floors you could do.

BarneyMc · 21-08-2015 11:55pm

delfagio wrote: »

It should be called "Stress Build" and not "Self Build".

Just looking at your floor make up again there, if you go with 50mm liquid screed option with a 15mm floor covering and 15mm clearance under doors this actually leaves you with 170mm left for floor insulation not 160mm. Little extra insulation in floors you could do.

Yes, could do alright but would mean using 2 different PIR boards, e.g. 80mm + 90mm but I suppose that's not a major issue really.

delfagio · 22-08-2015 7:26am

BarneyMc wrote:

Yes, could do alright but would mean using 2 different PIR boards, e.g. 80mm + 90mm but I suppose that's not a major issue really.

No major issue there. I used 50mm PIR boards on the 1st layer then 100mm PIR boards on 2nd layer.

Calahonda52 · 22-08-2015 8:28am

The reason I wrote this is that I that I don't know

Calahonda52 wrote: »

I don't know the answer but is 50 mm liquid screed enough on PIR?

What I expected was that the manufacturer of either the screed or the UHF would tell you that X mm was required, depending on the actual subfloor make up.

delfagio · 22-08-2015 9:22am

Calahonda52 wrote:

What I expected was that the manufacturer of either the screed or the UHF would tell you that X mm was required, depending on the actual subfloor make up.

Ah that's ok, I thought you meant 50mm wasn't enough.

Generally the liquid screed manufacturer/companies say with liquid screed you only need a minimum of 25-30mm cover over the UFH pipes which are 16mm typically, so this totals 40-45mm depth and usually 50mm is what is installed.

Don't quote me on this but as far as I am aware the liquid screed is actually stronger in compressive strength than sand/cement screed, and this is why it can be laid at thinner depths than sand/cement

Calahonda52 · 23-08-2015 11:12am

delfagio wrote: »

Ah that's ok, I thought you meant 50mm wasn't enough.

Generally the liquid screed manufacturer/companies say with liquid screed you only need a minimum of 25-30mm cover over the UFH pipes which are 16mm typically, so this totals 40-45mm depth and usually 50mm is what is installed.

Don't quote me on this but as far as I am aware the liquid screed is actually stronger in compressive strength than sand/cement screed, and this is why it can be laid at thinner depths than sand/cement

All I am trying to get at is that folk who come after will read this and ask the question, will it work, at X mm on Y mm of PIR.

delfagio · 23-08-2015 11:36am

Calahonda52 wrote:

All I am trying to get at is that folk who come after will read this and ask the question, will it work, at X mm on Y mm of PIR.

Yea very true, good point.

It's strange walking on the liquid screed for the first time. I had thought it would be solid, but it has a floating floor sensation to it, obviously as it is sitting on top of 150mm of PIR. If you knock it with your hand it echos through the floor, or if you give a little stamp of the foot on it, you feel the vibration through the floor.

But as I said it is recommended by all liquid screed companies that 50mm depth is adequate regardless of the depth of insulation underneath.

PROJECT K · 24-08-2015 3:23pm

Hi barney, I am facing a similar issue, exacerbated by doors installed at slightly incorrect levels! You mention clearance under the front door, I presume this is to the bottom of the door leaf? Just bear in mind that you must have no more than 15mm threshold for accessibility under Part M and this will dictate local floor level (assuming you are using front door as main access). Can be an issue with a lot of doors whereby the bottom of the door leaf sits almost 10mm below door frame threshold - leaving just 5mm to finished floor. You can also 'ramp up' to the door locally (max 15deg) if required.

In relation to the floor mat I am going to form a recess in the floor tiles for a 'sunken mat' so that it doesn't interfere with door opening...also less chance of old people (me by the time my house is finished!) tripping on the mat!

BarneyMc · 24-08-2015 8:54pm

PROJECT K wrote: »

Hi barney, I am facing a similar issue, exacerbated by doors installed at slightly incorrect levels! You mention clearance under the front door, I presume this is to the bottom of the door leaf?

Yes, by clearance I mean from the very bottom of the door down to the tiles/wooden floor.

PROJECT K wrote: »

Just bear in mind that you must have no more than 15mm threshold for accessibility under Part M and this will dictate local floor level (assuming you are using front door as main access). Can be an issue with a lot of doors whereby the bottom of the door leaf sits almost 10mm below door frame threshold - leaving just 5mm to finished floor. You can also 'ramp up' to the door locally (max 15deg) if required.

Thanks, wasn't aware of this. Adds another angle to things but will check to see how this will work for me.

PROJECT K wrote: »

In relation to the floor mat I am going to form a recess in the floor tiles for a 'sunken mat' so that it doesn't interfere with door opening...also less chance of old people (me by the time my house is finished!) tripping on the mat!

Now this is something I thought about and dismissed but would be a great job in my opinion. How do you get a recess into the floor tiles? Do you leave a recess in the floor itself and if so then is it ok to sink the thickness of the screed down here? Also what dimensions do you leave for a 'generic mat'.

PROJECT K · 25-08-2015 9:43am

BarneyMc wrote: »

Now this is something I thought about and dismissed but would be a great job in my opinion. How do you get a recess into the floor tiles? Do you leave a recess in the floor itself and if so then is it ok to sink the thickness of the screed down here? Also what dimensions do you leave for a 'generic mat'.

Two schools of thought on this - yes its very convenient but some might say a bit 'commercial' looking. I have seen it done and when its done well, it looks fine to me. I plan to just not tile a rectangular area (size to be determined) and use a nice tile trim around the 15mm deep 'opening'. then trim a suitable mat to fit in the recess - don't think theres any such thing as a standard sized floor mat but will have a look around before I finalise the opening size. I was planning to do something similar in the utility area anyway (mat inside and grating outside - to get rid of all those stones before they scratch the floor tiles!):eek:

ht9zni1gs28crp · 25-08-2015 10:19am

With regards to the mattwell. Coir matting comes in different thickness. 15mm 18mm 21mm. Any size to suit as its carpet like rolled form in the shop.

We were advised not to sink the slab, use the 15mm Coir matt into the 13mm space created by the floor tiles. The 2mm is not noticeable and the coir flattens slightly over time. Use some nice tile edging to close off the tile and that's it. The coir matting is heavy enough that it wont move within this recess.

On a side note, make sure the Mattwell extends well beyond the width of the door opening, ours is nearly the same width again and works a treat for people stepping in.

BarneyMc · 25-08-2015 10:28am

miller_63 wrote: »

With regards to the mattwell. Coir matting comes in different thickness. 15mm 18mm 21mm. Any size to suit as its carpet like rolled form in the shop.

We were advised not to sink the slab, use the 15mm Coir matt into the 13mm space created by the floor tiles. The 2mm is not noticeable and the coir flattens slightly over time. Use some nice tile edging to close off the tile and that's it. The coir matting is heavy enough that it wont move within this recess.

On a side note, make sure the Mattwell extends well beyond the width of the door opening, ours is nearly the same width again and works a treat for people stepping in.

Sounds fantastic and more floor depth to play with! Can I be cheeky and ask for a photo or 3? :pac:

delfagio · 25-08-2015 11:30am

BarneyMc wrote:

Sounds fantastic and more floor depth to play with! Can I be cheeky and ask for a photo or 3?

I'd like to see photo too if possible, sounds like a good practical idea and solution for inside door matt.

Calahonda52 · 25-08-2015 11:33am

delfagio wrote: »

I'd like to see photo too if possible, sounds like a good practical idea and solution for inside door matt.

I will get one for ye later

delfagio · 25-08-2015 2:54pm

Many thank calahonda

ht9zni1gs28crp · 26-08-2015 9:16am

Calahonda52 wrote: »

I will get one for ye later

Who are you and why are you in my house

:D:D:D

ht9zni1gs28crp · 26-08-2015 10:17am

Some Pictures attached

tbukela · 26-08-2015 1:43pm

miller_63 wrote: »

Some Pictures attached

Clever idea and very nice finish.
Food for thought.

BarneyMc · 26-08-2015 1:59pm

miller_63 wrote: »

Some Pictures attached

Excellent! Thanks very much for posting. I'll be doing this in my house so I will. :-)

delfagio · 26-08-2015 2:48pm

Thanks for the picture, likewise I think I will be considering doing this on front door and utility door. Clever idea. And looks good too

ht9zni1gs28crp · 26-08-2015 6:51pm

It works well, the Dog is currently being trained to wait on the matt too if it comes in with wet feet. I think getting him to actually wipe it may be a step too far though

Simple to lift out and beat it (the matt not the Dog). The carpet guy said to beat the hell out of them. Should last ages too.

BarneyMc · 26-08-2015 7:09pm

miller_63 wrote: »

It works well, the Dog is currently being trained to wait on the matt too if it comes in with wet feet. I think getting him to actually wipe it may be a step too far though

Dog-mat-ic!

BarneyMc · 28-08-2015 11:04am

delfagio wrote: »

It should be called "Stress Build" and not "Self Build".

Just looking at your floor make up again there, if you go with 50mm liquid screed option with a 15mm floor covering and 15mm clearance under doors this actually leaves you with 170mm left for floor insulation not 160mm. Little extra insulation in floors you could do.

I was always of the opinion that a 'heavier', 'slow release' floor was the way to go but maybe not. Maybe the extra 25mm gain by using the liquid screed would be best?

PROJECT K · 28-08-2015 11:15am

BarneyMc wrote: »

I was always of the opinion that a 'heavier', 'slow release' floor was the way to go but maybe not. Maybe the extra 25mm gain by using the liquid screed would be best?

all depends on heating system, occupancy profile, building/glazing orientation, floor covering, thermal mass of other building elements etc etc - there is no 'best' way. I have opted for 75mm sand/cement screed downstairs (with 10mm porcelain tiles) as I have a lot of south facing glazing, large open plan areas and a low output (a/w heat pump) heating system. I want the downstairs to slowly regulate temperature as my wife is home 4-5 days per week and im there at least three days per week (inc. w/ends). Upstairs I have opted for 50mm liquid screed as the bedrooms are a little more shielded from direct solar gain and I want to be able to have better control over night time temperatures. Also, proposing timber floors upstairs, the benefit of a thermally massive floor is somewhat lost - the timber will act as a marginal insulator...

BarneyMc · 28-08-2015 11:31am

PROJECT K wrote: »

all depends on heating system, occupancy profile, building/glazing orientation, floor covering, thermal mass of other building elements etc etc - there is no 'best' way. I have opted for 75mm sand/cement screed downstairs (with 10mm porcelain tiles) as I have a lot of south facing glazing, large open plan areas and a low output (a/w heat pump) heating system. I want the downstairs to slowly regulate temperature as my wife is home 4-5 days per week and im there at least three days per week (inc. w/ends). Upstairs I have opted for 50mm liquid screed as the bedrooms are a little more shielded from direct solar gain and I want to be able to have better control over night time temperatures. Also, proposing timber floors upstairs, the benefit of a thermally massive floor is somewhat lost - the timber will act as a marginal insulator...

OK, this matches very closely to my situation also and was always my gut feeling. We are also at home a lot, lots of south facing windows, a/w heat pump, no slabs on the walls. The liquid screed upstairs sounds right also for the reasons you've outlined plus I don't think I have the floor depth there anyway!

Just got this back by the way for U Values showing diminishing returns kicking in:
150mm PIR = 0.12
160mm PIR = 0.11
170mm PIR = 0.11

This is probably my optimal ground floor makeup then (250mm to play with):

Sand/cement Option
External door gap 10mm
Tile/laminated floor 15mm
Sand/cement 75mm
Floor insulation (PIR) 150mm

The 10mm gap should be ok then for door clearance and future thicker floors then?

rampantbunny · 28-08-2015 3:33pm

BarneyMc wrote: »

...The 10mm gap should be ok then for door clearance and future thicker floors then?

I'm having a chuckle here Barney.
We haven't even finished our houses and some of us are contemplating that it might be possible that in some distant future, we might want to put in thicker floors. That's the stuff of nightmares.

BarneyMc · 28-08-2015 9:13pm

rampantbunny wrote: »

I'm having a chuckle here Barney.
We haven't even finished our houses and some of us are contemplating that it might be possible that in some distant future, we might want to put in thicker floors. That's the stuff of nightmares.

Yeah, some of us think we're going to live to 500!!

Seriously though, ignoring future floor thickness levels, roughly what's the best level to finish off with - 5-10mm below the level of the door?

rampantbunny · 28-08-2015 10:27pm

BarneyMc wrote: »

Yeah, some of us think we're going to live to 500!!

Seriously though, ignoring future floor thickness levels, roughly what's the best level to finish off with - 5-10mm below the level of the door?

I don't know that there is a 'best' level Barney.
Have you physically looked at the difference between 5 and 10mm with respect to the threshold and an aesthetics point of view? In my opinion it is hardly discernible.

I wanted my thresholds as low as possible, but there are rebates in the alu strips at the thresholds of my front and back doors. I've been told that this allows you to run the tile/wooden floor underneath to hide the joint. Not sure what distance this rebate is from the top of the threshold but it will dictate my threshold height if I use as described.

PM sent re. the installers on my job. I believe we had the same fellas.

Technophobe · 29-08-2015 6:52pm

Another example of recessed mat idea...Works very well for us..

BarneyMc · 16-01-2016 12:58am

PROJECT K wrote: »

all depends on heating system, occupancy profile, building/glazing orientation, floor covering, thermal mass of other building elements etc etc - there is no 'best' way. I have opted for 75mm sand/cement screed downstairs (with 10mm porcelain tiles) as I have a lot of south facing glazing, large open plan areas and a low output (a/w heat pump) heating system. I want the downstairs to slowly regulate temperature as my wife is home 4-5 days per week and im there at least three days per week (inc. w/ends). Upstairs I have opted for 50mm liquid screed as the bedrooms are a little more shielded from direct solar gain and I want to be able to have better control over night time temperatures. Also, proposing timber floors upstairs, the benefit of a thermally massive floor is somewhat lost - the timber will act as a marginal insulator...

Had to dig up this old post and can't believe it was last summer when it was written! Amazing how slowly things happen. My plasterers will be finished on Monday and the next big hurdle is the floor.

I've brought up Project K's opinion on the floor. My situation is very similar but I hope to make good use of a wood burning stove and not rely so much on the UFH. This might mean I'll want better control and quicker response time and might mean I'll go with a liquid screed floor. Probably not the biggest decision I'll ever make but I'd love to hear some opinions on this.

Ground Floor Makeup

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