Sand/cement or liquid screed for floor

ssloan

Going with UFH in house and trying to decide between sand/cement for floor or liquid screed for the floors? Does anyone have opinions and approx. extra cost of the liquid screed? Is the advantage if liquid screed only in the initial heat up with with UFH?

glashanator

ssloan wrote: »

Going with UFH in house and trying to decide between sand/cement for floor or liquid screed for the floors? Does anyone have opinions and approx. extra cost of the liquid screed? Is the advantage if liquid screed only in the initial heat up with with UFH?

Depends what you're looking for. If you both are out all day and home late, then you might want a faster shorter heat up time, liquid screed might suit.

If home all day ,definitely sand and cement.

Best way to think of underfloor heating is like a storage heater, heats up and releases heat all day. thats why the vast majority go with sand cement screed.

Any new builds well insulated and airtight houses now adays are moving away from the heat up fast cool down fast method of heating. Its all about getting heat into the house slowly , then keeping there, topping it up slightly as the temp drops slightly, more efficient and comfortable way to run your home. And again, this is why sand and cement screed is used.

Liquid screed can be up to 50% more expensive in areas, probably more.

declan52

For mine the cost difference was 650 for 140sqm of floor. I went for sand cement as you can have issues with getting tiles to bond to the top of the liquid screed if its not sanded down and sealed correctly.

BarneyMc

I am looking at these 2 options also. I will have UFH in a 2800 sq feet house and using a air to water HP as the main source of heat. I'll also be lighting a solid fuel stove and I work from home.

This would tend to lean towards the sand/cement option and use the cheaper night rate electricty. However, I would like to install PV cells in the future and this would work better, I think, with a more responsive heating system, i.e. liquid screed.

It's a hard one to call!!!!

RITwing

Opinion only.

The desirbility of seeking fast reponse from UFH comes from our culture of badly built houses. We are used to coming in from the cold to a badly insulated and drafty house and like to boiler to work like buggery to give us hot rads and a warm house in minutes.

But building to current regulations will require high levels of insulation , air tightness and a properly designed and installed ventilation system.
So the manner in which the houses is heated is by a slow constant trickle.

Thin screeds and fast response do not offer any advantage then.

BarneyMc

If I'm lighting a stove every day then maybe I'd want the heating system (heat pump) to adjust accordingly and not 8 hours later?

RITwing

If you build to b reg standards you should find that you are in fact not needing to light the stove every day. Once the house is warmed up initilally over 3-4 weeks then the HP will be fine save for the most bitter winter days.

BarneyMc

Pumping 250mm cavity, HRV, high levels of insulation, etc. My walls will be a good heat 'sink'.

I hope to heat the stove as needed and as I work from home it will not be a bother to light and keep going. For the days that I don't bother to light it or on very cold snaps would it not be better to have the HP respond quickly as needed?

Also if going the PV cell route sometime in the future, if there's an 8 hour delay for the heat to be released from a sand/cement floor then it will only be released late and not during the day when I need it (I work from home)?

DeeJunFan

BarneyMc wrote: »

Pumping 250mm cavity, HRV, high levels of insulation, etc. My walls will be a good heat 'sink'.

I hope to heat the stove as needed and as I work from home it will not be a bother to light and keep going. For the days that I don't bother to light it or on very cold snaps would it not be better to have the HP respond quickly as needed?

Also if going the PV cell route sometime in the future, if there's an 8 hour delay for the heat to be released from a sand/cement floor then it will only be released late and not during the day when I need it (I work from home)?

Suppose it depends Barney.

If you are keeping your slab at a constant temp to keep the house comfortable with your levels of insulation and good air-tightness i doubt you will have a situation where you are going to be looking for immediate response from the slab. More likely you will be living in comfortable conditions 95% of the year with your UFH and only lighting the stove on really cold days.

Do you know how much heat you need in your house to get it up to temp?

I have been in a well insulated and fairly air-tight. (not as air tight as people aim now) and when the stove is lit its generally put out within a hour or two as it over heats the space.

BarneyMc

DeeJunFan wrote: »

Suppose it depends Barney.

If you are keeping your slab at a constant temp to keep the house comfortable with your levels of insulation and good air-tightness i doubt you will have a situation where you are going to be looking for immediate response from the slab. More likely you will be living in comfortable conditions 95% of the year with your UFH and only lighting the stove on really cold days.

Do you know how much heat you need in your house to get it up to temp?

I have been in a well insulated and fairly air-tight. (not as air tight as people aim now) and when the stove is lit its generally put out within a hour or two as it over heats the space.

Will dig out the heat requirement later and post.

The house where the stove over heats the house sounds like one where the walls are dry lined?

BarneyMc

The big advantage I see with going the sand/cement route is to 'charge' the slab at night rate electricity.

In a very well insulated house that is not dry lined and where a stove will be lit daily (as needed) then surely the demand on the HP would be minimal. Therefore would it not be better for the HP to come on for a short period during the day (warmer temps) when and if required and have the heat in 1-2 hours? There is a higher monthly rental for the night rate meter I believe so this could be saved also (just run the HP during the day).

Another factor is the possibility of using PV cells to power the HP. As this could only happen during daylight hours it would be good to have the heat appear in the house within 2 hours rather than 8 hours?

BarneyMc

Can anyone else out there share their experience/thoughts of which floor type to go for? Is it possible to have a 3 inch sand/cement floor?

declan52

BarneyMc wrote: »

Can anyone else out there share their experience/thoughts of which floor type to go for? Is it possible to have a 3 inch sand/cement floor?

I have just 70mm of sand cement on mine. It got mixed with fibres to strengthen it. It is down near 4 months and on the bits not covered by flooring there are no cracks. I also added mapie 704 to increase the drying out time. Floor was dry after 21 days.
Takes about 2 hrs to heat up with ufh and stays warm for 5-6 hrs. How long it stays warm will depend on how well insulated and airtight your house is.

BarneyMc

declan52 wrote: »

I have just 70mm of sand cement on mine. It got mixed with fibres to strengthen it. It is down near 4 months and on the bits not covered by flooring there are no cracks. I also added mapie 704 to increase the drying out time. Floor was dry after 21 days.
Takes about 2 hrs to heat up with ufh and stays warm for 5-6 hrs. How long it stays warm will depend on how well insulated and airtight your house is.

What are the fibres called?

declan52

Not sure what their technical name is the screed guys brought them. They look like a plastic rope that has been shredded. About 50mm long width of hair type thing. Whoever is doing your floor will know about them.

Hollywood130

I'm looking at floor screeds myself now, not putting in UFH, and not sure whether to go sand/cement or self-levelling floor screed. For supply only from a local company, sand/cement is €100 per meter and the self-levelling is €172. Tilers have said self-levelling is better as they won't have to use any bonder. But the company I rang for a quote said I should only need sand/cement because I'm not putting down underfloor heating... help please...

declan52

You are better of going for sand cement if you have no ufh. The flo screeds all need sanded and sealed and if you are tiling you def need this done or your tiles won't stick to the floor. No matter what screed you will pick you will have to use some sort of bonding solution to help the adhesive stick to the floor.

Hollywood130

Ok, is 80mm ok to go for in sand/cement? That takes the floor level with our front door. The plans say 50mm but that would barely cover the plumbers pipes and it won't bring the floor level with the doors. I was told we could go as high as we wanted, 80mm is definitely sufficient though

declan52

Have you any insulation on the floor.

Hollywood130

Yes the insullation went in with the sub-floor

declan52

OK. 80mm screed will do but you only have 30mm coverage over the pipes. Not much and you might get cracks at these points.

Hollywood130

declan52 wrote: »

OK. 80mm screed will do but you only have 30mm coverage over the pipes. Not much and you might get cracks at these points.

Would you recommend more screed?

declan52

Are you putting the screed down yourself. Sounds like it. The depth of the screed is determined by your door head heights. Can't put 80mm down if there will be 50mm of a gap under the door when its hung or you wouldn't want to be cutting 25mm of the bottom of a door if you put to much in.

Hollywood130

declan52 wrote: »

Are you putting the screed down yourself. Sounds like it. The depth of the screed is determined by your door head heights. Can't put 80mm down if there will be 50mm of a gap under the door when its hung or you wouldn't want to be cutting 25mm of the bottom of a door if you put to much in.

We bought the house at builders finished basically, the plans say 50mm but when you measure to the door theres 80mm room for screed, 50mm wouldn't bring the floor to the door heights, with 80mm its even with the door. No we'll have someone put it down, we wont be doing it ourselves. Just pricing around at the moment, not too many in my area doing

declan52

Measure from the inside of your internal door frames. You need min of 2m to allow for a standard door height and that will give you enough for a 10mm tile. If you are going for a solid floor then you need a bit more.

Hollywood130

declan52 wrote: »

Measure from the inside of your internal door frames. You need min of 2m to allow for a standard door height and that will give you enough for a 10mm tile. If you are going for a solid floor then you need a bit more.

Thats great, thank you so much for your help

delfagio

Hi Hollywood130,

Just seen this thread and said I would jump in really quick. You mention that you are going to put down 80mm sand/cement screed and that this would bring you level with the door (exterior front door I assume), just make sure you remember to take into account the depth of floor finishes so that your front door, side door, back door can still open. Floor tiles can be approx. 10mm thick and you may need possibly 3-5mm bed of adhesive, even solid wooden floor can be almost 18mm thick.

No point putting screeded floor in exactly level with front door only to find you only have 5-10mm clearance from the bottom of the door to the top of the screeded sand/cement floor because you would not have enough room to lay your floor finishes and still be able to open the door.

Maybe you have considered this, but just thought I would mention it, as I almost got caught with that myself.

Hollywood130

Initially I hadn't considered this but then looked at the sample tiles and thought 'Oh ya'!!! With 80mm there is still space for floors though. We have a guy calling tomorrow to have a look and give at price on laying the screed so we'll see what he has to say.

delfagio

Brilliant, good on ya , hope all goes well with the screed and finished floors, I'm just in the process of getting ready for laying my own insulation, underfloor heating pipes downstairs & upstairs and then hopefully pouring the screed before end of this month. :eek:

Hollywood130

You too, it's a stressful process, very hard to keep an eye on everything when you're working full time. Wow before the end of this month?? Our plasterer is starting 24th of this month so it will probably be mid-February before I get laying screed. Are you pouring screed before plastering?

delfagio

Hey Hollywood130,

No I have all the internal plastering finished. We went with a timber frame SIP panel construction, so all our internal walls just need to have plasterboard/insulated plasterboard fixed to them and then skim coated.

Be prepared though.....plastering is a messy trade. We were keeping the house clean on a weekly basis which was working fine......then the plasterers came to do their work and the place turned into a bomb site, dust from plaster boards, screws everywhere, off cuts of plasterboards everywhere, skim coat on floors, windows, just a mess, was glad to see the end of the plastering stage ha ha

Yea its tough keeping up with it all and working full time as well, lots of late nights, early mornings & late nights at weekends, we should be in all going well for mid March, paddy's week sometime

Hollywood130

That's what I'm afraid off, will have to keep an eye out there once the plastering starts. That reminds me... must cover the windows so the plaster doesn't destroy them... thanks! Going to do a clean up after the weekend, it's in a bit of a mess after the electrician & we needed to drill more holes for vents. Need to change some plasterboards aswell so I can only imagine the mess that will happen

Oh lucky you, I'm aiming for May all going well. Best of luck with it, hope it all goes well for you.

delfagio

Hollywood130,

I wouldn't worry too much about the windows, it is an awful hassle trying to cover them up, takes a good bit of time and taping, plus the plasterers will need to skim tight into the edges of the windows. It doesn't take long to give them a quick wipe over and the plaster does come off easy. Just tell your plasterers that you want them to wipe the windows down after they finish each room. If they are decent & good plasterers they will do this out of respect, and pride in their own work, but I would still mention it to them anyway.

However I did stick some black plastic bags over our window boards, as they are MDF, and didn't want them getting too wet. I just left the plastic shy about 40mm from the wall reveals so the plasterers could still skim right up to the window board, it meant they would be taking the plastic off that I just put on.

Best of luck to you with the build, roll on May for you,

rampantbunny

When you were covering your window boards delfagio, could you not have just run the covering to the block walls and let the plasterer plaster to it. What difference if it gets plastered over?

Couldn't you trim the cover off later at the plaster line with a blade?
(I'm presuming your covering was thin plastic).

Or does the plaster have to stick to the window board and windows for some reason?

BarneyMc

There's a blue film that you can get which self sticks to the windows. It's not cheap but works a treat for such jobs.

rampantbunny

BarneyMc wrote: »

There's a blue film that you can get which self sticks to the windows. It's not cheap but works a treat for such jobs.

Cheers Barney. Have another thread on this very thing. Got some of this film today...it should be removed after 10 days to ensure no residue is left behind which is a bit of a short life. €30 for a 100m roll (either in blue or clear) so could take off and reapply but what a pain.

Might be other products out there that you can leave longer but need to get cracking so the research is gone out the window.

Still though, I'm planning on just cutting the film where it meets the plaster unless I get a reason not to do this.

delfagio

Hi rampant bunny,

I just used black bin bags and some tape to stick them on, but the plastic you have would be spot on too. Well for me, I just didn't want to have to be cutting the plastic later on and running the rise of still seeing a very thin line of plastic at the bottom of the plastered reveal where it meets the window board. For this reason along I just stopped it short about 40mm and as said it meant the plaster could finish nice and tidy along the window board with a nice sharp line.

I suppose it is up to yourself what you would prefer. For me though I would leave it just short about 40mm, that way you won't be out trimming off the plastic later with a nice.

BarneyMc

Just going back to the original topic, for the first floor is the liquid screed option favoured as it is easier to control (thinking of bedrooms rather than ground floor living areas)?

oxo121

Hi all,

Just wondering would anyone know roughly the price per m2 of sand cement floor screed pumped labour only?? Would appreciate your help.

oxo