hemihydrate and anhydrite floor screed?

ssloan · 24-10-2014 8:23pm #1

Have decided to to go with liquid screed for the the floor but trying to find which is best, hemihydrate and anhydrite floor screed?

What are the pros and cons?

Thanks

stuckintipp · 26-01-2015 12:10am

ssloan wrote: »

Have decided to to go with liquid screed for the the floor but trying to find which is best, hemihydrate and anhydrite floor screed?

What are the pros and cons?

Thanks

Bump.

I've to make a similar decision soon. What did you do and why?

Curious Geroge · 26-01-2015 11:43pm

stuckintipp wrote: »

Bump.

I've to make a similar decision soon. What did you do and why?

how many mm from door threshold to insulation? that will define how thick your screed will be and from that your options

stuckintipp · 27-01-2015 10:13am

55mm depth to insulation

BarneyMc · 02-02-2015 9:22am

ssloan wrote: »

Have decided to to go with liquid screed for the the floor but trying to find which is best, hemihydrate and anhydrite floor screed?

What are the pros and cons?

Thanks

Speaking to a friend at the weekend and he seems to think a concrete first floor would be best option. I was under the impression a liquid screed one would be better for control of temp. Any thoughts on this?

paidioc · 30-03-2015 5:43pm

stuckintipp wrote:

I've to make a similar decision soon. What did you do and why?

Hi stuckintipp. Did you decide on your screed yet? I've just started our house and am torn over the finished floor. I was originally thinking of going with concrete floor and doing it now but am getting second thoughts and looking into screeds now

stuckintipp · 23-04-2015 8:55am

ya we went with the gypsum based floor screed. To be honest were very disapointed by both the product, contractor and supplier.

We were promised extremely fast setting and hardening times, this did not happen. After 2 weeks it was stillsoft, if a block was dropped on it a dent was forming on the surface. after much hassle they then came back and put a 2nd hard top layer on the original surface.

Now 3 months later things on the surface seem fine but we are unsure about the original screed. The underfloor heating hasnt been turned on yet , weve been promised that when its on the materials will bond and itll harden up.

To sum up, its been a poor experience not helped by the customer service of the contractor and screed supplier. it was sold as a superior product with the price to match and this has been the case.

rampantbunny · 24-04-2015 2:22pm

stuckintipp wrote: »

To sum up, its been a poor experience not helped by the customer service of the contractor and screed supplier. it was sold as a superior product with the price to match and this has been the case.

Haven't heard of a gypsum product...can you PM the exact product name stuckintipp.

..and you might have a bit of a typo above... 'and this hasn't been the case I presume you meant.

BarneyMc · 24-04-2015 4:01pm

Would sand/cement be a better option if space permits?

hexosan · 24-04-2015 4:44pm

When the liquid screed is done right it's a great job. Makes filing and flooring a lot easier. There's a lot less work in the liquid screed putting it in after the house has windows and internal plaster.
It's a pig of a job to wheelbarrow cement in.

rampantbunny · 24-04-2015 4:47pm

hexosan wrote: »

When the liquid screed is done right it's a great job. Makes filing and flooring a lot easier. There's a lot less work in the liquid screed putting it in after the house has windows and internal plaster.
It's a pig of a job to wheelbarrow cement in.

Can you pump the cement screed in or is it too dry? I haven't seen it done.

hexosan · 24-04-2015 5:30pm

You can pump it but then your adding the cost of the pump to the price. While the liquid is more expensive at first glance when you add everything up (concrete, pump, labour) there's not a massive gap in the price.

Sligoronan · 26-04-2015 8:29am

I have used a hemihydrate calcium sulphate based screed on lots of jobs. Got another job poured on Friday and would never go back to sand and cement again. Product cost €240 a cubic meter and €5 a square meter to install.

BarneyMc · 26-04-2015 9:26am

Sligoronan wrote: »

I have used a hemihydrate calcium sulphate based screed on lots of jobs. Got another job poured on Friday and would never go back to sand and cement again. Product cost €240 a cubic meter and €5 a square meter to install.

Why never again to sand/cement?

hexosan · 26-04-2015 9:58am

Sligoronan wrote: »

I have used a hemihydrate calcium sulphate based screed on lots of jobs. Got another job poured on Friday and would never go back to sand and cement again. Product cost €240 a cubic meter and €5 a square meter to install.

Back of a fag box calculation

100m2 floor of sand & cement @ 75mm = 7.5 m3

(1) cube of concrete 35N10 approx €80 (approx)

7.5m3 x €80 = €600
+ approx €700-€1000 in labour to lay the screed
Total - €1300-€1600

* (not counting conveyor belts [€70] or the need for a concrete pump [€500-€800]

100m2 floor of liquid screed @ 50mm = 5m3

5m3 x €240 = €1200
+ €5/m2 labour = €500
Total - €1700

So liquid screed is between €100 & €400 more expensive than sand & cement for a 100m2 floor. It's cheaper if you need to use a concrete pump. Plus with sand & cement you can only pour one floor at a time and the first floor needs to be propped with acrows beneath while the screed sets. Multiple floors can be poured in the one day with liquid screed and they don't need to be propped. I can be corrected here but I think they claim they can pour 1000m2 per day.

Based on the figures above given by sligoronan.

Sligoronan · 26-04-2015 10:12am

BarneyMc wrote: »

Why never again to sand/cement?

1. It can go in at 45mm plus so when I use it on the first floor it dose not weigh as much and it the allowed me use joisting instead of hollow core.

2. When using on ground floor it allowed me to use 125 insulation 50mm of screed plus what ever floor finish and keeps the step outside the doors to about 150mm.

3. No cracking or ravelling so better when using glue down floors.

4. To quote the info on the label it is a solid high-density screed with a greater thermal conductivity than traditional screeds. As a result of this, under floor heating systems can operate at significantly lower temperatures than those used with traditional screed, to produce the equivalent room temperatures. The liquid nature of the screed enables it to fully encapsulate the under floor heating pipes, to give maximum heat transfer into the screed. Ultraflo greatly improves the efficiency of under floor heating systems and significantly improves the heat response time.

Sligoronan · 26-04-2015 11:28am

hexosan wrote: »

Back of a fag box calculation

100m2 floor of sand & cement @ 75mm = 7.5 m3

(1) cube of concrete 35N10 approx €80 (approx)

7.5m3 x €80 = €600
+ approx €700-€1000 in labour to lay the screed
Total - €1300-€1600

* (not counting conveyor belts [€70] or the need for a concrete pump [€500-€800]

100m2 floor of liquid screed @ 50mm = 5m3

5m3 x €240 = €1200
+ €5/m2 labour = €500
Total - €1700

So liquid screed is between €100 & €400 more expensive than sand & cement for a 100m2 floor. It's cheaper if you need to use a concrete pump. Plus with sand & cement you can only pour one floor at a time and the first floor needs to be propped with acrows beneath while the screed sets. Multiple floors can be poured in the one day with liquid screed and they don't need to be propped. I can be corrected here but I think they claim they can pour 1000m2 per day.

Based on the figures above given by sligoronan.

Would agree with above. Some added points. Basing on load calculations for last few houses the cement screed upstairs at 75mm would be a non runner. Of coarse if constructing a bungalow the cement screed would be the way to go if you can get over the threshold details for part m.
If using hollow core the cement would be the way to go.
But personable I don't like hollow core as ya then have to drop ceilings to allow for sewerage piping and heat recovery. I find it much easier on all trades to use joist trusses layer of ply and 45-50mm of screed.

BarneyMc · 26-04-2015 12:49pm

What are load calculations - the weight that can be taken on the 1st floor?

Sligoronan · 26-04-2015 1:42pm

BarneyMc wrote: »

What are load calculations - the weight that can be taken on the 1st floor?

All depends on spans and what timber type.
Your engineer will be able to do calculation and advise.

ronn · 10-05-2015 6:52pm

Anyone pm me some screed companies that they'd recommend in the Wicklow/Dublin, I've tried 3 different companies one wasn't interested and another is calling out to measure up, the 3rd has got back to me as yet,

frankledwith · 27-03-2016 1:37am

hexosan wrote: »

Back of a fag box calculation

100m2 floor of sand & cement @ 75mm = 7.5 m3

(1) cube of concrete 35N10 approx €80 (approx)

7.5m3 x €80 = €600
+ approx €700-€1000 in labour to lay the screed
Total - €1300-€1600

* (not counting conveyor belts [€70] or the need for a concrete pump [€500-€800]

100m2 floor of liquid screed @ 50mm = 5m3

5m3 x €240 = €1200
+ €5/m2 labour = €500
Total - €1700

So liquid screed is between €100 & €400 more expensive than sand & cement for a 100m2 floor. It's cheaper if you need to use a concrete pump. Plus with sand & cement you can only pour one floor at a time and the first floor needs to be propped with acrows beneath while the screed sets. Multiple floors can be poured in the one day with liquid screed and they don't need to be propped. I can be corrected here but I think they claim they can pour 1000m2 per day.

Based on the figures above given by sligoronan.

I'm trying to decide which screed to use also. I'm at backfill stage. My figures are, 7.5 cubic metres of 30N10 =525 euro + 240 labour for two lads to install=765. Liquid screed installed is 1700 for same area. So I'm faced with a difference of 935euro. The concrete screed will utilise night rate electricity better. The extra 935 would take 15years to recoup

e.r · 29-03-2016 7:02pm

frankledwith wrote: »

I'm trying to decide which screed to use also. I'm at backfill stage. My figures are, 7.5 cubic metres of 30N10 =525 euro + 240 labour for two lads to install=765. Liquid screed installed is 1700 for same area. So I'm faced with a difference of 935euro. The concrete screed will utilise night rate electricity better. The extra 935 would take 15years to recoup

Bear in mind if your tiling easy screed have to dry to 0.5% moisture content. Where as concrete only needs to shrink 28 days

BarneyMc · 29-03-2016 8:03pm

e.r wrote: »

Bear in mind if your tiling easy screed have to dry to 0.5% moisture content. Where as concrete only needs to shrink 28 days

Irrespective of depth?

e.r · 29-03-2016 8:52pm

BarneyMc wrote: »

Irrespective of depth?

Yes for both cases, concrete normally allow 4-6 weeks rule of thumb, for the shrinkage, moisture will not affect tile adhesive.
Easy screed the depth will dictate the time it takes drying UFH system will help this, but you need to prime before hand as dry gypsum and wet cement don't mix.

frankledwith · 29-03-2016 11:48pm

I've made my decision on what floor system to use. I'd like feeback from anyone with a valid opinion. I've backfilled with two feet of broken stone with 200mm of small pebble/sandy gravel on top. Well vibrated . Radon barrier is next with 120 ballytherm on top. A192 mesh with the UFH pipes cable tied on top at 150mm centres. 100 mm of 30N10 concrete to finish. Should have a slow response time availing of the night rate. Hoping to get the concrete level with a nice flat finish. Anyone do anything similar?

BryanF · 30-03-2016 8:22am

frankledwith wrote: »

I've made my decision on what floor system to use. I'd like feeback from anyone with a valid opinion. I've backfilled with two feet of broken stone with 200mm of small pebble/sandy gravel on top. Well vibrated . Radon barrier is next with 120 ballytherm on top. A192 mesh with the UFH pipes cable tied on top at 150mm centres. 100 mm of 30N10 concrete to finish. Should have a slow response time availing of the night rate. Hoping to get the concrete level with a nice flat finish. Anyone do anything similar?

More insulation required. Has your arch approved this spec with ufh?

hexosan · 30-03-2016 8:40am

I'd be sticking 200mm of the ballytherm in its not like you can add more in after.

frankledwith · 30-03-2016 8:46am

BryanF wrote: »

More insulation required. Has your arch approved this spec with ufh?

Thanks Bryan, what's an Arch? Just joking, I'm a self builder and I'm also the designer. There's a lot of opinions on insulation , from 75 to 200. My engineer recommended the 120mm though. The mesh, pipe and slab are my design. I carried out a lot of research on this. I think the ,way we live, this should work fine. Have you a recommendation? What about the slab as a radiator? I've nothing poured yet.

chillit · 30-03-2016 9:04am

I'm a self builder too and my research to date seem to indicate that 120mm floor insulation is just about compliant with the general part L requirements and I think that is if you are using standard rads. Much better to go for at least 150mm I think. If you want to future proof even more then go 200mm but you have to balance the cost benefit I think.

BryanF · 30-03-2016 11:33am

frankledwith wrote: »

Thanks Bryan, what's an Arch? Just joking, I'm a self builder and I'm also the designer. There's a lot of opinions on insulation , from 75 to 200. My engineer recommended the 120mm though. The mesh, pipe and slab are my design. I carried out a lot of research on this. I think the ,way we live, this should work fine. Have you a recommendation? What about the slab as a radiator? I've nothing poured yet.

Let me put this another way.

1. As a self builder have you conplied with part L?

2. Have you carried out a provisonal BER

3. And what is the 120mm Insulation u-value.

4. Are you aware that ufh requires a Min of .15wm2k floor uvalue

frankledwith · 30-03-2016 12:02pm

BryanF wrote: »

Let me put this another way.

1. As a self builder have you conplied with part L?

2. Have you carried out a provisonal BER

3. And what is the 120mm Insulation

4. Are you aware that ufh requires a Min of .15wm2k floor uvalue

I've gotten a ber and deap report showing .15For the floor or better, I'll have to check

hemihydrate and anhydrite floor screed?

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