DIY Sand and Cement screed?

[BTC Builder]

I was wondering if anyone had done their own sand and cement (75mm) floor screed and what the correct mix would be? 

 

I was thinking 3:1 with concreting sand and sbr but don't really know if this would be suitable with the underfloor heating?

[Onoff]

I considered sand and cement screed but in the end I did 100 mm wet concrete with A142 mesh in. Wetted with Everbuild Waterproofing additive. I levelled it using screed rails. 

[Nickfromwales]

1 hour ago, BTC Builder said:

I was wondering if anyone had done their own sand and cement (75mm) floor screed and what the correct mix would be? 

 

I was thinking 3:1 with concreting sand and sbr but don't really know if this would be suitable with the underfloor heating?

How big an area?

[Onoff]

Some interesting mix info here ref using SBR:

 

"P.R. EPOXY - SBR POLYMER SYSTEM

TECHNICAL DATA SHEET

USES.
P.R. Epoxy - SBR Polymer System is used for screeds, floor repairs, waterproof renders, waterproof fine concretes and bonding.

DESCRIPTION
P.R. Epoxy - SBR Polymer System has been formulated to enhance the physical and chemical properties of cement mortars and concretes. It is compatible with most forms of cement, sands and aggregates. Together with the cement, it forms a powerful adhesive to bond the aggregates together, producing a tougher, waterproof and more impact and abrasion resistant floor, repair mix, render or bonding primer.

PROPERTIES
The properties of the cured mix will vary depending on the type of cement, sand and aggregates used.

COMPRESSION
AGE. N/mm²
1 day 14 – 18
28 days 40 – 50
(Strength is dependent on mix design)

PREPARATION
Surfaces to which P.R. Epoxy - SBR Polymer System mixes are to be applied must be clean, strong and free from oil, grease and with a rough profile. Best preparation is with a scabbler or power washer. If metal surfaces area to be covered they must be rust free and wire brushed or grit blasted. Cement based substrates must be damped with clean water and excess water removed. A primer coat of 1:1 P.R. Epoxy - SBR Polymer System/cement is brush applied to the prepared surface. Refer to relevant standards and codes of practice.

MIXING & APPLICATION
Hand mix or use a forced action mixer. The components of the selected mix are measured by weight or volume and dry mixed. The P.R. Epoxy - SBR Polymer System and water is added to give the desired consistency. In an efficient mechanical mixer, mixing should continue for 2-3 minutes. When hand mixing, mix the cement, aggregate and sand dry then add sufficient of the P.R. Epoxy - SBR Polymer System/water until a homogeneous consistency is achieved.
The mixed mortar is applied to the prepared and primed surface whilst the primer is still wet/tacky, using conventional screeding, rendering and concreting techniques. Apply as required on to wet or tacky primer, compact well and finish. If the primer dries, crosshatch scratch and reapply. If necessary apply mortar in multiple layers to achieve total thickness, priming between layers with P.R. Epoxy - SBR Polymer System :cement primer.

STORAGE
P.R. Epoxy - SBR Polymer System must be stored unopened in dry warehouse conditions between +5°C and 25°C and out of direct heat and sunlight. In these conditions P.R. Epoxy - SBR Polymer System should have a shelf life of approximately 12 months.

PACKAGING
P.R. Epoxy - SBR Polymer System is available in 5, 25 and 240.0litre containers.

HEALTH & SAFETY
There are no emissions of noxious or offensive fumes, P.R. Epoxy - SBR Polymer System is alkaline when mixed with cement and sand; do not allow prolonged contact with skin. Health & Safety information is available.

OTHER INFORMATION
Mix Design’s

1. Floor Screeding and Screed Repair (min. 6mm)
by weight by volume
50kg cement 1 pbv
150kg medium sand 2.5 pbv
10 litres SBR (1:1 SBR:water
9 litres water* (add to consistency
Yield approx 0.1m³

2. Heavy duty floor toppings (min. 12mm)
by weight by volume
50kg cement 1 pbv
75kg medium sand 1.25 pbv
75kg 6-3mm grano chips 1.25 pbv
10 litres SBR (1:1 SBR:water
9 litres water* (add to consistency
Yield approx 0.11m³

3. Waterproof Renders (min.6mm)
by weight by volume
50kg cement 1 pbv
125kg medium sand 2 pbv
10 litres SBR (1:1 SBR:water
9 litres water* (add to consistency
Yield approx 0.1m³

4. Water Resistant Concrete (min.25mm)
by weight by volume
50kg cement 1 pbv cement
100kg medium sand 1.5 pbv
100kg 10-5mm pea shingle 1.5 pbv
5 litres SBR (1:3 SBR:water
13 litres water* (add to consistency
Yield approx 0.14m³

5. Bonding Screeds, Plaster, New Concrete to Old
by weight by volume
1kg cement 1 pbv cement
1 litre SBR 1 pbv SBR
Yield approx 3-4m² per litre

6. Floating Screeds (min. 38mm)
by weight by volume
50kg cement 1 pbv
150kg medium sand 2.5 pbv
4.5litres SBR (1:3 SBR:water
13.5 litres water* (add to consistency
Yield approx 0.1m³

• * = add to working consistency.
• All sands must be medium grade sharp.
• Aggregates must be clean, well graded and not “to dust”.
All P.R. Epoxy Systems products’ are manufactured to a high standard of quality. Whilst we aim to ensure that any advice, information or recommendations given are reliable and correct, the Company cannot accept any liability directly or indirectly arising from the use of its products, as we have no direct or continuous control over where or how its products are applied. No undertaking can be given against infringement of any patented processes."

[nod]

Unless it’s a small area It’s not worth it 

It needs to be semi dry Which is really hard to mix in a mixer 

[BTC Builder]

28 minutes ago, nod said:

Unless it’s a small area It’s not worth it 

It needs to be semi dry Which is really hard to mix in a mixer 

 

This is what i was wondering, I've seen it done on other jobs I've sub contracted to and would not attempt it semi dry. So wet mix is no good?

[torre]

I've done this for a small, say 8m2 extension with a friend helping mix and barrow, it's hard to mix well in a standard mixer and you need to keep the stuff coming. Your mix will probably be a bit inconsistent.

 

I'd suggest adding fibres to give the screed extra strength rather than SBR here.

 

I'd probably avoid doing it again and definitely avoid any larger area.

[BTC Builder]

I've got the man power and a large mixer so not worried in that regard, I just don't want to do the wrong mix that will crack or won't work with the underfloor heating 

[nod]

40 minutes ago, BTC Builder said:

 

This is what i was wondering, I've seen it done on other jobs I've sub contracted to and would not attempt it semi dry. So wet mix is no good?

Back in the day I would do full houses out like this The trick is to have the sand already damp Let the sand turn Then add dry cement No  water 

 

Ready mix is so cheap now and easy to collect small amounts It’s probably not worth the hassle 

 

[BTC Builder]

30 minutes ago, nod said:

Back in the day I would do full houses out like this The trick is to have the sand already damp Let the sand turn Then add dry cement No  water 

 

Ready mix is so cheap now and easy to collect small amounts It’s probably not worth the hassle 

 

From another thread, I know you're local to me. Can you recommend any suppliers of screed mix?

 

It's a large area, 140sqm and we wouldn't want it all in a day as we wouldn't be able to level it in one go. we'd split it into two and have an expansion joint in the middle (doorway) regardless of whether we do it all ourselves or have someone else supply the mix.

[JohnMo]

10 minutes ago, BTC Builder said:

140sqm

That is some volume to barrow in and mix

 

10.5m³. A barrow holds circa 85L. So about 125 barrow loads. Get a man with a lorry and pump, be sensible, you get a better job done without killing your self.

[Russell griffiths]

15 minutes ago, BTC Builder said:

From another thread, I know you're local to me. Can you recommend any suppliers of screed mix?

 

It's a large area, 140sqm and we wouldn't want it all in a day as we wouldn't be able to level it in one go. we'd split it into two and have an expansion joint in the middle (doorway) regardless of whether we do it all ourselves or have someone else supply the mix.

For this area get a screed company in, they will be in and out in a day and it will be spot on, I did traditional screed with fibres. 
fantastic finish from a company that does it all day everyday. 

[Onoff]

I'm not sure but think there's something about an SBR mix drying quicker than a mix without?

 

Edit: As in it's not useable for as long 

Edited Sunday at 08:29 by Onoff

[scottishjohn]

I would think its very hard to do a dry mix and get it perfectly level --thats why proper screed is very sloppy --so it self levels to an extent

 

 I would consider how you going to get it smooth and flat enough for your floor 

 

I know my floor men --would not even consider using stick down lvt without using self levelling  on top of the screed and then grinding it  before laying the floors

If your going to use cermaic tiles =--then not so much of a problem  but your screed still needs to be as perfect as possible

 

[Nickfromwales]

46 minutes ago, scottishjohn said:

 

I would think its very hard to do a dry mix and get it perfectly level --thats why proper screed is very sloppy --so it self levels to an extent

 

You need to see my guy in action then! He’s been screeding my jobs for over 25 years and it’s a dry S&C screed, with or without fibres, delivered to site the same day, and laid to within a couple of mm from one end of a building to the other. 
 

Paint it green and play snooker on it 2-3 days later.

 

@BTC Builder, he’s from my neck of the woods but works nationwide. If you want his details for supply and lay, PM me. He can price it over the phone. 

[Kelvin]

The pumped lorry for 164m2 was the quickest £4000 I spent on our house build. My other half wanted to see it go in for some reason but by the time she got here from the rental they were more or less finished. We were walking on it the following day and started work again the day after. The time and effort saved is worth the cost. Great level surface finish and no cracks but we did have plenty crack inducers. 

[FuerteStu]

I did the garage conversion floor in dry sand and cement mix.. Mixed on the driveway by a volumetric mixer. 

 

I calculated I needed 1.8m2, asked for 2 to be safe. 

 

Used a laser level and wheelbarrow.. Got it done in about 3 hours. 

 

However, the guy must have just emptied his wagon... It was the day before Xmas eve. I had over 2m2 left over on the driveway. Filled up two tonnebags with it and built a ramp to the front door as well.. 

 

Had to get a skip in the new year to get rid of it all.. That was the worst part of it all. 

 

If you want tips on doing it yourself I worked out a few. 

[nod]

3 hours ago, BTC Builder said:

From another thread, I know you're local to me. Can you recommend any suppliers of screed mix?

 

It's a large area, 140sqm and we wouldn't want it all in a day as we wouldn't be able to level it in one go. we'd split it into two and have an expansion joint in the middle (doorway) regardless of whether we do it all ourselves or have someone else supply the mix.

I used Ribble Valley 

Id 220 m2 and laid it over two days