Traditional Sand/Cement Screed

These screeds are generally laid between 50mm and 100mm thick. These screed can be used in all situations where a final covering is applied. Sand cement screed can be laid to falls and is suitable for wet areas but will not tolerate being saturated. Shower areas etc need to have a waterproof covering i.e. vinyl, tiles etc.

There are various types of this screed which are:-

• 1.4 cement/sand used in all general situations
• 1.3 cement/sand used where a stronger screed is required

The above screeds can be used with additives for certain situations:-

• Fibre reinforcing used to reduce cracking.
• S.B.R. used where a thinner screed is required. This additive is suitable for wet areas.
• E.S. screed used to achieve a faster drying time.

These types of screeds are generally laid at a rate of 100m2 per day per three man gang.

The main failure of this type of screed is caused by poor compactation.

Sand/cement screeds can be subject to shrinkage cracking and curling.

Drying time is approximately 1mm per day depending on temperature and air humidity.

As well as traditional screeds there are specialist screeds that can be covered within 24 hours after laying. These screeds are site batched using specialist plant.

All sand/cement screeds can be pumped into position.

Flowing calcium sulphate screeds

These screeds are gypsum based and are pumped into position. The advantages of this screed over sand/cement screed are:-

• This screed is laid thinner than traditional screed i.e. 40mm calcium sulphate screed is equal to 75mm sand/cement screed.
• Drying time is the same as sand/cement screed but is reduced due to laying thinner.
• Full compaction is always achieved because the product is liquid.
• Shrinkage cracking and curling is unlikely to occur.
• Areas of 1000m2 per day can be covered by a single gang of four men.
• These screeds are especially suited to under floor heating because they fully encapsulate the pipes which in turn conduct the heat more efficiently.

The disadvantages are:-

• Cannot be laid to falls.
• Care has to be taken with the final coverings i.e. adhesives need to be compatible with the product. A sealer is necessary if cement based products are used.

Flowing screeds cement based

These screeds have all the advantages of calcium sulphate screeds and are compatible with all cement based adhesives but cannot be laid to falls.

All base screeds achieve a finish suitable for tiles and carpets but may need further treatment for thin vinyls.

Thin coat screeds

In general these screeds are laid between 3mm and 10mm thick and can be used in all situations where a flat smooth finish is required. Screed types vary from domestic to heavy industrial. Situations where these screeds can be used:-

• Industrial for refurbing concrete floors heavy duty screeds are able to take fork lift traffic.
• Poorly laid and out of level concrete floors can be brought back to a first class finish.
• Refurb and renovation work even over old timber floors.

All these screeds will give a finish capable of taking over all final coverings.

Heavy duty screeds do not need any final covering and can be compared to ordinary concrete.