Joints & Bays
Central Flow Screeds are suitable for application to most types of sub bases demonstrating an excellent degree of dimensional stability (max shrinkage/expansion on drying of 0.02%) when compared to traditional sand cement based screeds.
Maximum Bay Length
Maximum Bay Sizes
The edge strip recommended for use with liquid/flow screeds is generally 8-10mm foamed polyethylene with an attached polythene skirt, this thickness relates directly to the maximum allowable positive movement within the screed.
It is recommended that very large pours of floating or unbonded construction with a dimension >30m but <40m without a break such as a dividing wall should include a bay joint of compressible material such as Flexcellor Ethafoam.
Alternatively, on hardening a saw cut to the full depth of the screed can be included to form the day joint.
As with all types of screed a joint must be formed above all structural movement joints.
On larger pours the following guidelines may be of use when considering the layout of any day-work or bay joints during screed placement.
Normal Screeding Conditions
A bay joint is required at this position as the total screed area is in excess of 1000m²
Note: If construction joints are present in the base then additional jointing will be necessary.
In areas with large aspect ratios, such as corridors we recommend a maximum bay length of 40m before installation of a construction joint.
We recommends that the maximum bay size when used in conjunction with for underfloor heating is 300m².
Underfloor Heating manufacturers have their own guidelines for the positioning of movement joints within the screed; however it is important to note that a joint should be present between two independent heating circuits to allow for thermal movement within the screed and differential temperature gradients.