The query you have mentioned is related to waterproofing works.
As you may be aware that in waterproofing works the first layer of protection is by doing the BASE COAT.
BASECOAT- This can be either a cementitious layer or a chemical coat layer, nowadays for better protection from waterproofing works at say the podiums, driveways, and terraces chemical coatings are preferred which range from a acrylic coating to polyurethane coatings, so once this coating is applied in order to protect the coating from damages and simultaneously for proper drainage of the stormwater ( rains) either we use brickbat coba or a screed concrete.
Brickbat Coba also works to give heat insulation and slope which works out cheaper to concrete screed, however wherever there is heavy traffic movement then the brickbat coba cannot be used due to lower compressive strength and hence concrete screed of at least 3" to 4" min thickness can be provided.
It its a driveway then the same screed can be substituted with STAMPING which will save in cost if you are going to used CHEQUERED TILES as the final finish for the driveway.
If its a non-trafficable area then you can make use of BRICK BAT COBA which will be cost-effective.
Now in your case you are mentioning for TERRACE, so if there is no traffic on the terrace then you can go for BRICK BAT COBA as compared to CONCRETE SCREED due to following reasons:
- Brickbat coba average thickness req in residential buildings is 115mm so less load on the structure as compared to concrete
- Brickbat coba is cost-effective as compared to the concrete screed.
- Heat insulation properties much better as compared to concrete screed
- Less cracking of surface as compared to concrete screed
- Brickbat coba is time-consuming as compared to concrete screed which can be laid and finished in half the time of brickbat coba.
- Brickbat coba is time tested and hence the better product, however it will again depend to type of application.