Esmé Eloff of Midrand asks
We want a screed floor but we want to lay it over our existing tiles. I believe there are products suitable for this; any suggestions?
Karin Cronjé of Hands on Creative Building and Management answers
I’ve tested a wide variety of products for this purpose and all of them have been unsuccessful. Spreading a thin layer of screed over tiles can go wrong for many reasons. If it’s an old house with no damp-proof course (DPC) under the concrete slab, watermarks will show through. These sporadic dark spots will spoil the look of your floor – especially if the screed layer on top of the tiles is sealed with an epoxy sealant; the moisture has nowhere to go and won’t be able to evaporate.
The other possibility is that the tiles over which you want to lay the screed might be loose in places, which will result in the new thin layer (3 to 6mm) of screed cracking and eventually crumbling. The third potential problem is that the grouting between the tiles will probably be a darker colour than the rest of the floor and this will show through and become unsightly. In addition, because the layer of screed is so thin, it’s nearly impossible to get the two products to adhere successfully.
To get the beautiful screed floors you desire, it’s best to remove all the tiles and prepare your floor surface well. Although this is a more expensive option, it’s really the only way to go.
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