Christa Campbell has a good building site for a passive solar home, and she’s planning on laying tile over a concrete slab for the finished floor. An “uncoupling membrane” used between the concrete and tile, such as Schluter’s Ditra, is designed to keep any cracks that develop in the concrete from telegraphing into the tile and grout.
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But, Campbell wonders in a Q&A post at GreenBuildingAdvisor, will the membrane insulate the tile from the concrete and lower the potential for the slab to absorb and store thermal energy?
Answers to that question, the topic of this week’s Q&A Spotlight, offer a range of advice. While some posts argue that uncoupling membranes are really designed for use over lightweight wood subfloors, not concrete, others claim that concrete’s tendency to develop cracks as it cures makes a good argument for using a membrane here.
A compromise would be to use strips of membrane only over control joints or cracks, a strategy that provides the benefits but at a lower expense. GBA advisor Michael Chandler explains.
Read the whole article at Green Building Advisor
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Keeping cracks in check Applying strips of uncoupling membrane between a concrete slab and a tile floor can help prevent cracks in the slab from affecting the finished surface
View Comments
I am concerned that the Ditra is applied only over an existing crack. Here in Ontario north of Toronto we do lots of this stuff and though the Ditra is expensive (about C$ 2.00 psf) it is actually cheap insurance which will ensure that the entire floor will remain crack free indefinitely.
Woodcutter, I am concerned that the Ditra might be overused and unnecessarily raising the cost of using tile. I totally can see it's benefit in problem areas but is it really necessary on prefectly good substrates?
I have seen tiles and grout crack where Ditra has been used. On the same job I saw tiles move. This may be due to improper installation, however it was professionally done. 2 sheets of 5/8 ply always works well (if possible)
Seems like a heavy poly sheet then 5/8" plywood is good insurance.