Bowing engineered flooring

7 Oct 2013
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United Kingdom

We have recently had an extension built and had engineered brushed and oiled oak flooring laid down by our builders. Part of it is over the existing rooms flooring boards and the new extension part is on concrete.

We told the builders that engineered flooring can't be laid down till the concrete is fully dry (can take a month) but they said it would be fine as they put some kind of sealant over it before laying down the high performance underlay.

We have now had the flooring start to bow and raise in places. We asked if they put in sufficient expansion space for movement under the skirting which they said they did.

We assume its bowed because either the concrete is not fully dry or because it doesn't have sufficient expansion gaps. We are getting the builder back our to look at.

My question is, what is the best way to solve the problem? Does the whole floor need to come up or can they fix the bits that are raised? We have about 4 packs of flooring left, so could use those to replace some boards if needed.

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Well ive not heard that one before.

as far as i know you have to let the concrete sub floor dry completely before laying the engineered flooring, usually 10mm per week.

sounds like your builder has pulled a fast one.

could possibly repair parts of the floor? depends if it has been glued together. unlikely if thats the case. hopefully someone with more knowledge than me can confirm.
Thanks - we thought so too which is what we told the builder. We have them coming out this weekend to review.
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Why let a builder lay your floor?

The drying rate is 1mm per day for the first 25mm then longer for the rest.
He should of laid a liquid dpm on top of the concrete.
How much expansion gap did he leave.

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