Oak Solid Wood Flooring Distorted - No Expansion Gap

[ReganAndCarter]

My brother got a builder to refurbish his lounge and lay some oak flooring. The work in the room all seems to be of a high standard, apart from the floor. The work was completed about 4 months ago without problems until now. He has this flooring -

https://www.diy.com/departments/colours-rondo-natural-solid-wood-flooring-1-296-m-/1650211_BQ.prd

The room is south facing and yesterday the sun shining into the room was quite strong. He noticed that the floor in front of the fireplace has distorted and caused a very noticeable hump. New skirtings were fitted at the same time, and it seems like he has left the proper expansion gaps where the floor goes under the skirtings, except for the edge that runs along under the fireplace. The fireplace has no hearth, it's just an opening. There is no skirting running under the fireplace, so the floor goes right up to the wall with no gap. This is obviously the problem.

I went round there today and the hump is still noticeable, despite the fact that it's raining and no sunlight into room. The builder is coming to look tomorrow and says he will cut an expansion gap where floor runs under fireplace and put beading down to cover gap.

Because the hump is still in the floor today when there is no sunlight heating it, is the floor ruined? Will the distortion come out, or once bowed is that it?

Any advice really appreciated.

 

[KenGMac]

ReganAndCarter, good evening.

Looks like your correct in the causation.

Given that the flooring is 18.mm. it may or may not go back down?

I would give the builder an opportunity to rectify by retro-fitting an expansion joint, then await results?

If the above fails? who pays for rectification?

Ken

 

[ReganAndCarter]

Good afternoon, Ken, and thanks for your reply.

I was worried about the 'may or may not' go back down' bit as well. I'm thinking maybe not, as the next day the heat from the sun that caused the warping was no longer there. Maybe if the builder puts an expansion gap in where it should be it will help.

The hump caused by the heat has affected the floor further along, but it's not so bad and only noticeable because the door bottom rubs slightly on floor when it's half open.

As for who pays, by rights it should be the builder. It's a big room and the wood flooring was over £1000 just for materials. The only thing that may focus the builder's mind is that he currently has a quote in with my brother for refurbing the kitchen later in the year. We shall see.

Thanks again for your reply, really appreciated.

 

[foxhole]

Heat from the sun will cause shrinkage , not expansion .
What’s under the floor , timber ?,concrete?,insulation? How is it fixed?

 

[mikeey84]

Heat from the sun will cause shrinkage , not expansion .

Heating wood can make it expand, not shrink. Only shrinks when it dries.

 

[Notch7]

It sounds as though it may have been laid as a floating floor, maybe over screed.

If the tongues were glued, then shinkage may cause buckling if sections around the fireplace have no movement gap.

Usually what happens is that a floating floor expands because it takes on moisture, the floor expands and if there isnt enough space it will buckle as pressure increase.

Solid flooring can lift a grand piano or push out walls, its got huge power. A solid oak floating floor should have the relative humidity kept between 40%-60% and reasonablly narrow temperature range. Should never be liaid over new screed

You say the floor is buckling: are the boards lifting off the ground because theyve expanded, or have individual boards twisted or cupped badly causing a section to lift.

 

[Deleted member 174758]

Heating wood can make it expand, not shrink. Only shrinks when it dries.

Unless the RH is really high heating wood will dry it out, so it will tend to shrink, just as Foxhole states

I'm leaning towards the screed having not been dried out sufficiently or the timber having gone in without expansion gapping in the first instance. How old was the screed? Was it ever exposed to the weather outside, and when? And did the floor layers put-in either a plastic or liquid (normally green) DPM?

My feeling about sections of flooring that have lifted is that they are cream crackered and should be replaced rather than any attempt being made to re-use them. Surely any sensible contractor would do this to minimise the chances of future call backs

 

[mikeey84]

Unless the RH is really high heating wood will dry it out, so it will tend to shrink, just as Foxhole states

But direct sunlight will heat it up very quickly without drying it that much, therefore it will expand.

 

[Notch7]

But direct sunlight will heat it up very quickly without drying it that much, therefore it will expand.

Thermal expansivity of oak is in the order of 0.000003

Expansion and contraction due to change moisture content is much greater.

Also timber expands and contracts twice as much tangentially than radially, hence why floorboards cup.

Ideally flooring should be laid with a smiley face so each board crowns as it dries.

 

[mikeey84]

Thermal expansivity of oak is in the order of 0.000003

Expansion and contraction due to change moisture content is much greater.

Also timber expands and contracts twice as much tangentially than radially, hence why floorboards cup.

Ideally flooring should be laid with a smiley face so each board crowns as it dries.

I'm not disputing that expansion due to moisture level is much greater, but the fact remains that oak does expand due to purely thermal changes.

 

[Notch7]

I'm not disputing that expansion due to moisture level is much greater, but the fact remains that oak does expand due to purely thermal changes.

Ive only ever seen timber shrink due to sun light exposure -because any thermal expansion is much less than the mc change shrinkage.

certainly almost all materials expand with increase in temperature (not water between 1 to 4 deg....), but I think the the cell structure of timber is more complex than the simple expansion of molecules of a homogenous material like plastic or metal.

 

[mikeey84]

You are certainly right in regards to complexity of wood Vs metal or plastic, but surely sunlight on a damp wooden floor would heat it before it dries out completely. Wood takes an awfully long time to dry, and would be warm and wet long before it's warm and dry.

Anyway, for the OPs issue, it's probably not just sunlight that's causing the issue unless they have a really really long/wide room