Cupping in Timber Floor - need advice!

**TimberChris** · 23rd July 2010, 12:33 AM

Hi

I have a problem, have been given scary advice & don't have any expertise - would appreciate any comments/advice - thanks!

6 mths ago I had 106sqm of lovely QLD spotted gum 14mm floorboards professionally laid, sanded and polished. It was laid over existing chipboard, glue trowelled, secret nailed etc. I was very happy. I have noticed over time a corrugated appearance over the entire floor. I now know this is cupping. The installer is shocked at the movement at the amount of movement in 6 months and has advised the following:
* Took moisture readings under the house (house on timber joists & concrete stumps) and they came out at 18 (apparently this is high). Therefore he thinks that since the floor was laid in summer and it is now a wet winter, moisture has gotten under the house, this has been absorbed in the chipboard, gone to the boards and warped them.
* He advised me to get extra circulation vents to reduce moisture. I have looked under the house and it isn't wet, nor musty, but I agree it has a slight damp air.
* He advised me to sand and remove the polish on the boards to release the moisture.
* He also advised me to then remove a middle board out of each room to allieviate the pressure that is being exerted on the floor in case it warps the walls/pops timber etc?!?!
* When all has settled, repair, resand & repolish.
Is this right? It makes sense but this will be a huge expense after just paying for a installed floor. What if I get it all repaired and it then shrinks in summer or rehappens next winter? Should I just get extra vents and see if it settles? Should he have checked underneath, or is it just bad luck when it was dry in summer. He checked the timber before laying so it's moisture level and the chipboard moisture level was acceptable.
A bit shocked, confused and scared to wreck my lovely (but a little wavy) floor!!
Cheers Chris

**minus459** · 23rd July 2010, 04:01 AM

Hi Chris
I'm not an expert by any means, but laying a floor like you describe requires leaving a 6-10mm gap between the outside boards and the wall plate or studs, to allow for expansion and contraction.
I think! I am more than happy to be corrected by experts, or even anyone who knows more than me (not expert

)

undies

**jmaxwell** · 23rd July 2010, 09:33 AM

I would not accept that. What was the MC in the floor boards at the start and what is it now. How wide are the boards anything over 80mm at 14 mm thick can be a problem.Easy for the installer to blame moisture .check with BSA get some else to look at it .

**TimberChris** · 23rd July 2010, 06:02 PM

Thanks for your responses: Yep there is expansion to accomodate this, I have measured 10 boards (85mm each x 14mm) and there is 2 to 3 mm expansion so over 9 meters (in widest point) there is a 31mm approx expansion so it's getting pretty close to the expansion gaps i would say.
I have spoken to the Timber Advisory Centre who says they would leave it alone and get more ventilation and wait and see up to 18 months They said it would have to be extreme to warrant sanding/removing. I also spoke to the timber supplier who initially was skeptical on pulling out boards etc/ thought it could be other problems and would come out and have a look. Since they recommended the installer, when I rang back a couple of hours later it had changed to "take the advice of your layer". So independent advice is hard - who is BSA?
I spoke to the layer who says if I want the problem solved quickly (3 - 6mths) I should follow his advice (sanding/removal) - which of course I should pay for since it isn't his fault the moisture occured. If I don't follow his advice I am left open to a much bigger problem (in his opinion).
Thanks - any feedback is food for thought!
I unfortunately don't remember the MC of the timber when put down - although it was left in the house to aclimatize and checked when put down.

**weisyboy** · 25th July 2010, 01:43 AM

if it checked after it was layed. then it sounds like it was not properly dry.

if it was dry and layed correctly then there should be no problems.

was the under floor waterproofed before the new floor was layed.

**Stopper** · 25th July 2010, 08:01 PM

Hi Timberchris,
try posting this on Renovate Forums in the flooring section. The guys there are real experts that do this sort of stuff all the time. Also take a couple of pics highlighting he problem so that they can guage the extent of the cupping and expansion.

cheers
Steve

**nifty** · 26th July 2010, 01:50 AM

Im going to throw all my chips in and say it was not dry in the first place, as Carl said. I here in WA have to prove the moisture reading of all timber I sell. Get an outside opinion of the moisture reading on the floor and the under floor. And if any floor layer tells you that after a floor is sealed you cant get a proper reading thats BOLLOCKS

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