Large Timber Door Bowing - Whats gone wrong?

[katies]

Large Timber Door Bowing - What's gone wrong?
Could do with some expert advice please to see if this can be remedied on a replacement.
The door is 1.1 meters wide approx, the construction is (I'm told) engineered hardwood solid core door (44mm) with 6mm tricoya face, the back is also faced with 6mm Tricoya (the inside face is white).
The 3 wide grooves running along the top are 6mm deep (so down to the hardwood door beneath the tricoya). The bottom lines are western red cedar which are glued into the same style grooves shown at the top. There are also grooves on the inside face the same depth but in a vertical direction.
The picture shows a gap at the top corner (it is also the same at the bottom, neither corners of the lock side touch the draft seals) the door was shut when this was taken so it's around a 5mm gap/bow at the top and bottom. This started to happen within 2 months of the install, is was end November at the time of installation.
The manufacturer is 'potentially' willing to replace it but can't say why it's happened and will not guarantee a replacement from doing it again.
The door has been in situ for a year now, the summer months get sunshine on this from 2pm onwards, in the summer it went flatter (not fully back but better than it is now)
It's a bit puzzling as to what's gone wrong and how it can be avoided.
Any thoughts?
TIA

 

[Notch7]

I would say the external side of the door has expanded due to an increase in humidity compared to the inside face

the tension created by that has led to the opening side bowing inwards top and bottom

In my experience tricoya doesnt change much in size as it doesnt absorb much moisture -a 9mm piece of tricoya mdf put in a bucket of water will only expand by about 0.2mm over a week and not really change much beyond that

So my best guess is that the moisture has got through where the machined out detailing is and increased the moisture content in the solid wood core door structure


external doors have to cope with a fair bit of stress because the external face is subjected to a large range of temperature andr/ humidity up to almost 100% and the internal face is subjected to central heating with a temperature of around 15-20deg and a R humidity around 40-60%

I would say that external doors painted in dark colours get extremely hot if they get sun on them in the summer and this can cause warping and stress -ask anybody with a rosewood upvc front door that gets full sun.

 

[katies]

Thank you for your thoughts Notch7.

This was my thought as well, however, having had the manufacturer come out and examine the door they could not find any evidence of any paintwork cracking, they use technos paint on the outside. They could not find how any moisture could have gotten into the engineered wood door (can it get though paint?). The other thing, which I don’t fully understand, the outside of the door being black, absorbing all of that heat in the afternoon sun in the summer, did straighten the door very slightly, where I would’ve thought it would have gotten worse? I suggested to the manufacturer that were they to replace the door they would need to face the door with at least 12 mm (They originally quoted me for 18 mm with oak core) and then route the grooves into that so it goes nowhere near the surface/structure beneath). They said that they would not route into 18 mm tricoya, as the surface goes very ‘furry’ and requires more finishing. Do you have any experience with routing into Tricia? from what I can gather it isn’t a furry surface that’s created like it is on MDF for example.

 

[pcaouolte]

Do you have any experience with routing into Tricia? from what I can gather it isn’t a furry surface that’s created like it is on MDF for example.

Tricoya is MDF. It machines in much the same way as any other MDF.

 

[katies]

Tricoya is MDF. It machines in much the same way as any other MDF.

Thank you, never used it so only from reading up about it was I led to believe it had different properties and characteristics. MDF, as you know contains both softwood and hardwood fires. Reading some of the bumph on the tricoya website suggest that by only using Acoya wood fibres and treating them in a specialist way the material itself has different physical properties and characteristics to regular MDF.

 

[freddiemercurystwin]

Tricoya is MDF. It machines in much the same way as any other MDF.

Yes but I thought one of the advantages of tricoya was that it does not fur when cut.

 

[Notch7]

Thank you, never used it so only from reading up about it was I led to believe it had different properties and characteristics. MDF, as you know contains both softwood and hardwood fires. Reading some of the bumph on the tricoya website suggest that by only using Acoya wood fibres and treating them in a specialist way the material itself has different physical properties and characteristics to regular MDF.

tricoya is simply wood fibres which have gone through the accoya acetylation process, then compressed into mdf sheets

acetylation: -reaction of wood with acetic anhydride, concentrated acetic acid at high temperature to increase level of moisture resistant acetyl groups acid (in simple terms, pickled in vinegar)

 

[Notch7]

Yes but I thought one of the advantages of tricoya was that it does not fur when cut.

Im not sure the accoya process has anything to do with that per se, maybe more to do with the timber used to make accoya and the density of the mdf when bonded

In my experience tricoya is ok for machining but not amazing

furry mdf is usually a sign of cheap mdf bought from a local builders merchants.

Quality mdf like medite are smoother and the smoothest mdf for painting is moisture resistant especially Finsa hidrofugo (fantastic for making shaker doors for painting)

 

[katies]

Do you think painting a replacement a light colour would stop this happening? I really don’t want to do that for aesthetic reasons however. Cedar clad front?

 

[freddiemercurystwin]

What have you to lose ....