# Birch ply warping/ underfloor heating.



## Guy Cherry (14 Jul 2021)

Hi recently I had some floor level birch ply cabinet doors warp badly. The room had underfloor heating turned up quite high.

I made replacements but these warped as well.
Have other people had similar effects from underfloor heating and birch ply? 
Thanks


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## robgul (14 Jul 2021)

How thick is the plywood? - and what grade/how many plies are there?

I've had 12mm ply warp, although not with underfloor heating - possibly just slightly lower grade ply? The other issue is, if the plywood is finished, differing number of coats on front and back (this happened to me, again with 12mm, and paint finishes.


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## Daniel2 (14 Jul 2021)

Yes, I've heard of that phenomenon before.
Differing levels of finish, front to back, leading to warping.


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## Guy Cherry (14 Jul 2021)

robgul said:


> How thick is the plywood? - and what grade/how many plies are there?
> 
> I've had 12mm ply warp, although not with underfloor heating - possibly just slightly lower grade ply? The other issue is, if the plywood is finished, differing number of coats on front and back (this happened to me, again with 12mm, and paint finishes.


Hi it was 18mm birch ply b/bb grade finished both sides with osmo. 
I ask because I’m quoting for a lot of birch ply cabinetry in a house with underfloor heating.


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## robgul (14 Jul 2021)

Guy Cherry said:


> Hi it was 18mm birch ply b/bb grade finished both sides with osmo.
> I ask because I’m quoting for a lot of birch ply cabinetry in a house with underfloor heating.



I think I'd ask one of the very high end "designer plywood" user businesses if they have any experience - and perhaps one of the quality plywood suppliers (cutlist.co.uk may have some thoughts - they, obviously, supply precision cut top quality plywood to all sorts of users)


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## Rorton (14 Jul 2021)

Were they solid birch ply doors or rail and style doors?


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## Doug71 (14 Jul 2021)

How big are the doors?

I always think cupboard doors like that can bend because the conditions inside the cupboard are different to the conditions outside the cupboard so you are bound to get an imbalance.


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## doctor Bob (14 Jul 2021)

does the sun shine on them?


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## Peter Sefton (14 Jul 2021)

Birch ply has a life of its own, I would use MDF veneered and lipped if possible.


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## Sgian Dubh (14 Jul 2021)

It's sometimes said the expression 'flat plywood' is an oxymoron, that the two words don't belong together in a sentence. It's not always the case, in fact it's quite rare, for plywood used as slab type doors to warp, but it does happen sometimes. I have made quite a few cabinets over the years with such doors, some quite high end with lipping, and some simpler ones for tool cabinets and the like, and most of them have stayed flat, or if not flat, have developed almost imperceptible warp that needed no correction or replacement. But every now and then I've experienced such doors or other unrestrained panels that did decide to warp badly, which is darned annoying because they eat into time to effect a repair, correction or, worst of all, replacement fee of charge. Slainte.


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## Distinterior (14 Jul 2021)

If I'm ever designing and installing a kitchen in a new build property, I always stipulate that no under floor heating is to be installed directly under where any of my cabinets are going to be fitted.
I did install one once as I was invited to quote for the job a long time after the under floor heating and tiles had been fitted. I did state in my quote that I would accept no responsibility for any distortion of the cabinet or cabinet doors due to the proximity of the under floor heating coils.......About 3 months after the customer moved in, they rang to say the doors had started to twist....I referred them to my original quote and have heard nothing from them since.


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## Spectric (15 Jul 2021)

If you read many of the installation details for the various suppliers of UFH they all show the coils placed in the areas not covered by cabinets and fitted units, it is pointless putting heat in these places.


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## chris.gid (15 Jul 2021)

I've had 18mm birch ply full height wardrobe doors warp by about the thickness of the ply. Annoyingly the door on the left is warped out at the bottom and door on the right it warped out at the top so looks terrible, thats without underfloor heating. 
Next time i'll make the doors from 12mm MR-MDF and then face the front in 6mm birch ply.


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## Spectric (15 Jul 2021)

Is Birch ply no longer what it used to be, are people finding it is not as good as it once was or is it being used / assembled in a different way? No expert on doors, but having read many books the one thing they seem to agree on is the panel is loose within the frame so it can move, things normaly warp when they change size but are restricted, something you learn in welding.


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## owen (15 Jul 2021)

Spectric said:


> If you read many of the installation details for the various suppliers of UFH they all show the coils placed in the areas not covered by cabinets and fitted units, it is pointless putting heat in these places.



Only pointless if that is 100% the place where the units will be forever, the ufh will more than likely outlast the kitchen cabinets, and people like to change their houses around so having it installed under the cabinets means you don't get any cold spots when thing get altered. I've never had any problems with it being under the units.


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## Spectric (15 Jul 2021)

Often the kitchen layout is dictated by the shape of the room so the cabinet runs will often only go on certain walls, if doing a major then just start with a blank canvas, would you want to install say a twenty grand kitchen on fifteen year old UFH pipes that you don't know who or how they were fitted. Ok so if done right these pipes last with no issues, but what about the ones with bad kinks, twisted pipes and yes, joints.


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## recipio (15 Jul 2021)

Baltic Birch Ply is a favourite of designers for that Scandinavian look but I wouldn't make large doors out of it as I've never seen a panel stay dead flat. A bit late now but I think I would use blockboard veneered with Birch veneer which is available . It could be lipped with Baltic ply to preserve those attractive edges.


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## owen (15 Jul 2021)

Spectric said:


> Often the kitchen layout is dictated by the shape of the room so the cabinet runs will often only go on certain walls, if doing a major then just start with a blank canvas, would you want to install say a twenty grand kitchen on fifteen year old UFH pipes that you don't know who or how they were fitted. Ok so if done right these pipes last with no issues, but what about the ones with bad kinks, twisted pipes and yes, joints.



I agree but people change their mind on things just for fun. If the underfloor heating is fitted properly, there will be no joints under the floor, no kinks or twisted pipes either. I'm talking proper underfloor heating under a screeded floor not a overlay system, it would be a massive job to rip out and replace.


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## cowie122 (16 Jul 2021)

chris.gid said:


> I've had 18mm birch ply full height wardrobe doors warp by about the thickness of the ply. Annoyingly the door on the left is warped out at the bottom and door on the right it warped out at the top so looks terrible, thats without underfloor heating.
> Next time i'll make the doors from 12mm MR-MDF and then face the front in 6mm birch ply.


You need to balance the door or it will bend ie ply to both faces


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## Guy Cherry (16 Jul 2021)

robgul said:


> I think I'd ask one of the very high end "designer plywood" user businesses if they have any experience - and perhaps one of the quality plywood suppliers (cutlist.co.uk may have some thoughts - they, obviously, supply precision cut top quality plywood to all sorts of users)


I’ll try that thanks.


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