Green Building Forum - Part L and external doors

Part L and external doors

Johan — Wed, 15 Aug 2007 14:21:01 +0100

I'm a bit confused about the thermal performance for external doors.

If I've read the part L regulation correctly you need to use doors with better a u-value then 2.2W/m2K IF they have more then 50% glazing. Other doors it stats u-value <3.0W/m2K. Is this correct??

Sounds a bit mad to me! A door without a window should easily achieve less the 1.0W/m2K with a PUR core...

You also don't need building regs/FENSA cert. to fit a <50% glazed door as I understand it. Is this correct?

Anyone who can help clear up my confusion? Many thanks.

Part L and external doors

tony — Wed, 15 Aug 2007 14:30:50 +0100

Its all mad you are right!

Part L and external doors

biffvernon — Wed, 15 Aug 2007 20:24:27 +0100

It may sound a bit daft at first glance but it's the pragmatic approach to the fact that it's difficult to get a low U-value with solid wooden doors. There are plenty of reasons why solid wooden doors are better than the horrid things with PUR cores.

I made an oak panelled door recently with the panels comprising two half inch layers of timber separated by an insulating foam layer.

Part L and external doors

Johan — Wed, 15 Aug 2007 21:49:25 +0100

Biff, do you mind elaborating a bit on that? It what sense is a solid door better?

I wasn't talking about uPVC doors...there is nothing good with them...
I ment timber doors with a PUR core for better insulation performance.

I can see that a solid door may be 'greener' in the sense there are no oil derivatives, but performancewise a door with an insulated core will be better. Don't you agree?

Besides if you really, really don't want PUR there are also a few Scandinavian and German timber door manufacturers using woodfibre cores for the insulation (similar to pavatex) achieving u-values of <1.5W/m2K, which is substantially better then a solid door!

Part L and external doors

biffvernon — Wed, 15 Aug 2007 22:31:39 +0100

I've not seen a wooden door with a PUR filling. Aerogel would be even better. Steel faced doors sometimes have PUR fill.

Part L and external doors

Johan — Thu, 16 Aug 2007 09:26:18 +0100

biff,

Here's a few manufacturers of timber doors with a PUR core all available on the UK market: Dooria, Diplomat, Ekstrand

Here's one using a pavatex type core: Swedoor (part of Vest-Wood)

There are several others.

Anyway, I think I got my question answered. I can fit a new front door myself!

Part L and external doors

biffvernon — Thu, 16 Aug 2007 14:22:16 +0100

Dooria are, I think, composites of wood veneer, aluminium and styrofoam.
Swedoor are similar, inloving aluminium sheets.
Ekstrand are made of stuff that could hardly be recognised as coming from a tree.
Dunno about Diplomat.

Are there any high performing doors that look like they are made of wood, perhaps because they actually are made of wood?

Part L and external doors

Johan — Thu, 16 Aug 2007 15:24:58 +0100

Yes, Sauna doors!