Insulated Internal Doors

Jaith

We are arranging to move to an air source heat pump. The house is generally well insulated but has an unheated conservatory which we don't use when it's cold. One of the conditions is that we replace the current doors from the house to the conservatory, which are wood/single-glazed glass pane french doors, swapping for an 'external grade door'. This is because the current doors leak a huge amount of heat.

I am looking into double glazed UPVC french doors, which would work, but they're unnecessarily bulky, have security- and weather-proof features we don't need and would cost around £1500 all in. I have done a little research into insulated interior doors but there doesn't seem to be much of a market for it, and what I've found is all solid wood whereas we want something glazed to let the light in.

Does anybody have any suggestions, or will I just have to accept going with external-type french doors?

Ectophile

If it's a standard conservatory, then it won't meet building regulations and isn't considered part of the house.  It's a glorified lean-to greenhouse.  In that case, you are supposed to fit external doors between the house and the conservatory.

Reed_Richards

I suspect the exterior doors to your conservatory aren't particularly secure.  Therefore you might benefit from the security features on the UPVC doors that you have looked at - provided you remember to use them.

Martyn1981

Is it a rule/requirement that you have to install exterior quality doors, or is it that your current doors, simply aren't good enough .... but could be improved?

I ask, as I replaced all of the single pane glass between our tiny conservatory and living room with DG units. Six in total, 3 smaller overhead pieces (approx 700mm by 450mm), and 3 'door' pieces (approx 1,000mm by 450mm). I ordered the DG panels from a glazing company, and installed them into the existing wooden frames, using quadrant moulding (just an example). [24 corners (requiring 48 pieces) and not a single one was 90d ]

I was able to find 14mm DG panels, which just about fitted into the original wooden doors. [Edit - very rough guess, probably about £100-£150/m2.]

But, if there are rules and regs on this, then a DIY approach, with thinner (less efficient) DG units, may not be acceptable?

Jaith

Thanks for the replies. Yes I was of the understanding that regs required external doors. Our conservatory was in the 2000's before we bought the house, it had planning permission so either they swapped the doors out afterwards (which as I understand is not illegal, kind of a loophole) or the regs were different back then.

Martyn1981 said:

Is it a rule/requirement that you have to install exterior quality doors, or is it that your current doors, simply aren't good enough .... but could be improved?

Good point, and I'm trying to clarify that with the installer now. I think the 'must have external grade doors' is simply an MCS (certification scheme) standard requirement, but ultimately it's just about the room acheiving sufficient thermal standard that it won't stuggle to heat in cold weather. I'm looking for bespoke internal doors with double glazed glass, but no luck so far. Someone else suggested what you've done, we have georgian style lattice so 12 panes per door, it'll be a pain but should be possible! We already have spare heating capacity even at the 50C heat pump design temperature, so I'm hoping the installer will accept this as being sufficient.

Martyn1981

Best of luck.

Not sure this helps, as it's building regs, not heat assessment rules, but we had a side extension built on our house. As it was to be unheated, building regs required external quality doors which opened to the front drive and rear garden, or on the door from the 'garage' into the house. But we didn't have to do both, so it was signed off before the internal door was installed, as the outer doors where external standard. We did actually have an external DG door for the inner door, just for better efficiency, and security.

If we'd put more basic doors to the outside, then the 'garage' would have been classed as an outside space, hence the need for the inner door to be external grade.

We did also fully insulate (floor, walls and ceiling), which also wasn't required for building regs (for an un-heated room), but I can't recall if that impacted the inner door - I don't think it did, so long as the walls weren't single, and had a cavity.


Edit - Just a thought, from what you've described, those glass panels may be held in by moulding on the inside (outside, probably part of the door). So you might be able to pop them out, and re-install closer to the edge, if there's enough lip.

If not enough space/lip, then smaller trim/quadrant, with a whole load of veneer pins (smaller than panel pins) might do it. Note - smaller trim might not cover the silver foil around the edge of the DG, so you will need to hide. I used a thin border of black car striping tape.

But may not be worth all the effort, as the cost per DG unit will be much higher (proportionately) for smaller pieces. Sorry.

QrizB

Martyn1981 said:

Not sure this helps, as it's building regs ...

That was my thought, too. Building regs (I don't think planning & permitted development comes into it, but I could be wrong).

Conservatories get away with being built to lower standards by virtue of not being habitable spaces (there's probably a specific technical term but I don't know it). They are outside the house proper, which means you have to keep an external door between the house and the conservatory - and external doors have to meet their own Part L building regs requirements.

If you take this door away, the conservatory needs to fully compll with the building regs, and generally they don't.