Bi Fold doors


30 Jan 2019
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United Kingdom

We bought a new build with BI fold doors. The bi fold doors have an outer aluminium frame. The frame is covered in condensation at the bottom and at just the bottom 1/5th on the sides. They are manufactured by ALUK, they installer has been out 3 times now the latest was yesterday where they removed the silicon to confirm the frame is not on the masonary. I didn't see myself, but the confirmed not. They then resealed around the frame. The frame is still covered in condensation yesterday and today after the visit though, sometimes i have to wipe it 3 times a day.

The frame has a thermal break, but its so cold at the bottom. For example yesterday it was 20C in the room (heating on), the windows were around 17C, the window frames the same, but the outer aluminium frame was around 8C at the bottom.

The fitters say they have raised it with ALUK and we are awaiting the outcome/site visit. But they all just seem to be fobbing us off advising its condensation. The issue i have with this is that we have a humidty sensor (TADO sensors on the TRVs) These record the humidity throughout the day and it varies between 41 and 53% at the highest over several days.

I'm just looking for advise really as we can't have a wet frame all the time or mould will form. Has anyone any experience of this? The windows never have condensation on them, just the outer frame. Also all the houses in the cul de sac have the same windows, but none have this issue. Just looking for some ideas on what to do next as I have no knowledge on this subject.
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Here are some photos. Let me know if I can provide better angles


It’s a new build and was installed when built last summer.

The installation company sent me the following info in an email with the attached picture:

“Thermal break, as advised, all our frames are thermally broken, the inside and outside metal are connected by a polyamide connection, please see below cross section showing the outer frame installed in your property”

I’m at work at moment, but could take a look further and some pictures inside the frame. Not sure on screws. I am right in thinking though that modern frames with a thermal break shouldn’t be getting into single digits in temp (c) when inside is around 19/20C and causing condensation to form though aren’t I?
Yeah I’ve asked 4 of the neighbours and none have this issue with the doors.

Anyone any ideas of anything I could check or suggest is the issue to the builder or installer?

Is it possible the thermal break isn’t working?
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I’ve just had details on the installer visit yesterday through (below) plus photos.

“Dan who called yeterday, removed the silicone on the bottom/side to check if doors were sat directly on the masonary, he did confirm this was not the case, the doors ahave a timber pack all the way around wich isolites the frame from the structure.
He did identify the stone cills have a gap between them which goes under the door threshold which would affect the thermal efficiency of the door (photos attached)”


Do you think this could be the issue? Does this answer the foam question?
In your second picture looks like the skirting board is starting to get wet/damp, and the oak floor looks like it's got a dark stain... could water be getting in, in the corner?
Does anyone know how a stone cill should be insulated inside? Maybe this is just acting as a thermal bridge to the inside. Its currently 20C in this room, the windows and frames are 15/16C, but the outer aluminimum frame is 5.3C and has condenstation all across the bottom and a little at the sides(bottom 1/5th). Humidity is currently 39% in the room. The builder is saying its the installers and the installers are saying its fitted correctly. The installer has arrange a site visit from the manufacturuer next week, but not sure what they will do about the situation. I suppose unltimately its the builder's responsibility for the house so he should take ownership. Its like pulling teeth to get any traction though. We've been at this since Oct when the weather changed.

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