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Due to a conflict with a newly-appointed fire inspector citing previously unnoticed violations of safety margins of a chimney construction in a house in Germany/Brandenburg, I had the pleasure to conduct a cursory research of the current fire safety codes (link in German).

The problem cited is that apparently one joists(?) from the roof construction lies slightly (1cm?) within the safety margin of 5cm of the chimney. It wasn't ever an issue on any inspection in the past, and there have been multiple inspections. Obviously, it is not an option to move either the chimney or the roof, and thus, resolving this issue is not trivial.

There is an option of contradicting the finding, but we need a good argument if we try this. My research of applicable codes indicates that 5 cm is always neccesary for walls, panels et cetera, which cover a significant portion of the surface, so the finding is not totally bogus.

However, there is a clause that exempts joists and other beams, for which only a distance of 2 centimeters from the chimney is required.

zu Holzbalken und Bauteilen entsprechender Abmessungen ein Mindestabstand von 2 cm ausreichend und zu Bauteilen mit geringer Fläche wie Fußleisten und Dachlatten, soweit die Ableitung der Wärme aus diesen Bauteilen nicht durch Wärmedämmung behindert wird, kein Mindestabstand erforderlich.

Translated loosely, this means...

A margin of 2cm is sufficient for joists and elements of similar dimensions No margin is required to elements of limited size such as Baseboards and Battens (google translated: Fußleisten und Dachlatten) as long as heat dispersion is not inhibited by insulation.

Upon request, the inspector replied that the beam was too large to be considered exempt, but would not offer a source. I understand there must be some place where the maximum dimension of such beams is defined, but it does not appear anywhere in the building code (at least not the relevant part I've linked above).

Thus my question is, where do I find the (size-) limits of beams. Is it some general building code, or ist there something like a DIN-standard? By chance, I do have access to the catalogue, but would need more pointers on where to look.

Also, any tips on how to deal with the issue in a constructive manner (fire-proofing?) would also be greatly appreciated, as the instructions given by the inspector were very unspecific ("Has to be dealt with by a specialized contractor" - which we are definitly willing to do, unless it means moving the attic.)

Thanks in advance!

Also, caveat, I used google translate several times, please let me know if you notice any mistranslations.

antipattern
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  • For joists/beams there is a minimum size listed for the load and span that the joist can safely hold. Larger sizes usually not used just because of cost. Usually with minimum distance to hot surfaces, there usually is a way to protect a flammable material if it must be closer than minimum safe distance. – crip659 Aug 27 '21 at 12:35
  • battens are small timbers sometimes used to attach surface sheeting to masonry, joists, and rafters. so it sounds like a good translation. – Jasen Aug 27 '21 at 12:49
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    While it's always possible that you'll get a good answer here (I'm often shocked at the breadth of knowledge exhibited by members of this stack), I'd suggest that you contact a local contractor and/or lawyer to help you with this. They'll have much more intimate knowledge of the code and be able to help you defend your existing installation (for example, if there was a change in code in the US, existing things aren't required to be changed to meet it), or guide you to options to meet the code without having to do major construction (like installing appropriate insulation/fire block). – FreeMan Aug 27 '21 at 13:03
  • It could be that the code is for structural members, and that will have no size requirements. If it holds something up and burns, it is bad. If it is a cosmetic feature, or non structural such as base or battens then there is no concern. Suggest to the inspector if it is possible to slip a piece of metal between the wood and chimney to isolate the material. – Jack Aug 27 '21 at 13:27
  • Thanks for the input everyone. The joist is part of the floor structure of the roof and probably serves as a structural member as well. The architect told that carving the joist is not an option and moving the chimney is not feasible either (I dont currently know the exact reason). Adding insulation is a thought I already had suggested but the inspector did not give any feedback beside what I wrote above and did not yet respond to further inquiries. I understand that a contractor must be hired after all, but it is hard to get a good quote without understanding the issue first. – antipattern Aug 27 '21 at 14:35
  • Food for thought: What is the material of the chimney? Are there requirements as to its internal cross section and wall thickness? If it's ductile like a sheet metal pipe it might be flattened/compressed on the one side to gain 1 cm of clearance. If it's masonry the exterior wall might be ground thinner. Also, there surely must be a possibility to convert at least a section of chimney to materials that allow zero clearance. – Greg Hill Aug 27 '21 at 16:30
  • Will the chimney be used for an open fire, or could a metal flue be inserted? – Tim Aug 28 '21 at 10:50
  • @GregHill Thats unfortunately not possible, the chimney is a metal pipe inside a rectangular shaft built with some kind of heat resistant brick (no idea what exactly) – antipattern Aug 31 '21 at 09:39

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I get the feeling that the problem is that the joist is part of the buildings main structure rather than being part of the buildings surface.

to satisfy the inspector you will probably have to move the joist or the chimney.

It may be possible to carve the joust back so that it is 2cm away from the chimney and then reimforce the now weakened joist to restore its original strength. conversely if the chimney bricks are thick enough it may be possible to thin the one near joist to imoprove the gap - you'll have to check the building code.

Jasen
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  • Thanks for your answer. The joist being a structural member may change requirements, that does seem plausible. The wording of the code does not make that differentiation, but that's proabably beyond my knowledge. If nothing else works, I will check with the architect if carving back and reinforcing the beam might be an option after all. – antipattern Aug 27 '21 at 14:41