ᐅ Dormer significantly narrower and shorter than shown in the building plans.

Hello everyone,

We have recently become homeowners through inheritance and have little experience so far. We noticed that in the attic, especially at the dormer, the actual dimensions differ from those shown in the building documents with the approved permit from the building authority, and we can't find an explanation. Maybe you can help us?

A few details about our semi-detached house:
- Year of construction: 1987
- External dimensions: 5.5 m x 11.5 m (18 ft x 38 ft)
- Gable roof, pitch 35°
- Purlin roof with ridge and eaves purlins plus additional (valley) beam layer
- Knee wall height 0.0 cm (0.0 inches)

Our gable dormer:
- Clear room height 2.5 m (8 ft)
- According to the approved building plan, exterior width 2.5 m (8 ft), interior width 2.0 m (6.5 ft), and interior depth 3.0 m (10 ft)
- In reality, exterior width only 2.0 m (6.5 ft), interior width 1.75 m (5.7 ft), and interior depth only 2.5 m (8 ft)

Could these deviations be for structural reasons, or was the building plan just implemented very creatively at the time?

Legoschloss schrieb:

Are there any reasons, such as structural requirements, for the deviations? Or did someone just take a very creative approach to the building plan back then?

I just consulted my crystal ball and traveled back in time. Unfortunately, the building inspector's spirit didn’t share any insights with me.

Seriously though, what kind of answer are you expecting here? How are we supposed to know what someone did 35 years ago? Maybe it was just poor workmanship. Or maybe they simply changed their mind. Or there could be modifications you don’t know about. Or any number of other possibilities.

And above all, what is this relevant for? Do you want to widen the dormer?

Hangman schrieb:

And above all, what is this relevant for? Are you planning to widen the dormer?

We want to install a dormer on the opposite side as well, but only if the dimensions match those in the building plan. Otherwise, a Velux panoramic triple skylight would probably be more practical, since neither a dining table nor a master bed would fit into a 1.75 m (5 ft 9 in) wide dormer.

We are interested to know whether, for example, with our roof pitch, wider dormers are impossible at all, or if gable dormers can never be wider than 1.75 m (5 ft 9 in) in principle. But would the planning authority have approved the plan in that case at all?

OK, then you will need a building permit / planning permission for the new dormer anyway. You can apply for it with the desired dimensions.

Legoschloss schrieb:

or whether gable dormers with pitched roofs can never be wider than 1.75 meters (5 feet 9 inches) in principle.

It does make a difference whether the replacement spans two or three rafter bays.

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