I believe it is actually narrower and shorter than in the construction drawing.

Hello everyone,

we have become homeowners for the first time through inheritance and still have little knowledge. We noticed that in the attic, especially at the dormer, the actual measurements differ from those in the construction documents with the building authority’s approval stamp, and we find no explanation. Maybe you can help us?

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

Our gable dormer:
- clear room height 2.5 m
- according to approved construction plan outside 2.5 m and inside 2.0 m wide and (inside) 3.0 m deep
- in reality outside only 2.0 m and inside 1.75 m wide and (inside) only 2.5 m deep

Are there, for example, structural reasons for the deviations or did someone simply implement the construction plan very creatively back then?

Are there, for example, static reasons for the deviations, or did someone back then just interpret the building plan very creatively?

I just stroked my crystal ball and traveled to the past. However, the spirit of the building authority clerk told me nothing there. Seriously. What kind of answer do you expect here to your questions? How are we supposed to know what someone did 35 years ago? Maybe it’s just shoddy workmanship. Or someone simply changed their mind. Or there are changes you don’t know about. Or or or.

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

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

We also want to have a dormer installed on the opposite side, but only if the dimensions correspond to those in the building plan. Otherwise, a Velux panorama triple window would probably be more practical, since neither a dining table nor a parents' bed etc. would fit into a 1.75 m wide dormer.

We are interested here in whether, for example, no wider dormers are possible with our roof pitch at all, or whether gable dormers can never be wider than 1.75 m as a rule. But would the building authority have even approved the plan then?

OK, then you will need a building permit for the new dormer anyway. And you can have it applied for with the desired dimensions.

or whether gable dormers can in principle never be wider than 1.75 m.

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