Professionally build a dormer yourself

Dormers are attractive, practical and give a house a completely new look. But the construction of a dormer is not without problems. The following instructions for self-construction of a dormer should really be used only by experienced DIYers.

The professional planning of a dormer is elementary

First of all, the practical benefits of dormers are in the foreground. This will give you natural daylight even in the converted attic. In addition, however, the visual effect of the house from the outside is important and crucial. So a dormer should be large enough to guide sufficient light into the attic, on the other hand, it must not dominate the house and the roof too much.

Types of dormers

  • Gable and triangular dormers
  • Towing and flat roof dormers
  • trapezoidal dormers
  • Spitz dormers
  • Hawk and cripple whale dormers
  • round dormers
  • Bat and ox dormers

The dormer designs can also be distinguished by the fact that in certain constructions there are no dormer jaws. Depending on the cost of materials and size, the different dormers also vary greatly in cost.

Professionally build a dormer yourself: build

Build the dormer completely yourself or use a kit

Many dormer forms you do not have to build completely yourself. So you can proceed differently if you want to build your dorm yourself. For example, in the case of bat gulls with curved wedge boards or standard dormers, the choice may be advantageous for you:

  • Build the dormer completely yourself
  • Dormer as a kit build yourself
  • Insert finished dormer in the roof

Even with a finished dormer the installation is still very difficult

If you prefer standard dimensions or no fancy dormer construction, a dormer kit of a prefabricated dormer is to be preferred in any case. Also, the installation is then not quite as difficult, since there are numerous information on how to avoid errors in the construction instructions in the construction manual.

However, it must also be mentioned that the dormer itself build even with a Fertigkonstrukt is very difficult. In order to use a dormer, you must partially remove the roof structure. You may need to redirect purlins and reinforce them, but also strengthen the rafters with a frame around the dormer.

Without a structural engineer and construction office, nothing works

This in turn means that the purlins and the roof truss must be supported accordingly in the partial expansion. These are the reasons why you must also consult a structural engineer or architect. On the one hand he does the static calculations, on the other hand he also takes the plan off. This is important because a dormer is subject to approval. The architect also helps in the determination of optimal dimensioning.

Build step by step instructions for the dormer yourself

  • Material for the dormer basic construction
  • Material for the roof truss bypass
  • Dormer front with associated window
  • different insulation material
  • possibly material for the eaves
  • sealing material
  • Interior lining material (OBD or plasterboard, for example)
  • support posts
  • possibly plaster
  • possibly external insulation and cladding (such as slate tiles)
  • Fixing material (screws, nails, glue)
  • vapor barrier
  • suitable tool for removing the interior trim
  • Carpentry tool for partial removal of the roof truss
  • spirit level
  • Chalk line

1. Preparatory work

First, you have to remove the interior trim to the roof truss. This also applies to the insulation in the area of ​​the future dormer. The lower dormer front is now erected up to the roof height.

2. Remove roof truss

The roof truss is supported at the intended positions and partially removed. Draw the rafters to your measurements. If parts of the purlins have to be removed, it is highly recommended to work with a specialist company. Basically, the "diverting" and reinforcing the purlins but how to reinforce the rafters around the recess for the dormer works. It is important to explicitly support the roof truss.

3. Build the dorm yourself

Front substructure and dormer front (frame)

The removed rafters are now stabilized around the resulting hole with material of suitable strength. The measures of reinforcement come from the blueprints. The dormer front then build further and set the dormer frame.

The dormer cheeks

Do you want to build your dormer with stone cheeks yourself, the side walls are now masonry and plastered accordingly. If you use a metal or wooden construction, these (cheeks) are now inserted and mounted with OBD plates. All frame timbers should be sealed at the joint with a suitable adhesive.

Damming the dormer construction

With an external insulation you bring this on the Gaubenwangen. Then comes the disguise (for example, slate slabs). The interior lining (for example rock wool) comes on the OBD plates. In the same way proceed with the top of the dormer window.

The dormer top

Now put the window in the front, insulate the frame accordingly and mount the top. Now, if the entire dormer is provided with insulation, the vapor barrier is applied, followed by the battens or the framework, which later carries the interior lining - for example plasterboard.

4. Seal the dormer from the outside, insulate and cover it

Now the dormer is completely sealed from the outside and covered. The insulation is next to the support of the roof truss the area where most mistakes are made. If the roof dormer, which has been installed in-house, is now finished except for the interior fittings, an airtightness test is carried out.

5. The interior work

Finally, you can now proceed with the interior work. You may also want to put on radiators or make electrical installations. Accordingly, you proceed step by step in the interior design. The dorm itself is ready.

Tips & Tricks

A structural engineer or architect is essential, because he also has to sign the plans that have to be submitted to the building authority. When building a dormer, strictly adhere to the blueprint.

Only build a dormer if you are really sure you have mastered the work. Mistakes can be very costly. Either because everything has to be dismantled or a lot of heat is released from the dormer outside. Other common design flaws mean that water can not drain on the outside or snow catches unfavorably.

From the ridge, you should definitely keep two rows of roof tiles above the dormer window.

Of course you will find in the house journal also numerous guides and guides on different topics in interior design - for example, for [dressing with plasterboard] or for [laying tiles].

Video Board: Roofer / Dormer with slate