Points of attention when installing a dormer window

Two other articles are linked to this item; in some cases, a dormer can also refer to a roof extension or ridge increase.

• Lead flashing dormer (bottom of frame)
• Lead flashing dormer sides (side cheeks) or concealed gutter
• Buying a house with a dormer window? Check the permit

Insulated glazing . The dormer's insulated glazing can be inspected for defects. The glazing may be leaking, or other defects may be present. If defects are found, replacement of the insulated glazing is recommended in the future.

Older insulating glazing (also commonly called double glazing). This is therefore not high-efficiency, HR+ or HR++. The risk with this older double glazing is the bonded strip or edge seal that is installed around the glass. This bonding will eventually come loose spontaneously, and/or other defects may develop, causing the glazing to leak and potentially cause condensation on the inside.

• Condensation isn't always immediately noticeable, and neither is leaking double glazing! This depends on factors such as weather conditions.
• With such older double glazing, you can count on it having to be replaced in the short or long term!

Single glazing or secondary glazing. If present, there are still advantages to be gained in terms of the home's energy efficiency and living comfort. This means there are opportunities for improvement in terms of comfort and energy savings. Insulated glass reduces condensation and keeps the house warmer. Living comfort will be significantly improved with high-efficiency glazing.

• Secondary glazing does have an insulating effect, compared to single glazing this has an effect of at least 50%.
• Secondary glazing cannot be compared with insulating glazing (for example hr++).
• Externally mounted secondary glazing requires additional maintenance, such as cleaning.
• Secondary glazing, if mounted on the outside, also poses a risk of wood rot at the fixings.
• Secondary glazing is certainly no longer recommended in a new or changed situation.

If the dormer's side walls are painted , there's a higher risk of wood rot, especially along the sawn edge (bottom). This end wall is usually unpainted, but it's the most vulnerable because rainwater adheres to it as droplets and is drawn upward by capillary action.

The dormer side panels can be made of low-maintenance materials . It is recommended to clean the materials regularly and check the fastening.

The dormer side panels can be clad with zinc plating . This is an excellent, low-maintenance material for the sides of a dormer. Regular cleaning of the materials and checking any soldering is recommended. Because dormer side panels generally don't experience much wear and tear, these materials can have a lifespan of 40 years.

The dormer's side walls can be covered with slate, tile, or other stone-like cladding . This is an excellent and low-maintenance way to add a touch of color to the sides of a dormer.

The dormer's side walls may be covered with bituminous shingles , a roof covering consisting of individual overlapping elements made of bitumen-impregnated or soaked rough felt or a fiberglass mat. Bituminous shingles are covered with bitumen on both sides and usually have a protective layer of mineral granules on the top.

The side walls of the dormer window can be part of a prefabricated (aluminium or plastic) dormer window, and are one unit with the roof and the overhang.

Whether the dormer's side walls are clad with coated steel sheeting . The materials behind these finishes cannot be assessed.

• The advantage of this covering is that painting is unnecessary.
• It is usually not easy to determine from the visible side whether the cladding has been applied in a ventilating manner.

Whether the dormer's side walls are covered with cement-bonded wood-fiber board is an excellent, low-maintenance material for the sides of a dormer. Regular cleaning is recommended.

• Cement-bonded wood fibreboard is a high-quality board material with exceptional properties.
• Cement-bonded wood fibreboard is obtained by pressing wood fibres, Portland cement and water glass.

Whether the dormer's side walls are made of an unknown hard material . If a material cannot be immediately identified, there is always a risk of suspected asbestos materials.

Check the sidewalls for wood rot. If wood rot is present, it will need to be professionally repaired. Any previously repaired wood rot should also be checked and professionally repaired. Wood rot repair is usually possible, but it is best done by a professional with the right materials and tools.

• The disadvantage of wood rot repair is that the painting work must also be carried out immediately afterwards.
• If during repair it appears that more wood rot is present, it may still be decided to replace a side wall.
• Replacing a side wall with a solid core (low-maintenance) material can always be considered.

If the original dormer side panels are clad with a solid core or synthetic material , the materials behind these finishes cannot be assessed. The fact is, a dormer side panel is usually clad with such a material for a reason. It's possible that the underlying woodwork is no longer in good condition. Furthermore, we often see that this material is not ventilated. This prevents ventilation between the different materials, and there is a high risk of condensation, resulting in damage to/wood rot of the underlying woodwork.

In that case, we recommend removing the material covering the dormer's side wall and reapplying it professionally (on rubber) and ventilated, and/or restoring or restoring the dormer's sides to their original appearance. Removing the solid wood or plastic material may reveal defects in the underlying woodwork.

If repair or restoration of the side walls is no longer possible: It is best to replace the entire finish of the side walls. We recommend using a low-maintenance solid core material for this. Alternatively, the lead strips between the side walls and the roof surfaces can be replaced at the same time.