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Dormer Window Costs

The average cost to add a dormer window to your home is $12,000 based on figures taken from all across the USA. The lowest price is $2,500 and the highest $20,000. Per square foot, the average cost to add a dormer window is $115 with many variables based on the style of dormer, the glazing, your roof type and where you intend to put the window.

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Dormer window costs

Type of Dormer Cost per square foot
Flat dormer $80 - $125
Shed dormer $75 - $120
Nantucket dormer $95 - $140
Gable dormer $110 - $150
Hip dormer $115 - $135

Dormer window costs by type/design

Type Cost
Bungalow $110 - $150 per square foot
Cape Cod $110 - $150 per square foot
Attic $75 - $120 per square foot
Bathroom $24,000 average cost
Dormer window $3,000 - $8,500

Checkout this short video on Dormer Windows:

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What are dormer windows?

The word ‘dormer’ comes from the French, ‘dormir’ meaning to sleep and this is the big clue about this style of window. Dormer windows are vertical units positioned in part within the frame of the roof. They are popular for loft conversions as they offer both light and headroom, a considerable improvement over the standard Velux. Not just for attic conversions, they are also a regular choice for more traditional houses if the bedrooms are cramped and gloomy.

What factors affect the cost of dormer windows?

Some of these factors will affect the price of any window whereas others on this list specifically relate to the dormer window style.

  • The number of dormers
  • The size of the dormers
  • The type of dormer design
  • The choice of window style for the dormer
  • The material for the frame
  • The type of glazing used
  • The roofing material – dormers windows will have their own roof
  • How much work will be required to alter the roofline of the house
  • The type of roof
  • Reinforcement requirements
  • Where you plan to install the dormer
  • Building permits which are typically anything from $390 to $1,930.
  • Depending on the type of dormer or dormers you plan to add, you may need planning permission
  • Access to the site
  • Whether you want dormer cladding, this costs from $2 to $15 per square foot
  • The size of installation company
  • Interior finishing and decoration
  • Your zip code

Professional fees and third-party costs

Most people who install dormer windows in their home will need an architect and an engineer both of whom will attract sizable professional fees. Don’t forget third party costs like scaffolding hire; these may not appear on your window estimate and will be billed separately.

Shed dormer costs versus gable dormers

Gable dormers are also called doghouse dormers because they resemble a dog kennel. They are usually found on roofs with a steep pitch. Gable dormers are attractive and cost-effective.

Shed dormers or as they are sometimes called, full dormers, are a more expensive investment compared to gable dormers, but they offer an increase in square footage plus add headroom.

Minimizing the cost of dormer windows

You can only cut costs so far with dormer windows because of all the essential building work which surrounds them. Cheaper frames and glazing can reduce costs to a degree, or you could just less to your attic conversion.

Do I need a window contractor or a builder for dormer windows?

Unless you already have dormer windows installed and just want an upgrade or new glazing, a building firm is probably the best way to go when it comes to installing dormer windows.

Cutting into your roofline is a pretty expert job which will require the input of engineers and architects plus a construction firm that really knows what they are doing. This doesn’t mean you can’t use the input of a good installer when it comes to choosing the frames, glazing and window features but the actual work is best carried out by a qualified construction specialist.

How to find the right window contractor

Most window contractors who offer dormers as part of their range, will work with construction firms or you can choose your own builder to fit the window of your choice.

Each window installer will have their own arrangements for dormers, either leaving it up to you to find a builder or some of the bigger companies will have their own teams of installation specialists.

Dormer windows can look ridiculous on some properties, they just don’t work regardless of what they might add to the interior. Therefore it is important to find a good designer or installer who will recommend what’s right for your home, not just the most expensive product.

How long does it take to build a dormer window?

The answer to this depends upon your project. A sole dormer window can be done in two or three weeks but an attic conversion with several dormers can take up to six months.

Adding dormer windows to your home is a serious structural job; this is something many householders don’t realize and significantly underestimate the amount of work, the cost and the time it will take.

Dormers will take sections out of your roof and so there is quite a lot of construction work to adapt the roof and make sure the windows fit tightly and are waterproof and weatherproof. The roof and the rest of the house must be able to bear the extra weight so sometimes reinforcement is required.

What are the benefits of dormer windows?

Dormer windows are the way to go if you want to increase space and light in compact or tight areas upstairs in your home. Small bedrooms on the first-floor benefit hugely from a dormer window and they bring an attic conversion to life, maximizing all the potential of this unused roof space.

Dormer windows can feature a range of different window designs including full height picture windows and even the addition of a balcony. None of this is possible with a regular Velux.

Well chosen and placed dormer windows can add architectural interest and detail to the exterior of what may otherwise be quite a bland property or a house that is just one of many identical designs in a particular street. Dormers are a very versatile window in terms of design, there are plenty of different styles so there is bound to be one to suit the roofline of your house.

Rooftop dormers can provide better ventilation for the upper floor of a house even if you don’t have an attic conversion. They can also provide an emergency escape route through the roof in the event of a fire.

What are the disadvantages of dormer windows?

The biggest disadvantage of dormer windows is the extent and cost of the work that is required to install them. Skimp on this and you will end up with an inferior product that doesn’t look good and lets in water, plus a poor installation could end up seriously damaging your roof.

Dormer windows for an attic conversion are a major structural change to the house and are more complicated than many homeowners realize.

What can dormer windows add to the interior?

Apart from natural light and headroom, dormer windows can add a real feature to the interior. Some people create a window seat, perfect if you have far reaching rural views or an impressive city skyline.

Dormer windows can add a lovely play area in a kids’ attic bedroom or a dedicated office space in a rooftop studio or home working space. If you have converted the attic to add an open plan master bedroom and ensuite, then a dormer window makes a perfect reading or dressing area, with plenty of natural light. A dormer window offers a separate study area for a teen bedroom.

Funding the cost of dormer windows

Even if you are not converting the attic – maybe it’s already been done – dormer windows still require a sizeable budget. The professional fees and labor costs are one thing but the dormer units themselves are also expensive.

For large capital costs like this, some homeowners look to their mortgage company for a home improvement loan if they don’t have adequate savings. If you have equity in the property and can afford the higher monthly repayments, then it is worth the investment in terms of what dormer windows can add to your property value and the improvement in your living accommodation.

Another option is to remortgage to another lender. This is a good opportunity to release capital and maybe find a lower interest rate.

Schemes like this are generally not funded by government grants although you may find you are eligible for a small contribution in terms of the type of window you choose to fit to the dormer. Energy efficient glazing which controls the loss of heat from the property can attract a grant. These grants are available at federal, state and local level. Your installer or builder should be familiar with what is currently on offer.

 Frequently Asked Questions

Can I install a dormer window myself?

Whilst most householders can undertake a bit of window maintenance and repair themselves, refitting windows is usually a job best left to the professionals – with dormer windows this really is the case, especially as you will be working at height on the roof and so there are numerous safety considerations. A professional builder will sort out local permits, follow the necessary building codes and deal with any structural concerns involved in opening up your roof frame and adding extra weight to it with new dormer windows.

When is it beneficial to add a dormer?

Dormers are ideal when you want to add light and in an attic conversion, they can also add headroom saving the huge cost of a roof lift.

Do dormer windows increase the value of your home?

Dormer windows have an ROI of around 40%, that means a Return on Investment. They will increase kerb appeal and if you add them to an attic conversion, can really transform the space with added headroom and light. 40% is not such a good ROI as other types of window replacement which can reach nearly double that but if you are converting an attic space for extra accommodation, then your window options are more limited.

What is a Nantucket dormer?

A Nantucket dormer is a mix of a shed and gable dormer style window. Two gable dormers are installed and then connected with a shed dormer to form a Nantucket dormer.

What are faux dormers?

Faux or fake dormers are just that, purely cosmetic additions to your roof which don’t actually have a working window but are simply designed to look good and give the appearance of a real dormer window. They are cheaper than the real deal but clearly, don’t offer the benefits or advantages of a proper dormer window like square footage or ROI. Faux dormers are fitted to make the roofline look more interesting and to give the house a grander appearance.

Is a dormer window a better option than a Velux?

Dormers do add more light and headroom than a Velux but whether one is better than the other depends upon personal choice, the options available for the roof and the homeowner’s budget. Some people start with Velux when they are converting an attic and then upgrade to dormers later on. This can be prompted by a change of house owner, a repurposing of the rooftop accommodation or it's just a good way to spread the cost.

What type of house is a dormer window suitable for?

Because of the range of dormer window designs, they are a potentially suitable option for lots of different types of property.