ᐅ New Construction: Is the Attic Suitable for Conversion or Not?

Hi,

we are planning to build a single-family house with two full floors plus a pitched roof (as a third floor) without a basement (due to groundwater).
So far, we have planned the attic as an unheated roof space without knee walls, with a roof pitch of 35 degrees (roof pitches must be at least 35 degrees according to the development plan, and knee walls are allowed up to 1.20 meters (4 feet)).

The upper floor ceiling will be made of wood – insulation will be installed there. The attic will be designed to withstand loads up to 2 kN/sqm (42 psf), so it can be used well for storage of non-sensitive items.

We are covering about 100 sqm (1,076 sq ft) of ground area and will have approximately 165 sqm (1,776 sq ft) of living space spread over the two floors. That is actually sufficient for our needs.

However, we are now reconsidering whether it might be better to design the attic so that it can be used as living space:

* Upper floor ceiling made of concrete
* Underfloor heating installed / electrical provisions made
* Insulation in the pitched roof
* Knee walls installed
* Roof pitch increased from 35 to 38 degrees

We probably would not have this option later on.

We do not urgently need the space right now, but we could imagine setting up a “relaxation/leisure area” there. In addition, this would create space where our heating system could be relocated, and it would provide genuine storage (storing things in an unheated attic is quite difficult).

Thanks for your thoughts/opinions on this question.

I would definitely design it to be expandable – in my opinion, it always makes sense to keep options open rather than to limit them.

What is the minimum that needs to be done now to make it suitable for future expansion?

For example, can the seemingly more affordable wooden ceiling remain? Should I possibly only invest in the additional costs for the knee wall and roof pitch now? The wooden beam ceiling can later be opened more flexibly to connect the staircase... For now, we would access the attic with a pull-down ladder.

You should discuss this with your architect. I would recommend installing the staircase now—preferably a simple wooden stair—to avoid having to use ladders, as the attic is otherwise very difficult to use as a storage space.

You might also consider running plumbing pipes up there in case you want to install a bathroom later.

It is no problem to make a wooden ceiling accessible from above. Just lay boards on it, and it works. A staircase up and a small hallway upstairs with a wall and door is really quick to do. Electricity also up there. Don’t forget a Velux window. Heating and water as well as wastewater, if not too expensive, can also be installed upstairs. Radiators can be used upstairs. Karsten

Thank you for the responses. After further consideration, we want to use the attic as fully functional storage space—not as living space. This means the attic needs to be insulated so that items stored there will not be exposed to moisture or extreme heat/cold. At most, we want to optionally use the space as a "hobby room" for activities like crafting or tinkering. Therefore, we want to prepare the option to connect a radiator for heating.

At the same time, the roof structure should remain cost-effective → prefabricated timber trusses as studio/storage trusses.

Now to my questions for you:

Cold/Warm Roof

The insulation relevant for the residential building according to the energy-saving regulations is still installed in the upper ceiling of the top floor. How should the insulation of the studio truss roof be designed? Should it be constructed as a warm roof in this case?

Ventilation Concept

I plan to install forced ventilation (RegelAir or similar) at the two gable windows to ensure some air exchange in case the attic is not accessed for a longer period.

Roof Access

The trusses will be spaced at about 1 meter (3.3 feet) intervals. What is the maximum width allowed for the pull-down ladder? Is an 80cm (31.5 inches) wide ladder sufficient for comfortable access to the attic, or would you recommend a wider hatch? (However, a wider opening might cause structural challenges.)

DIY Work

Is it advisable to carry out the attic finishing work myself—such as installing tongue-and-groove boards as flooring, insulating the roof, and fitting vapor barriers/drywall—to save some money?

Thanks & best regards