Underground buildings and homes

Building underground homes or extensions has never been more popular. Modern damp-proof membranes and insulators have eradicated the problems of cold, damp buildings but the issue of natural light can still be the deciding factor in the success or otherwise of a project. In order for an underground house to feel enough of a home rather than a bunker, the levels of natural light need to match, or even exceed those expected in a ‘traditional’ house.

There is absolutely no reason why an underground house shouldn’t be as bright, or even brighter, than a conventional surface built house. The inclusion of sufficient Solarspot® Tubular Daylight Systems (TDS) can more than compensate for the lack of conventional windows. In fact, it’s possible to create rooms that exceed the brightness levels enjoyed by window-lit houses.

More light than a window

Firstly, when using a series of TDSs to light a space, you can be sure that all of the light collectors are facing the source of our light, the sun and sky. Unlike conventional windows that face out level with the ground, a Solarspot dome can be relied upon to delver the maximum amount of available light without concern of limitation like aspect (being north-facing) or shading from other buildings.

In addition, due to its light-catching technology, a massive amount of light can be gathered through a comparatively small aperture. This means that an average room could be well-lit with just two D-38 (375mm diameter) Solarspot systems – delivering much, much more light than could be achieved with a window of the same area. A bathroom or en suite would only require a D-25 (250mm) TDS.

Thermally efficient

Because of its triple-glazed design, a Solarspot TDS is also incredibly thermal efficient, guaranteeing maximum light with minimum heat loss – or heat-gain during the summer. They should also be completely maintenance free.


Correct installation is vital, particularly if a green or living roof is to be used. It is not sufficient to install a flashing to the house roof-raft and then to bury the pipe in the soil and not expect future problems. A certain underground house in Cumbria featured on Grand Designs is a classic example – fails in two very important areas.

Firstly, light tubes are designed to fit through roof voids, not soil. The addition of a simple, insulated up-stand, sealed to the roof-raft and topped with a suitable flashing will guarantee a maintenance and condensation free system that should continue to deliver an abundance of light for years to come.

The second issue is specifying the correct number of units. The simple rule is that you can’t make the house too bright. To install one 300mm light pipe into an average kitchen and expect it to do the job of a large window is naïve to say the least. If anything, over-lighting the space will compensate for any psychological effects or expectations of being underground. The worst possible effect of over-lighting will be to create a well lit space to rival that of a conservatory or garden room – without the heat or glare.

If you’re planning an underground house and need some advice or more information, contact us today on +39 0332 700137 or email on This email address is being protected from spambots. You need JavaScript enabled to view it.