Planning a granny flat

Hello dear construction friends :)

Next year my wife and I are building our own home – or rather, having it built. It will be a simple house with a gable roof and brick cladding.

We have now come up with the idea of also building a granny flat. The catch is, we currently have no money to invest in building this apartment. So we thought of seeing it as a little hobby and just building the house ourselves, step by step, as soon as money is available again. To be clear, we have no experience with this topic, but we are at least somewhat skilled in craftsmanship, so we believe we can do the essential work ourselves. It’s fun and you grow with your tasks...

But what is it about exactly? It’s certain that the mentioned residential building will have a granny flat directly attached, but with a separate entrance. The granny flat will be very small, about 25 m² of living space and only one floor, because it is only intended for friends and holiday guests. Another reason for the size is that we don’t want to "build over" our beautiful property with an apartment for strangers. It is simply a hobby... Nevertheless, the little hut should of course have all essentials – bathroom, kitchen, double bed.... Since we are not applying for subsidies, we are not bound to energy standards, but of course it should be properly insulated ;) On top, it will probably have a flat or shed roof, we’ll see. Why plan it now if it will be built later? Quite simple, because we want to submit the building application for the granny flat together with our house to be on the safe side. Once we get approval, we will pour the foundation first and then proceed as described later.

We don’t know much more yet; I’m currently entering the planning phase. However, before I hire an architect, I want to get some advice here on how you would approach this.

My first very concrete question is about the facade. As mentioned, it should insulate well in the end but be as thin as possible – of course only as long as the costs remain reasonable. A thermal insulation composite system with polystyrene is categorically ruled out! Our house will be built with Poroton. But I can’t judge whether this is also suitable for such a granny flat and especially for an inexperienced bricklayer. So what are your suggestions for the facade? Would you connect the facades of the main house and the granny flat somehow, or leave a gap?

What other pitfalls come to mind that a layperson should be clearly aware of?

I don’t want to be too restrictive. Please just express whatever comes to mind. I think I will take away a lot of things to include in the planning!

Many thanks!

You want to add a granny flat as a second construction phase to a building, whose planning (including its heating system etc.) did not yet take this into account?

A granny flat for long-term rental must comply with the same Energy Saving Ordinance regulations as the main residential unit; it may be different for a holiday apartment, but holiday apartment rentals are not permitted everywhere.

For the inexperienced bricklayer, aerated concrete would still be almost the most recommendable, better a "prefabricated house" than a shell house variant, doing even the exterior wall interior paneling yourself. Much of the effort for a residential unit (gas, water, sanitary, and electrical) hardly decreases significantly with a smaller living area.

Overall, I consider the boundary between a hobby project and a crazy idea here to be fluid.

If a second residential unit or holiday apartment is allowed, then a mobile home is an option. I just googled out of interest: Daalmann mobile homes or Meiselbach mobile home... the foundation will still be added to the prices, as well as connection to sewage, electricity, and water. Sewage pipes must also be approved, for example.

Otherwise, I would say: where is the liquidity supposed to come from? Any remaining money will probably flow more into the still necessary outdoor facilities and special repayments. A guest can also be accommodated in a hotel or guest room in the house – both are much cheaper than a hobby construction that will never be finished.

No, it is not meant for long-term rental, as I said.

As for the size, it’s not about the effort, but rather that we don’t want to build it larger for space reasons. You could have spared yourself the flippant comment about the crazy idea after my introduction, though.

The money flows into our account every month ;) The outdoor facilities are taken care of, and we can still make special repayments, even more than before, once the granny flat is built. We are in no hurry. It’s perfectly clear that guests can also be accommodated elsewhere. But we are deliberately foregoing the cozy option – besides, a decent hotel room so close to the Baltic Sea is significantly too expensive...

However, you could have spared the flippant comment about the crazy idea in my introduction.

That may be, but I haven't just read the introduction ;-) and of all options, building an extension with 25 sqm of living space will by far be the most expensive if done as an extension. Your text just oozes naivety.

Much more sensible is to plan the 25 sqm of living space as part of the ground floor from the start, basically as a king size guest room with shower bathroom and stove connection, and then simply do everything yourself from the windowed and externally plastered shell. Without KfW special repayment, it doesn't matter when residential unit 2 is completed.

Integrated like this, the question of wall material doesn't arise. Both this and the question of building an extension with or without a seam read like pretty clear indications of a naive approach. In this respect, I even believe the schnapps would suffice for an entire bowling club (bowling is somewhat like boßeln for Rhinelanders).