Roof renovation with aluminum, recommended?

Our energy consultant recommended an aluminum roofing after inspecting our roof, as we want to redo the covering anyway.

So a structure on the original rafters including insulation.

Advantages of aluminum coverings:

- very low material costs compared to conventional coverings
- available in many colors and variants
- only 10% of the weight of a covering with slate, concrete shingles, etc. (good for old rafters)
- there are apparently prefabricated elements with insulation
- very long durability up to over 100 years with correct installation and maintenance

Disadvantages:

- high thermal expansion that must be considered during installation (special expansion possibilities and fastenings)
- clicking noises can occur due to thermal expansion
- the thin aluminum sheets are easily deformable, e.g. in hailstorms. Not every insurance covers such damages.
- the insulation should also act as soundproofing, as raindrops might otherwise be audible inside the house
- corrosion can occur if the aluminum elements are fastened with "wrong" metals or otherwise come into contact with them.

Unfortunately, I have not yet read much online about old buildings with aluminum roofs, so I wanted to ask here if anyone has experience with that? Basically, we tend to go for an aluminum covering when the renovation starts at the end of the year.

What do you think?

I only know the material from shipbuilding, where it is commonly used. It forms its own protective layer, so it does not need to be painted. Aluminum must never come into contact with steel, especially not stainless steel. Aluminum to copper is particularly bad. In contact with water, aluminum crumbles into a kind of powder. You have to insulate the contact surfaces with plastic bushings, for example. Then it is fine. Aluminum is light. Whether it is really cheaper than a pan roof, I dare to doubt. Karsten

Instead of Monday, the roofer is coming to us on Thursday now. He is supposed to tell me something about the [Aludach] and the prices.

I will report.

I would say an energy consultant should stick to their area of expertise. A roof covering with large-format sandwich panels looks visually impossible for a residential building and is also difficult to impossible to properly install on an old crooked roof structure. A covering with small-format aluminum shingles or standing seam aluminum sheets is by far more expensive than a tile covering.

What does the old roof structure look like and what is to be achieved (Energy Saving Ordinance renovation or KFW)?

Best regards, Sven

So far, the energy consultant has only talked about KfW. Today he was on site with the roofer who will be doing the work later, and we discussed the two roofs. I have to correct the measurements: the roof surfaces are about 120 sqm each, so roughly 240 sqm in total.

I also looked at an old building near us, which was recently renovated with dark aluminum cladding in a shingle look. It also looks very good up close. Only the dormers and chimney coverings are clad with slate, which harmonizes visually. We are now being offered the same method, including the demolition of the last piece of chimney in the attic and on the roof. This will be replaced by 2 insulated stainless steel pipes, which are used for external chimneys.

I am very curious about the complete offer. It includes:

- Scaffolding costs
- Removing the covering from 2 roofs down to the beams and rafters, which can remain. One roof has slate covering, the other has bitumen coating
- One roof of 120 sqm with KfW-compliant external insulation and aluminum
- One roof of 120 sqm with only slight insulation (extension, top floor is insulated) and the same aluminum
- New gutters
- Removing one dormer
- 2 larger Velux windows KfW-compliant
- Cladding an existing dormer with slate

Sooner or later, both frameworks will be treated against possible woodworm infestation (by the pest controller).