ᐅ Incorrect Installation of Interior Roof Insulation Caused Significant Damage

Hello!

I need to tap into the collective knowledge here.

In 2017, we bought a house built in 1921. The roof is from 1993 and has a vapor-tight (!) underlay membrane, which was common at the time. In 2017, we converted the attic and had it insulated by a drywall contractor. For that, they added battens, pressed the insulation wool tightly against the underlay membrane, then added insulation beneath the rafters, followed by a vapor retarder foil, and then the drywall.

So far, so good. However, during Christmas 2023, we had a storm/rain damage because the connection between the chimney and the roof became leaking. The roofer lifted some tiles there and found water everywhere. On the entire roof, there is condensation between the insulation and the underlay membrane. He checked under the tiles from outside on all sides of the roof. Afterwards, we opened part of it from the inside—everything was wet (well beyond the chimney area—the insulation around the chimney was drenched from the rainwater leak, while the rest of the roof only has condensation between insulation and underlay membrane).

The roofer told us the interior insulation was done incorrectly. They should never have pressed the insulation directly against the airtight underlay membrane but created some ventilation space of a few centimeters. Now all the damp insulation wool must be removed, which is a huge effort and a major cost. The chimney leak was sealed, and it will require proper repairs in spring, but that is clearly separate from the condensation damage. The condensation problem probably would have gone unnoticed until the drywall started to rot.

What do you think? Does anyone have experience with this and any tips, ideas, or suggestions? Is it possible to hold the drywall contractor accountable? There is already light black mold on the beams, and the entire insulation plus drywall must be removed, disposed of, and replaced. I estimate the cost to be roughly 10,000–15,000 EUR. Only the thinner insulation mats beneath the rafters are dry and might be reusable. We don’t expect any goodwill from the drywall contractor. We want to take legal action if possible; after all, we hired a professional company back then to prevent exactly this kind of issue. We paid a significant amount, and it was only six years ago.

Unless you have agreed on a separate warranty, the period ends after 4 or 5 years depending on the type of contract, and you basically cannot take any action afterwards. Unless you can prove deliberately concealed defects – which seems rather unlikely in this case. You can check what was offered or invoiced to you at that time.

The issue with the roof and insulation has actually been ongoing for quite some time. We first suspected a problem in 2019 and had drywall installers and roofers come to check. In the end, they agreed it was only a limited damage because two staple holes were not sealed. We let it dry out and then sealed it again. Despite repeatedly calling to follow up, the roofer never showed up for the promised roof inspection, so we assumed it was fine and dry and left it at that. At that time, it had only been 2 years since the installation – does that make any difference?

The problem is: if you rely on professionals, you’re often left disappointed. But as laypeople, how are we supposed to know about these things? You really have no chance of noticing something like this – and when you do, it’s already too late.

This is really tricky. I would probably start by hiring an expert. If this expert confirms that the drywall contractor carried out the work in violation of regulations (standards, technical rules, etc.) that were already in place at the time, this could be considered fraudulent or intentional wrongdoing, and with some luck, you might even have legal grounds for a claim. If the expert is not very optimistic, your only option may be to negotiate with the drywall contractor and try to persuade them to contribute to the repair costs in order to protect their reputation. The problem with drywall work is that it is not a trade requiring a master craftsman certificate to operate a business. In other words, there are many unqualified people working in this trade.

The contracted drywall installer also works partially on public projects. So we assumed he was reputable.

After reading a bit about fraudulently concealed defects, I will first seek an initial consultation with a specialized lawyer. Since we have a vapor-tight mesh foil, ventilation was actually necessary; at least, that is what is stated everywhere. Only with a vapor-permeable underlay membrane could the ventilation have been omitted. In this respect, the damage was predictable.

Depending on what the lawyer says, we will talk to the drywall installer. Of course, he will not admit, “Sure, it was my fault, I’ll fix it properly.” Then we will have to see what to do next. For now, we are waiting to hear what the lawyer advises.

But now you have done some research and realized that it was not executed correctly. Why didn’t you do this before or during the work? It wasn’t that much effort to just look it up online, right?

Of course, professionals should do their work properly. But you’re not 20 anymore and already have quite a bit of life experience, don’t you?

At least during the construction phase, I tried to understand each trade roughly and did a plausibility check for myself to see if it could be correct as executed. Additionally, the site supervisor for the shell construction was related to us and was very meticulous in ensuring many trades were done correctly. Still, I definitely don’t want to say that everything went perfectly with us.

Why don’t “laypeople” hire a paid expert for supervision who speaks on behalf of the client? (I include myself here despite my background as a construction drafter—civil and road construction—and partly studying civil engineering.) Without my brother (a civil engineer) and the site supervisor, and consultations with our architect (partly phase 5 of the service phases), we certainly would have hired someone like that as well.