ᐅ Water Damage in Ceiling Construction of Timber Frame Buildings

For a prefabricated house built in 1996 using timber frame construction (not a branded house), the ceiling structure consists of chipboard on the top and bottom of the ceiling joists, yellow insulation wool inside, with battens and drywall on top. There is no vapor barrier installed.

After a major water damage, fortunately the water drained straight into the basement, and the ceiling was almost dry by the time the drying company arrived. They cut three holes into the drywall and also into the chipboard using a hole saw.

Does the small hole for the injection opening in the chipboard need to be sealed (if yes, why), or can it be left open? It would no longer be visible once the drywall is closed.

Currently, a drain pipe resting on the ceiling is slightly leaking. The ceiling has been partly cut away because the pipe runs downward through the ceiling (several angled fittings, then the main drain). I suspect one of these angled fittings is leaking, dripping directly into the ceiling without any visible damage above. Would the leak detection service be able to inspect the ceiling from below through the hole with a camera or probe until they reach the pipes? Also, making a 1.2 cm (0.5 inch) hole in the insulation wool should be unproblematic, right? The bathroom above is fully tiled, so causing damage there would be more severe.

The later repair of the pipes located in the knee wall might be possible from the roof? The roofer recently lifted two roof tiles and saw the pipes in the knee wall area. Could the underlayment membrane be cut open and resealed afterwards, and could a piece of batten be cut out and refitted after the repair, or would this be not allowed? That way, a smaller person could simply climb from the outside into the knee wall and replace the angled fittings. In my layman’s opinion, this would be better than opening the tiled wall from the bathroom.

Hi,

Fleissiger schrieb:
Does the small hole for the injection opening in the particleboard have to be sealed (if yes, why?) or can it be left open? It wouldn’t be visible anymore once covered by the drywall.

The hole must be sealed. Even if it is hidden behind the drywall, it remains an open connection between two protected layers within the ceiling construction. Air exchange through an unsealed particleboard can promote condensation, odors, and ultimately mold growth. Especially when there is no vapor barrier, any additional leakage is highly undesirable. Visibility does not matter; the function of the layer is the crucial factor.

Fleissiger schrieb:
The leak detection service could simply look inside the ceiling from below through the hole with a camera or probe until they see the pipes. Making a 1.2cm (0.5 inch) hole in the insulation wool should also be unproblematic, right???

That makes technical sense if it’s clear beforehand that the insulation wool does not replace any load-bearing or airtight layer. A small hole for leak detection is acceptable as long as it is properly sealed again afterwards. When drilling and searching, don’t forget to restore the airtightness of the layers afterwards as well.

Fleissiger schrieb:
Could the underlay membrane be cut open and resealed, and a piece of the batten cut out and reattached after the repair, or is that not allowed?

Technically, that is possible; tradespeople work like this in similar cases. However, the underlay membrane is part of the weather protection and must be properly sealed again afterwards.

Good luck!

Thank you very much! Is there possibly an explanation for why the wood moisture level differs so much from that of the drywall? At first, I thought it was damp again, but I couldn't find any signs at all. The wood underneath is dry. And even days and weeks later, I keep measuring the same values at the exact same spots! Could it possibly be due to the joint compound, the liquid textured wallpaper, or the paint?