Correctly insulate a sheet metal roof afterwards

An old sheet metal roof can also be retrospectively insulated against noise and for heat retention. The same physical properties must be taken into account that are also important when insulating a new roof. Really effective constructions require a relatively large amount of space, so that lifting the roof is sometimes inevitable.

What is the goal of the insulation?

If a sheet metal roof is to be insulated afterwards, the first question that arises is which objective the insulation should fulfill. The following common options are possible:

  • The sheet metal roof should receive proper and contemporary thermal insulation in accordance with the Energy Saving Ordinance (EnEV)
  • The tin roof should only hold a little heat better, as is the case in temporarily used and unheated rooms such as garden houses and workshops
  • The tin roof rattles and / or is noisy when it rains and should get soundproofing afterwards

Insulation required in the substructure

In almost every case, the sheet metal should remain the top layer of the roof. Therefore, all insulation systems applied from above, which are entirely possible, are omitted.

Subsequent thermal insulation therefore almost always affects the substructure of the sheet metal roof. Some sound insulation is an exception, although it is more like a repair.

The substructure must remain dry

Most importantly, avoiding a condensation problem that arises. This can be realized construction technology almost only by ventilated metal roofs.

Simplified, an intermediate savings insulation can not be easily created by the "plug " of the cavities after applying a fairing inside. The sheet would seal the insulating material and make diffusion impossible. When condensation occurs, it waits the insulation and most materials lose their efficiency, apart from possible rot and mold.

A gap for venting between introduced new insulation layer and sheet metal roof is indispensable. Ideally, two interstices or air ducts are built up, which are separated with a vapor barrier.

Special case sound insulation

Before a complex acoustic insulation measure is planned to reduce noise, the thorough control of the existing roof construction is useful.

All fastenings and connections should be checked for strength and tightened if necessary. To prevent sound bridges, sleeves made of rubber or plastic can be retrofitted to the fastenings.

Tips & Tricks Avoid temporary solutions that are likely to lead to the formation of condensation. The subsequent correction or repair will certainly be more expensive than a higher investment in advance for subsequent insulation.