Wood pest expert report old building house borer powderpost beetle

We are about to purchase a house. The house was built around the turn of the century (1885-1915) and an expert has identified pest infestation in the attic and on the cellar ceiling. Attic: softwood, cellar ceiling: oak beams.

Attic: moderate infestation of some rafters and purlins by the house longhorn beetle.
Cellar ceiling: sapwood area infested by the common furniture beetle. Especially beam ends are affected.
The expert report cannot completely rule out that this is a current infestation, even though no traces of predatory insects that hunt the larvae were found, nor was any boring dust detected. The expert report recommends a sledgehammer, axe, and chisel for the removal of the damaged wood. A severe destruction of the beam ends is described; all beams should be inspected. Reinforcement of the beams is advised.

In contrast, the offer from a local pest control company reads as follows:
"Fresh feeding tunnels and exit holes were found in the attic and in the ceiling beams. To prevent the infestation from spreading to the healthy wood, urgent remediation according to DIN 68800 Part 4 is recommended.”
Method: wood pressure injections with Adolit Anti Insect 0.02% Permethrin.
Duration: 4 days. Estimated cost: approximately 5,000 euros.

Does anyone have experience with this type of infestation? Can anyone offer advice on whether this treatment is “worth it”? We have to decide in the next few days whether we want to buy the house and would greatly appreciate help. If you have questions, I am happy to quote more from the expert report and the offer. Thank you!

Here, I would rather listen to the expert report and have the beams completely checked. Consult a carpenter who will inspect the beams one by one.

Tips from a distance are, in my opinion, unreliable, but it is true that pest control does not improve already damaged beams. A pest controller is certainly capable of using the right agents, but I doubt their ability to assess which woods are "healthy." Personally, I would not want to invest 5,000 euros with an uncertain outcome.

Sure, such old houses have their charm, but also their pitfalls.

The decisive factor is the statement of a neutral expert for wood and building protection, who can tender the measures as a concept but does not provide these construction services himself. The so-called "free" expert reports/recommendations etc. from companies that also happen to have the right remedy on hand are, of course, not independent. In the case of the described infestation, it may be statically necessary and economically more sensible to replace the affected component rather than laboriously removing the infestation, reinforcing the cross-section, or restoring it. I do not support the recommended chemical pest control measures because the infestation cannot be precisely located and therefore cannot be precisely combated. Here, removing the infested areas is safer. Nevertheless, the house longhorn beetle can still hatch again after 7-10 years in cases of acute and undetected infestation, and the whole issue goes into a second round.

The cellar ceiling must be completely renewed if necessary. It is a "wear part" and is usually—also in oak—more or less eaten away by anobiids or heavily soiled in the area of the masonry supports/beam heads. If the house is a half-timbered house, the FW construction should also be examined for infestation and soiling.

With the briefly described damage pattern, the overall condition of the object should, of course, be carefully examined before purchase and the actual renovation effort quantified. If extensive repair measures should be unavoidable, the purchase is probably not really worthwhile.

Hello and thank you very much for the detailed and helpful answers. In one of the basement rooms, a steel beam has already been installed below the living room area, the so-called "Angstbalken" as the real estate agent and owner called it. The report states that the structural integrity is not at risk. Now we are naturally wondering why components would need to be replaced if existing constructions could be reinforced with steel beams, etc. The house is partially basemented, so the floor in the other area is not supported on a basement.

Removing the described areas is more sensible, you say. In another forum, the hot air method is also mentioned, which can be very effective. Do you have an opinion on that?

Hello,

Removing the described parts makes more sense, you say.

We are not so formal here; our "language" is the informal "you"

Rhenish greetings

The hot air method is very costly and is used for valuable historical and listed buildings. For private budgets, it is usually not an option. If the ceiling structure is already supported over the basement, it is no longer load-bearing and must, as already described, mostly be completely renewed with other materials (steel beams or Steuerberater ceiling or swallowtail steel trapezoidal profile with topping/concrete screed, etc.). New wooden beam ceilings in this installation situation are really not recommended. The floors in the non-basement area will be rotten. In energy renovation measures, a completely new, insulated floor construction against the ground must be planned and installed here. All of this must be considered before purchase. Since I have inspected a large number of such buildings, I know the damage patterns and the associated renovation effort. I advise caution and a very realistic assessment of the property.