Comparison between Predicted and Measured Moisture Content and Climate in 12 Monitored Timber Structures in Switzerland
Round 1
Reviewer 1 Report
The paper is generally very interesting and very much relevant for the timber building sector.
The manuscript is mainly well written, but 1.) English language requires editing by a native speaking person familiar with the subject, and 2.) fails completely to follow an established structure.
The latter is the major flaw of the paper: Introduction, ‘State of the art’, materials and methods are completely mixed up, the Discussion is extremely short and lacks references and an evaluation of the results with previous findings (of others). In contrast, the Conclusions are way too extensive and contain some literature references.
Before publication can be recommended the manuscript needs to be restructured. In addition, the following comments and question should be addressed carefully:
Title: should be rephrased. Suggestion: ‘Comparison between predicted and measured wood equilibrium moisture contents during monitoring of 12 wooden structures in Switzerland’
Abstract (and elsewhere):
It stays unclear what kinds of structures were examined. Was wood exposed indoors or outdoors?
L12: Should be ‘Mediterranean Sea’, not ‘….climate’
Introduction:
L21: Moisture content should be abbreviated with MC, here and elsewhere in the manuscript.
L32: ‘Durability’ – what kind of? Is it biological durability?
L40: Terminology: what is ‘wet’ – the term usually refers to liquid water (above the hygroscopic range), ‘moist’ would fit better.
L47/48: How did these studies help? Are they relevant for the presented study?
L49 ff: Past tense should be used.
L53 ff: (1) – (3) are different from the 3 climate regions. So, why were they chosen?
L67: What does ‘expected’ mean? Is it calculated, modelled, predicted?
L76: What is the justification/explanation for further organizing the regions?
L94: Which Swiss standard?
L103 ff: Such climate-based decay maps had been produced much more in detail and in particular for Switzerland. Should be discussed much more in detail, see for instance:
Brischke, C., & Selter, V. (2020). Mapping the decay hazard of wooden structures in topographically divergent regions. Forests, 11(5), 510.
Section 2.2: Here the structure becomes extremely blurry, e.g. lines 108-117. Are these Results or Materials and methods?
Table 1: What is ‘theoretical’? Predicted? Calculated?
Table 1: I would not consider Paris, Berlin and Rome being places around the Alps.
L119: What makes RH a convenient parameter?
Figure 3: Does this belong to the Introduction, M&M, or are these results? Where do these data come from?
Section 2.4: Nothing is said about the wood species which were measured. Have species-specific characteristics been determined? If yes, which?
L152: It should be added that the accuracy is remarkably decreasing above fiber saturation.
Figure 4: Dispensable, since very well-established standards methods.
Section 2.5: Again: unclear whether this is ‘State of the art’ or ‘M&M’.
Figure 5: What is shown here, absorption or desorption curves? What about hysteresis? Wsa this neglected? Or were absorption and desorption averaged?
General comment: Standard measures should be abbreviated, e.g. RH (rel. humidity), MC (moisture content), T (temperature), etc.
Section 3.2: It stays unclear (for both methods) if and how the effect of different wood species was considered. Have species-specific resistance characteristics been determined? It is not even mentioned which wood species have been monitored.
Figure 6: What is shown here? Own results? If yes, where d they come from (not at all described). If not, a reference citation is missing. What is shown on the y-axis? Is this Uer,T (equation 7)? If yes, why now named differently? Usually, these kind of resistance characteristics are temperature dependent. Here it stays unclear whether a temperature compensation has been applied (see again eq. 7) or not.
Section 3.3: The information provided is not helpful. Figure 7 and 8 should either be deleted or similar photos should be provided for all 12 structures. More importantly, information is needed about the components where MC had been monitored. Nothing is said about shelter, indoor/outdoor positions, dimensions of the component, measurement location (depth at which the sensors were installed) etc. What was the material (wood species, solid wood or glulam). Without such detailed information it is impossible to evaluate the ‘results and discussion’ part of this paper.
Section 4: The results are generally interesting and well presented, but without knowledge about the applied methods (see comment above) it is almost impossible to assess the quality and interpretation of the obtained results.
However, generally I am missing a comparison between predicted and measured MC.
L 280: What are the reference locations?
Figure 11: How meaningful are the mean values shown in these figures? Is there any statistical analysis of the variation of the different parameters? (see again comment above: how accurate are the predicted measures?)
L287 ff: Is there a measurable effect of the water bodies close to the bridges?
Section 4.3: Terminology – what does ‘expected’ mean? Predicted? Calculated? Or is it a subjective expectations of individuals?
L306: What does ‘in the core of the structural member’ mean? What were the dimensions? How far form the surface was the core?
L318ff: What is the consequence of having moisture contents which are generally 2 %-points higher? What is this impacting on?
Discusion:
Is way too short and includes only one citation (6 references, all already referred to in the introduction). One would expect a more comprehensive discussion of results including an interpretation with help of comparison with previous findings.
Conclusions: here, it is the opposite: way too long and including references (which is unusual).
It is also hard to figure out what the ‘take-home-message’ is for the reader.
References: list is rather incomplete.
L433: Should be ‘Brischke’
Author Response
Thank you very much for your thorough list of comments and suggestions.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
I've included my recommendations in the pdf. Overall, the paper chronicles years of monitoring of critically important wood structures. Except for a few issues, I believe that the authors well presented the manuscript. Keep in mind the novelty of manuscript, although I understand that monitoring is common, but again important research.
Comments for author File: Comments.pdf
Author Response
Thank you very much for your comments. You might notice some significant changes were made to the manuscript. Other reviewers suggested major revisions. I hope this will not be a problem for you.
Author Response File: Author Response.pdf
Reviewer 3 Report
An interesting topic and paper with solid methods of analysis and testing. However, some comments and suggestions:
Abstract:
It is a bit irritating when using the term ‘relative humidity in a structure’; isn´t it rather the moisture content which is meant here? Would suggest to edit this formulation.
Introduction:
Page 1, line 22: Better ‘service life’ then ‘lifetime’
Page 1, line 25: Is the ‘surrounding climate’ meant here or the ‘material climate’?
Page 1, line 30: The authors should add an information for what the climate differences need to be ‘accounted for’.
Page 1, line 32: What is precisely meant by durability here? Is it the resistance against wood-destroying organisms or is it just the service life of the timber until it fails? Why and when does it fail. Please, define this term ‘durability’ precisely.
Page 1, line 33-34: Preferred to do what? Hide moisture away from wood structures? Please edit and add some information here.
Page 1, line 40: Better ‘where it is exposed’ or ‘where it is installed’
Page 1, lone 41: The context is not clear in this sentence: Which structural damages and where had they been observed?
Page 2, line 47: What does ‘building type’ precisely mean and how do the building types differ with regard to the wooden design elements?
Page 2, line 49: ‘evaluated’ not ‘evaluate’
Page 2, line 50: What does ‘heating’ mean?
Page 2, line 52: ‘focused’
Page 2, line 54: Could the term ‘long periods’ be quantified in days/weeks/months?
Page 2, line 53-56: Is it possible to differentiate condition 1, 2 and 3 by the same parameter, e.g. the relative humidity, the altitude? Yet, it seems a bit inconsistent and the reader does hardly get the relationship between these three conditions/points and why the separation was made like it is.
State of the art:
Page 2, line 66-67: Something is wrong with the sentence structure; please edit.
Page 3, line 89: Please differentiate hot and warm summers by providing a temperature range.
Page 3, line 94: ‘…service class and as a consequence the service life of a wooden structure.’
Page 3, line 95: Please add that the equilibrium moisture content of wood is meant at this place.
Page 3, line 99: Better ‘Relative humidity and temperature data’
Page 4, line 116-117: The table´s heading is very unprecise. EMC in which kind of building element? Which type of design? Outdoor exposed wood? etc.
Page 5, line 145-158: The authors should add some more details and basic information on how the two described methods for MC measurements in wood work and how the MC in wood is calculated on the basis of theses measurements (resistance and ambient climate).
Page 6, line 178-180: Perhaps it may help and make the effect of the temperature on the sorption isotherms of wood more obvious, when both sorption isotherms are illustrated in one graph or as a further idea, a differential curve originating from the MC differences at a given RH could be shown to make the effect of the temperature more obvious.
Data Acquisition and Analysis
Page 9, line 246: What does ‘these’ in this sentence refer to?
Figure 10 and 12: When using trend lines please insert the function and R².
Figure 11: In the humidity-moisture figures: It is not 100 % clear what the different coloured symbols stand for. Is orange = December and blue = June, like in the temperature-humidity figures?
Discussion
Page 13, line 333: Please edit the sentence and use another term then ‘makes sense’.
Conclusions
The conclusions part is quite long and includes a lot of summary of the results and discussion part. The authors should shorten the conclusions and shortly put together the key findings and answers on their research questions and avoid to repeat information, which has been listed already.
Author Response
Thank you very much for your thorough list of comments . The authors believe that the quality of the manuscript has improved by following your suggestions.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscript improved, but the main flaw has not been addressed:
Still, information about measurement positions is lacking (depth, component dimensions etc.). Probably, this was different for the various structures - so detailed information is required. As a consequence the interpretation of results (i.e. the measured MC) is almost impossible. This becomes evident during the dicussion. For an outside person (reviewer or reader) it is impossible to judge the different findings presented in the paper. Why not simply describing where exactly the measurements were taken? Just stating that it were 'sheltered components' is surely insufficient.
Further issues need to be addressed:
Botanical names of wood species should be provided: e.g. Scots pine (Pinus sylvestris).
L103: RH is a dominating factor only for un-exposed wooden components. Otherwise the effect of RH is overruled by the effect of precipitation.
L 150: "The risk of driving rain in the Alps is comparable to that found in Germany" - should be 'similar', not comparable. Further, it is conbfusing: Parts of the Alps are located in Germany. Which part of Germany is compared with which part of the Alps?
Abbreviation MC is not consistently used.
Figure 7: should be deleted since it does not provide any relevant information.
Author Response
Thanks again for your thorough reading and helpful suggestions to improve the manuscript.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
I surely agree that the effect of the measuring depth on wood MC is significantly smaller in sheltered wood compared to exposed wood. Using only average MC instead of single values is further masking such effects, but does not allow to neglect the effect of the measuring depths. Several previous studies showed that there are significant effects - and this cannot be surprising. If the authors can prove the opposite (based on own measurements) they should simply present the respective data. That would justify the simplification.
If not, this shortcoming needs at least to be discussed intensively. Comparing data taken at depths between 10 and 200 mm is comparing apples with pears. The differences in MC, e.g. 1% between Inner and Southern Alps (L410) need to be set into perspective.
Author Response
Thanks again for your suggestions. We added cross section sizes in Table 2 and formulated some conclusions more precisely.
Author Response File: Author Response.pdf
