Building fire damage:

Fire damage assessment, fire damage repair priorities, fire damage minimization. This fire damage home page provides links to in-depth articles on a variety of building defects, systems, or components that are associated with extra risk of fire; we also discuss fire damage assessment.

This article series also discusses how fire damage and mold damage might be related in a building. In a separate article we also discuss problems of wildfire damage risks to homes and how to minimize the risk of wildfire damage.

Fire Damaged Buildings: assessment, safe building entry

Our photo at page top shows a Rhinebeck NY home that was destroyed by fire caused by an electrical cord that had been run beneath the carpeting.

Scope of Building Fire Damage, & Comparing Fire Damage to Buildings with Mold Damage

Our fire damage photographs how two different extents of fire damage in the roof and attic of a New York home.

Below we discuss damage and mold contamination questions following a fire in two different structures.

How Should Previous Fire-Damage Be Reported to a Home Owner or Home Buyer?

Question: this home suffered a fire - what should be reported?

I inspected a home earlier today and the exposed joists in the boiler room (should be covered with fire rated materials) was charred. The areas which i pocked at seemed that damage was just on the surface.

There were also signs of fire damage in the home's attic.

Per listing agent the fire occurred prior to current owner occupancy.

Beyond making a request to the present home sellers that they get more details from the owner of the home at the time of the fire and a suggestion to consult with local building department regarding history of damage and documented measure of repairs taken, what other questions should a home owner or buyer of this home pursue?

Reply:

The request for information about who did what regarding repairs to prior fire damage that you suggest is important and useful.

In my experience, however, the depth of information that may be on file at a local building department concerning post-fire repairs may vary considerably from one building code enforcement jurisdiction to another.

An inspection report, such as a home inspection for an owner or buyer, concerning a building where there is evidence of a prior fire should make several points very clear in order to protect the building occupants and owners from a costly or dangerous surprise.

The responsibility of the inspector, even if that person cannot complete the fire damage/repair assessment includes at least the following:

1. There is evidence of a previous building fire and, presumably repairs to that damage
2. The full extent of damage and repair cannot be given by a normal condition-of-property inspection, such as a pre-purchase home inspection report, and some additional information gathering and possibly also some additional property assessment are in order.
   
   We do not asset that the following warning topics mean that the building requires additional repair work, but these are topics for which an owner or buyer should be informed and alert. Ideally the records and receipts for post-fire repairs will address all of these and other site conditions affected by a fire.
3. Structure: When there has been a building fire the substantial question is whether or not adequate repairs and renovations were made afterwards.
   
   Watch out: beyond the obvious concern with the extent of fire damage to wood structural members (and sheathing), post-fire assessment must consider as well the condition of structural connectors.
   
   Following a fire some structural connectors, such as metal truss plates and epoxied bolts or other framing connectors, may be damaged by the heat of fire or by post-fire corrosion following heat, loss of galvanized coatings, and water or other chemicals used to extinguish the fire.
   
   In addition, modern glulam or LVL timbers may have been weakened by the effects of heat on their binder or glue even when the members don't look charred to the naked eye. (Avent 1984) (Buchanan 1994)
   
   All connections will require detailed inspection to assess their load bearing capacity. in his discussion of large fire-damaged timbers, Williamson (1982a) notes that the effect of fire on the strength of any connection is very difficult to determine without a thorough investigation of the affected connection, since the amount of damage is dependent on the quantity of metal and the surface contact of metal with fire along with other factors.
   
   There may also be possible chemical damage from the corrosive effects of fire residues. Metal roof supports, ceilings, and other structural members are vulnerable to long-term acid attack from fire residues (King 2002).
   
   Exposed metal connections provide a means for heat conduction into the wood (Fuller et al. 1992), ... - US FPL cited in detail below.
4. Roofing: if a fire originating inside the building interior did not burn through roof but if the roof covering, such as asphalt shingles, was heated to a high temperature, the roof covering may have been damaged and may have a reduced remaining life.
5. Electrical system: Records may show that some or all electrical wiring was replaced within in area of the fire and areas exposed to high heat - or perhaps not.
   
   There is a more hidden risk that could be serious if not addressed. Heat exposure, for example, can damage electrical wire insulation, making it less safe in the future.
   
   Similarly, heat-damaged devices, receptacles, switches, AFCIs, GFCIs, circuit breakers, or other electrical controls may leave them looking normal but nevertheless unreliable and thus unsafe.
6. Mechanical system: The same questions pertain for heating and air conditioning equipment, pumps, motors, and appliances, as raised above.
7. Plumbing system: heat-damaged plastic supply or drain piping, if not replaced, may be at greater risk of a future break, leak, and water-related damage.
8. Mold contamination: as we discuss
   
   at FIRE RELATED MOLD CONTAMINATION,
   
   the spread of water used in the extinguishment of a fire or of rain or melting snow and ice post-fire if a building's roof and exterior were damaged, can lead to mold contamination in building ceiling, wall, or floor cavities that were wet even if they were nowhere near the actual fire.
9. Smoke Damage & Odor Issues: may remain in the building even after its structure and other components have been repaired and replaced. Fire-damage restoration companies can offer help in finding, cleaning, removing, or sealing materials giving a remaining smoke or fire odor problem.

An inspection report that fails to make an effort to make the client understand the concerns and what to do about them would not be living up to the standard of public trust that pertains to home inspectors, engineers, architects, and other building professionals.

As one can read in the articles I cite below, even an experienced and trained licensed professional engineer ultimately is going to have to use her experience and judgment to form an opinion about fire damage to building components.

While there procedural guidelines, as the articles I cite suggest, even a engineer experienced in wood frame construction can't use standard tables or measures to evaluate fire-damaged wood - those members in that condition don't appear in framing span tables.

And in-situ strength testing of fire damaged structural beams, studs, joists, etc. to determine their point of failure is simply not feasible.

So an intelligent eye and mind applied to the situation by an experienced inspector can be credible in forming useful observations about conditions in a fire-damaged wood-frame structure.

I attach below two US FPL articles that confirm the view that the structural integrity of lightly-charred solid wood members is usually not compromised.

If probing finds only very superficial charring on wood structural members and if there is no evidence of sagging, breaking, etc. they're probably OK; often we can note that some members were already replaced and others left in place, suggesting that a contractor made a decision, at the time of the work, on which needed replacement.

A separate question, discussed

at PYROLYSIS EXPLAINED,

is whether or not heat-exposed wood materials have henceforth a lowered point of combustion and thus lower future fire-resistance.

Wood Structure Fire Damage Assessment Research & References

This illustration shows the various zones in fire-damaged structural wood members, adapted from the US FPL article cited in detail just below.

[Click to enlarge any image]

• ASTM International , ASTM E 119 (2000) Standard Test Methods for Fire Tests of Building Construction and Materials, includes a standard test method for determining the fire-resistance rating of a structural member or assemblies for building code purposes. Source: https://www.astm.org/Standards/E119
  Summary Excerpts:
  
  4.1 These test methods are intended to evaluate the duration for which the types of building elements noted in 1.1 contain a fire, retain their structural integrity, or exhibit both properties during a predetermined test exposure.
  
  4.2 The test exposes a test specimen to a standard fire controlled to achieve specified temperatures throughout a specified time period. When required, the fire exposure is followed by the application of a specified standard fire hose stream applied in accordance with Practice E2226.
  
  The test provides a relative measure of the fire-test-response of comparable building elements under these fire exposure conditions. The exposure is not representative of all fire conditions because conditions vary with changes in the amount, nature and distribution of fire loading, ventilation, compartment size and configuration, and heat sink characteristics of the compartment.
  
  Variation from the test conditions or test specimen construction, such as size, materials, method of assembly, also affects the fire-test-response. For these reasons, evaluation of the variation is required for application to construction in the field.
• Avent, R. Richard and Camille A. Issa. 1984. Effect of fire on epoxy-repaired timber. Journal of Structural Engineering. 110(12):2858-2875.
• Buchanan, A. and D. Barber. 1994. Fire resistance of epoxied steel rods in glulam timber. In: Proceedings, Volume 1, Pacific Timber Engineering Conference; 1994 July 11-15; Gold Coast, Australia, Fortitude Valley MAC, Queensland, Australia: Timber Research and Development Advisory Council. pp. 590-598.
• Cabaleiro, Manuel, Carlos Suñer, Hélder S. Sousa, and Jorge M. Branco. "Combination of laser scanner and drilling resistance tests to measure geometry change for structural assessment of timber beams exposed to fire." Journal of Building Engineering 40 (2021): 102365.
  Abstract
  A structure may be totally destroyed due to a fire, but often it is only partially damaged and parts of it may still be salvaged and reused. For buildings with significant historic and cultural value, it is of utmost importance that these elements, which were only partially damaged, can still be recovered as to preserve the authenticity of the structure. In the case of timber elements after a fire, it is common to find damage on the cross-section exterior part, whereas the inner part presents still a non-damaged section.
  
  Therefore, the element is often found with an exterior irregular shape, either due to its original shape prior decay or due to the exposure to fire, that does not coincide with the inner residual cross-section. Moreover, it is essential to perform a preliminary safety analysis to verify which elements can be preserved and to what extent interventions could be needed. The objective of this work is to apply a methodology that allows to calculate the residual cross-section of partially burnt timber elements structures as to calculate the resistant and apparent sections for geometry assessment and to implement that information in three-dimensional structural models.
  
  For this purpose, this work proposes a methodology based on a combination of drilling resistance tests together with laser scanner measurements. The methodology was first tested and calibrated within a controlled laboratory environment and then validated onsite using elements from a building exposed to a past fire. The Casa de Sarmento (Sarmento's House) in Guimarães (Portugal) was used as case study, where various structural damages due to a past fire were found.
• Churpek, Mark, P.E., EVALUATION OF FIRE‐EXPOSED STRUCTURAL MEMBERS [Power Point-PDF] (2013) Janney, Elstner Associates, Inc. Email: mchurpek@wje.com retrieved 2018/10/11, original source: http://seaoo.org/downloads/Presentations_CONF/seaoo_2013_conference___fire_exposed_structural_members__churpek_rev.pdf
• Gerhards, C.C. 1982. Effect of moisture content and temperature on the mechanical properties of wood: An analysis of immediate effects. Wood and Fiber. 14(1):4-36.
• Gypsum Association, FIRE RESISTANCE DESIGN MANUAL (Sound Control) GYPSUM SYSTEMS [PDF] (2009) Gypsum Association, retrieved 2021/07/07
  
  This Manual is a convenient and useful specification aid for anyone concerned with the design, construction, or inspection of fire resistive and sound control systems. Design information is quickly and easily determined. Comparison of these characteristics allows the user to be more accurate in meeting design and code requirements. The data provided are especially useful to builders, architects, code officials, fire service, and insurance personnel.
• Hakkarainen, Tuula, and Tuuli Oksanen. "Fire safety assessment of wooden facades." Fire and Materials 26, no. 1 (2002): 7-27.
• Janssens, M.L. and R.B. White. 1994. Temperatures profiles in wood members exposed to fire. Fire and Materials. 18, 263-265.
• Knudsen, R.M. and A.P. Schniewind. 1975. Performance of structural wood members exposed to fire. Forest Products Journal. 25(2):23-32.
• Kukay, B.;White, R.H.; Woeste, F. CHAPTER 6: FIRE DAMAGE OF WOOD STRUCTURES. IN: INSPECTION, TESTING AND MONITORING OF BUILDINGS AND BRIDGES. National Council of Structural Engineers Association. Chapter 6. ISBN: 978-1-60983-198-1; 2012; pp. 73-83.
  Introduction:
  Depending on the severity, fire damage can compromise the structural integrity of wood structures such as buildings or residences. Fire damage of wood structures can incorporate several models that address
  
  (1) the type, cause, and spread of the fire,
  
  (2) the thermal gradients and fire-resistance ratings, and
  
  (3) the residual load capacity (Figure 6.1).
  
  If there is a danger of local collapse, immediate concerns about the stability of free-standing residual parts of a fire-damaged building will need to be addressed very quickly [1]. Assuming that the structural fire is contained, then under certain circumstances time becomes less of an issue.
  
  The investigator should employ engineering judgment to identify those in-service members that are to be replaced, repaired, or can remain in-service as they are.
  
  Such judgment will likely be based on the visual inspection of damaged members, connections, and any protective membranes. In light-frame construction, wood assemblies are typically shielded from flames and heat by gypsum board and insulation; these greatly increase the amount of time required for the onset of charring.
  
  Potentia lmethods for nondestructive evaluation of structural properties of a fire-damaged wood member are described below.
• National Fire Protection Association (NFPA). 1998. Guide for fire and explosion investigations. NFPA 921. Quincy, MA: NFPA. 167 p.
• Ross, Robert J., Brian K. Brashaw, and Xiping Wang. "Structural condition assessment of in-service wood." Forest products journal. Vol. 56, no. 6 (June 2006): pages 4-8. (2006).
• Salih Amin, Rizgar, STRUCTURAL APPRAISAL FOR FIRE DAMAGED BUILDINGS [PDF] retrieved 2018/10/11 original source: http://keu92.org/uploads/Search%20engineering/STRUCTURAL%20APPRAISAL%20FOR%20FIRE.pdf
  Excerpt from conclusions:
  
  ... all structures that have been subjected to fire should be evaluated in systematic manner, to determine the extent of the damage and a necessary repair strategy if required.
  
  The intensity and duration of the fire needs to be determined by observing the damage to the building and testing the materials and structural elements.
  
  These evaluations, combined with good engineering judgement, allow for effective and economical repairs to be established.
• Schaffer, E.L. 1973. Effect of pyrolytic temperatures on the longitudinal strength of dry Douglas-fir. ASTM Journal of Testing and Evaluation. 1(4):319-329.
• US FPL, POST-FIRE ASSESSMENT OF STRUCTURAL WOOD MEMBERS [PDF] Chapter 4 in Wood and Timber Condition Assessment Manual, U.S. U.S. Forest Products Laboratory, retrieved 2018/10/11, original source: https://www.fpl.fs.fed.us/documnts/pdf2005/fpl_2005_ross005.pdf
  
  Excerpts: Since the interior of a charred wood member normally retains its structural integrity, large structural wood members often do not need to be replaced after a fire.
  
  Engineering judgement is required to determine which members can remain and which members need to be replaced or repaired.
  
  Due to the lack of established methods to directly determine the residual capacity of damaged wood members, a systematic approach starting with the assessment of the likely fire exposure is recommended.
  
  Assessment includes visual inspection of damaged members, visual inspection of connections, and visual inspection of any protective membranes (i.e., gypsum board).
  
  Potential methods for nondestructive evaluation of structural properties of a fire-damaged wood member are discussed after a brief review of the degradation of wood when exposed to fire.
  
  ...
  
  For wood members that have charred, the char layer can be easily scrapped off. Obviously, any charred portion of a fire-exposed wood member has no residual load capacity.
  
  The wood beneath the char layer has residual load capacity; but, this residual capacity will be less than the load capacity prior to the fire.
  
  Members that have only visual smoke damage or slight browning of the surface also have significant residual load capacity.
• US FPL, B. Kukay, R. White, and F. Woeste FIRE DAMAGE OF WOOD STRUCTURES [PDF] Chapter 6 includes "Direct determination of fire-damaged timbers" and other step by step procedures.
  Excerpts:
  
  Depending on the severity, fire damage can compromise the structural integrity of wood structures such as buildings or residences.
  
  Fire damage of wood structures can incorporate several models that address
  
  (1) the type, cause, and spread of the fire,
  
  (2) the thermal gradients and fire-resistance ratings, and
  
  (3) the residual load capacity (Figure 6.1).
  
  If there is a danger of local collapse, immediate concerns about the stability of free-standing residual parts of a fire-damaged building will need to be addressed very quickly [1].
  
  Assuming that the structural fire is contained, then under certain circumstances time becomes less of an issue.
  
  The investigator should employ engineering judgment to identify those in-service members that are to be replaced, repaired, or can remain in-service as they are.
  
  Such judgment will likely be based on the visual inspection of damaged members, connections, and any protective membranes. In light-frame construction, wood assemblies are typically shielded from flames and heat by gypsum board and insulation; these greatly increase the amount of time required for the onset of charring.
  
  Potential methods for nondestructive evaluation of structural properties of a fire-damaged wood member are described below.
• White, Robert H., and Brian M. Kukay, POST-FIRE ASSESSMENT OF STRUCTURAL WOOD MEMBERS [PDF] Wood and Timber Condition Assessment Manual (2014): 33, General Technical Report FPL–GTR–234 retrieved 2021/09/21, original source: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.692.51&rep=rep1&type=pdf#page=41
  
  Because the interior of a charred wood member normally retains its structural integrity, large structural wood members often do not need to be replaced after a fire. Engineering judgment is required to determine which members can remain and which members need to be replaced or repaired.
  
  The lack of established methods to directly determine residual capacity of damaged wood members dictates a systematic approach, starting with assessment of likely fire exposure. Assessment includes visual inspection of damaged members, visual inspection of connections, and visual inspection of any protective membranes (such as gypsum board).
  
  Potential methods for nondestructive evaluation of structural properties of a fire-damaged wood member are discussed after a brief review of the degradation of wood when exposed to fire.
• White, Robert H. and M.A. Dietenberger. 2001. Wood products: Thermal degradation and fire. In: Encyclopedia of materials: Science and technology. New York: Elsevier Science Ltd.
• White, Robert H., Steven M. Cramer, and Deepak K. Shrestha. 1993. Fire endurance model for a metal-plate-connect wood truss. Res. Pap. FPL-RP522. Madison, WI, U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 12 p.
• Williamson, T.G. 1982a. 4.5.4 Rehabilitation of fire-damaged members of Chapter 4 Evaluation. In: Evaluation, maintenance and upgrading of wood structures-A guide and commentary. New York: Arnerican Society of Civil Engineers. pp. 172-178.
• Williamson, Thomas G. 1982b. 8.8 Rehabilitation of fire-damaged timber-The Filene Center of Chapter 8 Recycling old structures (Case histories). In: Evaluation, maintenance and upgrading of wood structures-A guide and commentary. New York American Society of Civil Engineers. pp. 417-422.

Post-Building Fire Mold Contamination

This discussion about when, where, how and why a building may become mold contaminated following a building fire has moved

to FIRE RELATED MOLD CONTAMINATION

Wildfire Damage Prevention Advice for Homeowners

This topic has moved to its own page

at WILDFIRE DAMAGE PREVENTION for HOMES - Recommendations about Trees, Shrubs, other Vegetation around the building to reduce wildfire damage risks

...

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-09-21 by inspectapedia.com.moderator (mod) - is this blackened wood fire damage or mold?

@paula.kolek,

From your photo I'm not sure we're seeing fire damage: that black could be "charring" of the wood surface of a beam or other wood material, but the light colored wood and the shallowness of the black looks more to me as if that was a fungal or mold growth.

If there is charred wood in your building from a prior fire, that could explain, at least in part, the presence of white mineral effloresence on the building brick surfaces: effects of water used to extinguish a fire.

So is that wood (beam?) seriously damaged by fire?

An engineer charged with assessing the structural integrity of fire-damaged wood posts and beams, rafters, trusses, etc., will inspect the extent of fire-damage to wood beams by comparing the original dimensions to those of the remaining material, after allowing for and discounting the thickness of the charred portion.

Unlike steel members heat doesn't have as much effect on the remaining, un-burnt-wood except perhaps the effects of pyrolysis that might lower the combustion point at a future fire.

It's worth noting that research on the assessment of structural components after a fire has published much more on assessing steel and concrete than wood. But there is research on assessment of fire-damaged wood structures and other wood building components such as wood facades.

See "Wood Structure Fire Damage Assessment Research & References" in the article above - on this page.

This Q&A were posted originally at EFFLORESCENCE FAQs

A relationship between water damaged and charred wood or fire damage is, of course, the effect of massive amounts of water on a building when water has been used to extinguish a building fire.

On 2021-09-21 by Paula Kolek: is this black "charring" flakes off - probably not much damage?

RE-posting from a discussion of water damaged masonry that included what the reader appeared to describe as charred wood structural member:

paula.kolek

@inspectapedia.com.moderator, Thanks! The integrity of the wood beam seems fine and strong. It's just that one side has a lot of charing that still flakes off as dust and larger pieces, but maybe we can get them to seal that as well. I appreciate your help.

On 2019-07-22 by (mod) - this fire damaged building is unsafe

Anon

If you think that the building is a danger to the public you should take that information to your local fire, police, or building department.

You're welcome to post photos here (one per comment)

On 2019-07-22 by Anonymous

There is a burn down factory in farmingdale new York name Grumman factory it falling down and the lazy political party are not doing notting about it just like a power outage .

The building is falling down and the stupid political party sit down an just talk garbage long island rail road next to who ever read you need to see abandon run down building

...

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Citations & References

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