Thursday, October 31, 2013

Old Cottage and the Sea, Part 3 - Floodproofing

Resident Griffon monitoring the renovations.

  1. Moving Forward
  2. Getting Rid of Mold
  3. Dating the Layers 
  4. Tackling the Foundation
  5. Then, the Flooring
  6. Floodproofing the Walls
  7. What to do about the electrical outlets?
  8. More, More Ventilation!
  9. Finally, "Floodproofing" the Furnishings
  10. Almost Done
  11. Next Steps: the Exterior

It is the one-year anniversary of Super Storm Sandy. We marked the occasion with a gathering of friends and family at a “Stronger than the Storm” party. The best part of the party was that it took place in the same cottage that was in such a sorry state last year at this time.  (If you are new to this story, the first chapters of this saga can be found in Part 1 and Part 2 of this series.)

It’s been a long year of hard work, patience, research, and conversation to settle on how best to retrofit this historic cottage to be “more resilient” – the most overused phrase of 2013. But after carting out a hundred heavy bags of soggy, smelly wallboard and carpeting, I, like Scarlett O’Hara, shook my fist at the stormy skies and vowed, “Never again!”

So, instead of just putting back the same materials – plywood, gypsum wallboard, fiberglass batt insulation – I prepared to “wet floodproof” my house, i. e., make it less susceptible to damage by using flood resistant materials.

FEMA has published an enormous body of guidance on flood mitigation strategies –some of the documents are listed below – but there is nothing as helpful as putting the theories into practice for yourself. Here are a few critical principals to keep in mind in retrofitting a building to be more “resilient”:
  1. Use flood resistant materials, e.g. dense hardwoods, ceramic tile, pressure treated wood, concrete wallboard, and closed-cell foam  insulation boards (avoid non-marine plywood, wall-to-wall carpet, gypsum wallboard, and fiberglass insulation batts, among other things);
  2. Furnishings should be resistant to water damage or easily elevated;
  3. Elevate all utilities, HVAC, ductwork, electrical outlets and panels, and appliances above the Base Flood Elevation plus whatever additional height is required under your local floodplain ordinance; and
  4. Ventilate, ventilate, ventilate! Incorporate cavities in the walls and floor with openings at both ends so that air can circulate, which helps the structure dry out quickly after a flood.
These principles aren’t appropriate for every flood zone, mind you. In the “V” zones, where storm surge and wave action cause the most damage to structures, you are well advised to follow the elevation guidance for your buildings. But the “A” zones, where the cottage is located, are only affected by rising water, not wave action. The water rises, the water retreats.

Floodproofing is a way that structures in “A” zones can reduce their losses and preserve their structures. Please note that we are not talking about the new flood insurance rates at the moment, just the physical retrofitting of existing structures to reduce flood losses. The new insurance rates are the subject of legislation now moving forward that will delay the effective date of the new rates until further study is done.

Moving Forward

Patience is not only a virtue during the first rebuilding phase after a disaster such as Super Storm Sandy - it is a requisite. With some 346,000 housing units damaged or destroyed in New Jersey, architects, engineers, contractors, and building supply companies were scrambling for many months after the storm – even now there is no shortage of work for anyone in the building industry, as many people have had to wait for funding before they can start construction.

As for me, thanks to a great public adjuster, I received my insurance proceeds by January and was ready to find a contractor. I didn't have to look far – just next door was a great builder Joel Brennan, and his business partner Bill Craig, both long-time Ocean City residents. Joel and Bill knew only too well what the humid, salty air of the coast requires in terms of building techniques. We started formulating our strategy for the cottage months before we could actually start work.

Getting Rid of Mold

Before we began anything else, however, it was best to test for mold. Although we had removed all the saturated materials – flooring, carpeting, and insulation – we discovered that sometime several layers of renovations had been laid, one on top of another, over the course of some 100 years. 

During the preliminary cleaning out, we had noticed traces of mold between the layers – we didn't know whether it was freshly sprouted or whether it was something left from a previous inundation. 

We called in the experts. The environmental testing company found the highest readings were in the dining room, which was a surprise, given the polyglot of materials we had discovered in the living room. 

A big issue, we discovered during demolition, was that the 1913 three-sided bay in the dining room has been insulated with newspaper, which is a good medium for mold growth. 

Newspaper used as insulation in wall.
The second troublemaker was the high-rag content paper installed between the studs and the clapboard on the north wall – likely an early form of wind barrier. It was also covered with spots of black mold.

High rag content paper covered with mold.
Before the ServPro mold remediation team came, we removed everything down to the original wood framing, disposed of the moldy paper, and cleared out the debris. During the demolition, we discovered an early board and batten wainscot, perhaps from 1913.  

Board and batten wainscot under drywall in dining room.
We dated the wallboard covering over this nice wainscot as being installed in 1959 based on the amusing sign and penny from that year left on top of the paneling.

Worker mementos from a prior renovation found within the layers.
Since these layers created spaces in which mold could hide, and were constructed of materials that were not flood-proof, I decided they all had to go.  After recording the layers in photographs, including measurements penciled on the wall, we took it all down to the wood studs. Once the rooms had been treated, the air quality improved dramatically.

Dating the Layers

So little was left of the historic fabric throughout that I decided that, rather than trying to preserve these fragments, a better approach was to photo-document all of the layer remnants as we uncovered them, and then take everything down to the original ca. 1885 wood framing. From there, we could begin to develop a rational approach to reconstructing the interior.

This strategy provided an excellent opportunity to date the previous interventions with some accuracy.The oldest layer was plaster and lath, but only spotty remnants of it remained. The dining room seemed to be the only room with interventions dating from 1913 (the date the earlier 1-story kitchen wing was constructed). The sections of fake wood paneling in the living room dated probably from ca. 1960 - about the same time that the front hollow-core door with the diamond-shaped window had been installed. (I regretted losing the funky front door, but it had warped after the flood and no longer closed properly. It was replaced by a fiberglass version - perhaps more appropriate in design and certainly more resilient, but less interesting.)

Front door (ca. 1960), which had warped after the flood
and would not close.
Over the top of all that was the top layer of gypsum wallboard – “drywall” – evened out with occasional pieces of green board, a moisture resistant wallboard. On some of the layers we discovered the high water mark from a previous flood, very near to the current flood line. 
Layers of the various materials built up on the walls, saturated.

If nothing else, this retrofitting has permitted a more complete understanding of the evolution of the cottage, pieced together from the fragments of past renovations. It also has provided the opportunity to ruminate on the seeming conflict between preserving the historic integrity of a series of interior layers and preserving the essential architectural form of the historic cottage -- an increasingly rare specimen of the architectural heritage of Ocean City. But then that's a subject for another essay.

Tackling the Foundation

Given the significance of this “wooden tent” to Ocean City, its relationship to the landscape was important to preserve. As a historic property, it was permitted to remain at the historic height when I built the new addition, a variance from the floodplain ordinance. This means, of course, that it is more susceptible to flood damage, since it is about four feet below the “Base Flood Elevation” for that neighborhood.

When it was moved to the site around 1905, the house was set down on ungrouted concrete blocks; the floor’s 2” x 6” pine floor joists were just about 6 inches above wet sand; on top of the joists were tacked small panels of ordinary plywood. When you entered the house, it always smelled a little like wet sand on the bay – a little mossy, a little fishy. I always thought it was just the way beach houses smelled.

Wet sand below floor framing (LR).
The porous foundation system actually worked pretty well in a flood – the water percolated up through the sand and through the concrete blocks. No threat of “hydrostatic pressure” crushing the foundation, since the pressure was always equalized between the interior and exterior. However, if the floodwaters got high enough, there might be a tendency of the house to float off the foundations, since the walls didn’t seem to be anchored to much of anything secure. To remedy the instability of the foundation, the moisture and mildew problem, and the buoyancy issues, we called on a structural engineer to take a look. 

Lamont “Butch” Czar, P.E., based in Egg Harbor Twp., has spent most of his professional career on projects at the Jersey Shore. Retrofitting a historic building can sometimes be tricky, so finding someone willing to take the time is a rarity – especially when there are so many more pressing projects along the coast after Sandy.

Butch developed a strategy that would reinforce the foundation, replace the wet sand and floor joists with a concrete slab. This would still allow the water to flow in and out of the structure during a flood, since there is really no way to keep the water out of these old places, and make the house drier. His design took out every other concrete unit and inserted a footing, which became part of the slab. 

Diagram of new foundation and slab. Courtesy Czar Engineering, Inc.
When the framing was fully revealed in the living room during the preparation of the pouring of the slab, the story of how this fragile building had been repaired over time became clearer. Deteriorated or cracked studs had been sistered with new 2 x 4s; a few inches of the presumably deteriorated ends of some of the studs on the north wall had been cut back to good wood, then supported by a platform of a longitudinal 1-by and blocks of 2x4s turned on the vertical.

Existing condition of structural framing at foundation.
We corrected this condition by installing a new P.T. sill on both the north and south foundation walls, adding hurricane clips that would tie into the concrete slab and foundation when it was installed. 

New sill reconstructed with P.T. boards.
The changeover from wood joist system to a concrete slab was not without some philosophical hand-wringing over the elimination of a historic structural system. Eventually, I rationalized the change as follows: 1) little of the original flooring framing was extant, having been apparently repaired and rebuilt many times in the past; 2) the damp microclimate under the floor encouraged wood rot and mold; 3) the foundation of loose masonry units was not optimum for structural stability; and 4) the superstructure was not secured to the foundation. All of these conditions needed to be addressed for the long-term preservation of the structure. Finally, the change to slab would not be visible, and therefore would not detract from the historic character of the building. 

Then, the Flooring

Once the slab had been poured and dried, it was time to install the new flooring system. You'll be hearing a lot about “venting” - allowing the air to circulate within the structure. Allowing the building to breathe will help it dry out more quickly in the next flood, and generally is healthier, both for the wood framing and the occupants of the building.

Venting strategies started in the flooring system. The mahogany dining room floor installed in 2005 had come through the flood relatively unscathed, not only because the wood was extremely dense, but we had left a margin at the edge of the room for the wet boards to expand without buckling the floorboards. The joists were pressure-treated (P.T.); the subfloor was marine-grade plywood; and finally, the floorboards were installed over P.T.  2" x 4" boards (sleepers). The typical paper layer over the subfloor was eliminated – paper being one of those absorbent materials that provide a good home for mold.

Installation of sleepers onto new concrete slab in living room.
We used this same approach in the living room, except with a new twist. A concrete slab is often cold and damp, so the airspace between the sleepers would not effectively dissipate the dankness. To alleviate the issue, the contractors laid a heated padding system between the sleepers, which would be covered with a skim coat of concrete. 

Heating pad installed between sleepers.
The assembly would still leave about 1” clearance between the slab and the floorboards where air could circulate. The temperature of the heating element is regulated by a wall-mounted thermostat, which will maintain a relatively low temperature (65 degrees plus or minus), just to take the edge off the cold coming from the concrete, rather than being a source of ambient room temperature.

Finally, over the sleepers and heat assembly, we installed the new mahogany flooring (see below for finished product).

Floodproofing the Walls

The walls of the cottage presented an interesting challenge. FEMA’s guidance talks about installing a break between the upper wall (above the BFE) and the lower wall (that is likely vulnerable to floodwater). Above the break, you can use typical building methods (fiberglass insulation, gyp board, etc.). Below the break, you use flood resistant materials (concrete wallboard, closed cell foam board insulation, held away from the exterior wall to create a venting cavity). The break between the two sections is covered by a chair rail. To create a flow of air behind the insulation, the wallboard ends about 3-4” above the floor, which is covered by the baseboard. After a flood, the chair rail and baseboard are removed, and the air circulates behind to dry out the interior of the wall.

FEMA illustration showing how to construct a floodproof wall.
We modified this FEMA guidance for the cottage. Given rising seas, who knows what the height of future flood levels will be? We decided to use concrete wall board and closed cell insulation board for the entire height of all walls in areas that were below the BFE, leaving a space at the top and bottom of the wall, open to the exterior wall.  This included the historic rooms (dining room, living room), as well as the hyphen between the addition and the historic rooms.  We installed green board (moisture resistant) on the ceiling for added measure.

Venting slots behind baseboard and cornice.
For air circulation, Joel devised an innovative method to introduce air circulation between the cornice (molding at the top of the wall) and a removable baseboard. The cornice was cut wide enough to cover the 4” gap and set out from the wall plane, leaving a passive opening that could remain in place after a flood. 
Venting slot under cornice.

Joel designed the baseboard so that it, too, covered the gap that was open to the exterior wall, but only a small piece of board, held in place by screws, would have to be removed to open the circulation after a flood. Until it had to be removed, a cord of closed cell foam insulation was set into the baseboard opening to seal the opening, which prevented the cold air from blowing back into the house. 
Venting slot in baseboard with removable insulating cord.

In the event of a flood, the single board would be removed and the cord plucked out, opening the air circulation through the wall cavity. The goal is to reduce the amount of material that must be thrown in the dumpster after a flood and minimize the amount of human intervention needed to help a building dry out. Having put my hand into the opening before it was closed off, I can report that the air was moving well through the cavity - in fact, it was downright breezy in there.

What to do about the electrical outlets?

In the frenzied preparations before evacuation, I had neglected to turn off the main switch in the electrical panel in the house - an omission that might have had terrible consequences. The circuit in the flooded rooms was still live when I returned a few days later, but soon died as a result of salt water corrosion. Fortunately, there was no fire and no one was electrocuted, but it was important to prevent this situation in the future

We studied FEMA’s guidance to elevate all electrical receptacles and switches, but here, too, we made our own modifications. FEMA suggests that all electrical connections be elevated above the BFE. This might be OK for the switches – that would sort of look normal, but for the electrical receptacles? Well, I was not happy about having all those plugs hanging down from an outlet in the middle of the wall, so we had to come up with another solution.

Our electrician’s idea was to integrate ground fault circuit interrupters, called a GFCI or GFI, into all the receptacles in the historic section below the BFE. The GFI is an inexpensive electrical device that will cut off the circuit immediately in the presence of water, such as a flood, thus preventing danger of severe electrical shocks or fire. These are routinely installed in kitchen outlets near a sink. All outlets in the historic section were fitted with GFIs, enabling all the circuits to shut down in the event of flooding.This solution will prevent electric shock and fires from live electrical connections after flooding.

The one caveat for coastal areas: salty water corrodes metal connections. If the connections were inundated, the ends will have to be cut once they dry out and new wire spliced onto the end before turning on the electricity again.

More, More Ventilation!

The last spot where we needed to find a venting solution was the living room closet and small space under the stairs – a tempting place to store lots of stuff, but very difficult place to clear out quickly, and hellish to clean up. It already had a louvered door which we could reinstall on the new framing, but we needed an outlet for internal air circulation at the other end of the space. We had allowed for a 10" venting slot between the closet and the space under the stairs. 
Closet venting slot (at right rear) to allow
circulation to the understair.

Joel’s solution was lattice work made from mahogany flooring scraps, which he installed under the stringer. Air now flows easily between the louvered closet door and the lattice through the slot at the back of the closet. 

Lattice at understair for ventilation.

This should work, but now I have to be disciplined about how much “stuff” I put in the closet!

Finally, “Floodproofing” the Furnishings

The only furniture lost to the storm were the brand new upholstered, and incredibly heavy, twin couches in the living room, the old wall-to-wall carpeting in the living room, and the large sea grass rug in the dining room. I couldn’t manage to move any of them before I evacuated. I couldn’t move the dining room table, either, but it was not very expensive, and I thought it was expendable. All the rest of the furnishings – tables, rugs, chairs, books, TV set and cable box, lamps - I either took upstairs or put in the elevated addition, like many experienced coastal denizens.

Except for tough furniture like the dining table, which survived the flooding unscathed, elevation seems the best solution for furnishings. This is fine for small things, like area rugs, lamps, small tables, etc. Chairs and sofas are something else again.

The living room in the doll-sized cottage can only fit two couches or a couch and a chair. These pieces of furniture are impossible for one person to move and cumbersome for two. The only solution I could see, therefore, was to “elevate in place.” I designed a system that uses 4 block-and-tackle assemblies – two for each couch – hooked to the ceiling that could lift the couch above the flood level. 

I needed to find a lightweight couch. That ruled out upholstered pieces, of course, but one with cushions would work. The solution: rattan, a lightweight, durable, natural material very familiar to Southeast Asia, where some 70% of the world’s supply is grown. And it's sustainable, if harvested appropriately.  Rattan is also experiencing an uptick in interior design popularity, so there are a fair number of suppliers and variety of styles. 

The rattan couches I found weigh less than 40 pounds each and can easily be lifted to the ceiling by one person using a block and tackle. The rest of the furnishings I will still have to move upstairs, but I figure it’s just a fact of life at the shore.

Couches elevated in preparation for flood event. 

Almost Done

By the weekend of the 1-year anniversary of Sandy, the new 2/2 insulated wood windows (an upgrade from ca. 1960 metal, non-functional, replacement windows) and fiberglass front door (no warping if wet), and wood trim were in place, the rooms were painted; the living floor and new mahogany stair and railing were done. Only the sanding and finishing of the floors and stairs remained to be done.

Completed living room after retrofitting.
It is wonderful being in my little house again, especially knowing that we have done everything possible to ensure that the trauma of the last 12 months would not be repeated and that the house would continue to contribute to the architectural history of Ocean City.

Not everyone will agree with the decisions I have made in this project, no doubt. They were the best solutions we could design, given the budget and the knowledge and experience we could draw on. Perhaps other people are even now thinking up better ways to address the issues we discuss here. I look forward to continuing this in historic preservation and hazard mitigation circles so we can arrive at innovative solutions that make our existing and historic buildings more resilient while they retain their historic character. 

Postscript: Next Steps – the Exterior

To complete the floodproofing of the house, one more step has to be done: the vinyl siding on the historic part of the house has to be removed. Not that I have anything against vinyl siding on new construction – in fact, the addition was clad in it. But the materials that make up the historic structure need to breathe. Currently, the pine clapboard is totally encased in vinyl – from the eves to some point below grade. This has caused severe deterioration of the sill, where the structure is closest to the damp soil and lacks a route by which moisture can evaporate.

Therefore, the next steps are already mapped out for us. The condition of the underlying wood siding is unknown at this point. With luck, it will only need minor repairs.

Stay tuned for the next chapter!


Below is a partial list of publications of particular interest to owners looking to retrofit older and historic buildings to mitigate flood damage:

Federal Emergency Management Agency:

FEMA has excellent resources available for download in the “FEMA Library.” To obtain a copy of these publications, see the section on Ordering Information.  They are also available to view and download from The order form is available at

Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood Hazard Areas in accordance with the National Flood Insurance Program. Technical Bulletin 2 / August 2008 (replaces TB 2-93). Provides guidance on the NFIP regulations concerning the required use of flood-damage resistant construction materials for building components located below the Base Flood Elevation in Special Flood Hazard Areas (both A and V zones).

Floodproofing Non-Residential Structures. FEMA 102, May 1986. This document provides technical information for building owners, designers and contractors on wet and dry floodproofing techniques.

Homeowner’s Guide to Retrofitting: Six Ways to Protect Your Home from Flooding. FEMA P-312, Third Edition (2014). The Federal Emergency Management Agency (FEMA) has prepared this guide specifically for homeowners who want to know how to protect their homes from flooding. This guide gives both clear information about the options available and straightforward guidance that will help make decisions, all in a form designed for readers who have little or no experience with flood protection methods or building construction techniques.  

Non-Residential Floodproofing -- Requirements and Certification for Buildings Located in Special Flood Hazard Areas in accordance with the National Flood Insurance Program, FEMA Technical Bulletin 3-93, FIA-TB-3. 4/93. Provides guidance on the NFIP regulations concerning watertight construction and the required certification for floodproofed non-residential buildings in Zones A, AE, A1- A30, AR, AO, and AH whose lowest floors are below the Base Flood Elevation.

National Flood Insurance Program (NFIP) Floodplain Management Bulletin: Historic Structures. FEMA P-467-2 / May 2008. The purpose of this floodplain management bulletin is to explain how the National Flood Insurance Program (NFIP) defines historic structure and how it gives relief to historic structures from NFIP floodplain management requirements (44 CFR §60.3). This bulletin also provides guidance on mitigation measures that can be taken to minimize the devastating effects of flooding to historic structures. omsearch&id=3282

Openings in Foundation Walls and Walls of Enclosures. FEMA Technical Bulletin-1. New Edition (August 2008). Provides guidance on the NFIP regulations concerning the requirement for openings in below-Base Flood Elevation foundation walls and walls of enclosures for buildings located in Zones A, AE, A1-A30, AR, AO, and AH. omsearch&id=1579

Protecting Building Utilities from Flood Damage, Principles and Practices for the Design and Construction of Flood Resistant Building Utility Systems. FEMA 348, November 1999. This document is to assist in the construction of buildings with building utility systems that are designed and built so that the buildings can be reoccupied and fully operational as soon as electricity and sewer and water are restored to the neighborhood. omsearch&id=1750

Protecting Building Utilities and Ductwork from Flood Damage. NFIP Technical Bulletin. Written for business owners, building industry professionals, floodplain managers State, Local and Tribal Representatives, Contractors and Vendors in connection with the Community Rating System (CRS) of the National Flood Insurance Program. omsearch&id=4609 

Recommended Residential Construction for Coastal Areas, Building on Strong and Safe Foundations. FEMA P-550, Second Edition / December 2009. This manual provides recommended designs and guidance for rebuilding homes destroyed by hurricanes in coastal areas and also provides guidance in designing and building less vulnerable new homes that reduce the risk to life and property. omsearch&id=1853

Selecting Appropriate Mitigation for Floodprone Structures. FEMA 551/ March 2008. This manual is intended to provide guidance to community officials for
developing mitigation projects that reduce or eliminate identified risks for floodprone structures. omsearch&id=2737

Wet Floodproofing Requirements for Structures Located in Special Flood Hazard Areas in accordance with the National Flood Insurance Program. Technical Bulletin 7-93, FIA-TB-7 12/93. This bulletin describes planning, design, and construction requirements for wet floodproofing certain types of structures and their uses under the National Flood Insurance Program (NFIP). The basic characteristic that distinguishes wet floodproofing from dry floodproofing is the internal flooding of a structure as opposed to providing essentially watertight protection. omsearch&id=1720

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