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6.1 JOINERY AND FITTINGS
The priority with measures contained in these guidelines is to improve protection of the building from damage to the structural (i.e. load bearing) components so that it can continue to be occupied safely without major reconstruction being necessary.
Protection of fixtures has not been a focus as:
• Components such as doors, skirtings and architraves are relatively low cost and can be easily replaced.
• Higher wear and tear items such as floor coverings and ovens/hotplates have a high depreciation and are actually replaced at least a couple of times over the life of a building.
• Built-in furniture such as kitchen cabinets and bathroom vanity units have a short service life compared with the house structure and are updated at least a couple of times throughout the life of the house.
Damage to such components would not prevent the reoccupancy of the house to the same degree that severe structural damage would.
6.1.1 Problems
Fixed joinery and built-in furniture are often flood damaged. They include:
Joinery
• skirting boards
• architraves around windows and doors
• doors and door jambs (internal and external)
• windows and window frames
• staircases or steps in two-storey or split-level houses.
Built-in furniture
• kitchen cabinets
• built-in wardrobes
• vanity units
• laundry cupboards
• shelving (e.g. pantry, linen press).
Built-in furniture items are often delivered as prefabricated units and installed in such a way that moisture traps are created under or behind them.
The adhesives and materials used in the manufacture of these items can also be a major problem when flooded. Certain materials are very susceptible to delamination and warping when immersed. It is quite common to use reconstituted timber products, such as particleboard, MDF and hardboard for many of these items.
6.1.2 Design Suggestions
It would be unrealistic to expect that damage to a majority of these items can be avoided cost effectively. In many cases, they should be removed to provide access to damaged walls or to assist drying. However, there are steps to reduce the impact of floodwater on or by these items. They should be detailed to avoid moisture traps, making sure that water drains from them and around them easily. Further, to ensure that the materials in these units and in the surrounding structure dry out quickly, good all round
ventilation is essential.
Key design and production issues:
• avoid false floors in cupboards and wardrobes,
• build units on legs to allow for cleaning and free flowing air underneath,
• provide holes for drainage and ventilation to closed-off areas and hollow components,
• construct joints so they shed water,
• avoid grooves and hollows that can collect water, and
• use supports at closer centres with hardboard and ply panelling to limit permanent distortion (position supports at less than 500mm centres).
Some items can be omitted altogether e.g. it is practical to omit skirting boards completely in houses built from “solid” walls such as double brick, concrete blockwork, precast concrete.
REDUCING VULNERABILITY OF BUILDINGS TO FLOOD DAMAGE
107 SECTION 6 NON-STRUCTURAL COMPONENT DESIGN Such construction also permits the use of steel door frames which require no architraves, (Figures 105).
Face brick or rendered brick without skirting boards can significantly reduce wall damage. Steel door frames will further reduce the repair costs.
Figure 105 Reducing timber skirtings and architraves
aspect that requires attention is the area behind the kickboard and under the bottom shelf. This is usually an inaccessible void space about 150mm deep between floor, wall and cupboard.
Floodwater and debris can enter this area and provision must be made to be able to clean and dry this space. One solution is to use a removable kickboard and support the base of kitchen cupboards off the floor on short metal or plastic legs, (Figure 106).
Built-in wardrobes that have full-height doors and a common floor surface with the room will avoid a boxed-in void at the bottom of the wardrobe.
Ceramic pedestal-type units or hand basins in benches with metal or plastic legs rather than vanity units will better resist flood damages. If metal legs are not fitted and a standard kickboard is used, it is advised to have this as a screw-fitted removable section to clean and dry under the unit. Wall-mounted units can provide alternative storage space.
6.1.3 Material Selection
GeneralWherever possible, materials that will have optimum performance in flood conditions should be used.
Longer-term immersion can affect and permanently damage timber-based products.
However, well designed and built timber products can be expected to survive moderate flooding. Whilst a number of factors will affect the performance (e.g. individual timber specimens, different standards of production and manufacturing, application), the following list ranks timber products from best to worst:
• solid timber,
• marine grade plywood,
• exterior grade plywood,
• hardboard and MDF, and
• particleboard.
Products built from well-sealed solid timber with moisture resistant adhesives perform the best in flood conditions. Moisture resistant adhesives must be used in all glued fabrications.
Traditional timber stairs can include enclosed areas which are difficult to clean and dry. A simpler approach is to have an open-tread solid timber stair. As a staircase may have to be used to move large furniture items quickly prior to a flood, the stairs should be wide and easily negotiated. It is recommended to have 1 metre clear between balustrades, or wall and balustrade and to have treads at least 280mm wide and risers of no more than 180mm high
(see Figure 47).
One difficulty with kitchen cabinets, vanities and wardrobes is that they are placed closely against the wall which restricts ventilation. Another
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If plywood is used, it should be exterior, or preferably marine, grade and all edges should be sealed. Thin ply veneers should be supported at closer centres than normal to restrict buckling.
Joinery Skirting boards
Skirting boards made from MDF can be unsatisfactory when exposed to water. Even when painted front and back, water can create problems at corner joints or where there are fixing nails or screws.
Solid timber skirting boards are generally less affected by water damage than MDF skirtings, but may distort.