Michigan State University Extension
Home Maintenance And Repair - 01500014
06/24/03
Drying Walls After A Flood
Inner Walls
Walls must dry from the inside out. The interior
framing of walls should be allowed to dry thoroughly.
Sometimes this process takes weeks or even months. To
release water and mud from walls remove top and bottom
strips of siding on the outside of the building. Drill
several holes in walls near the inside floor line.
The total drying time will depend partially on the
amount of dry air that can circulate through the studding
(called "chimney action"). To provide for maximum chimney
action, first consider the construction of the building.
Fire Stops or Cross Bracing
These are horizontal or diagonal braces between the
vertical supports or studs.
Cross bracing will prevent chimney action between
the studding. However, cross bracing is not usually found
in modern construction, except in two-story houses where
is has been specified. To allow free air movement, remove
interior or exterior wall covering wherever cross braces
are located. To check for cross bracing or fire stops,
extend a stiff wire into the wall cavity.
Insulation
Any types of insulation will be ruined if water-
soaked. You will probably have to replace flood-soaked
insulation.
1. Loose fill (such as vermiculite) will settle to the
bottom of walls. As it dries it can be removed. If not
removed, loose fill insulation will create odors and
eventually cause decay of the studding.
2. Rock wool batting insulation will also bunch and
settle. If it is absorbent it will create odors and could
eventually cause studding decay.
3. Fiberglass batting will also bunch, but will not
develop odors. Its insulating value will be greatly
reduced.
4. Reflective surfaces (such as aluminum foil) will
probably lose their reflective ability thus decreasing
their insulating effectiveness. The material itself
should be undamaged.
Wall Coverings and Finishes
1. Plaster will take weeks or even months to dry but may
not be ruined by water. Old plaster, however, may
disintegrate after being wet for a long time.
2. Dry wall (plaster board) will warp and disintegrate in
water. Warping above the water level can also be
expected. Drywall that has been submerged must be
replaced.
3. Laminated paneling (plywood, masonite) will separate
and warp above and below the water level. The extent of
damage will depend on how long the paneling was
submerged, and how quickly moisture is removed from the
studding. Slow drying decreases the possibility of
delamination.
Siding
1. Masonry will dry slowly but will be undamaged
except for possible cracking or settling. Open inside
walls to prevent mildew and decay of wooden supports.
2. Lapped siding (wood, asbestos, aluminum). Remove
strips or sections to dry insulation and studding. The
type of sheathing will determine drying rate. To prevent
oxidation, make sure backing of aluminum siding is dry.
Sheathing (material between studding and finish siding)
1. Wooden boards will dry slowly and some will warp.
If possible, renail warped areas before they dry. Replace
those that are too badly warped to salvage.
2. Sheathing board is usually absorbent and will be
difficult to dry. Some will disintegrate or separate and
must be replaced.
3. Plywood will probably separate in places and must
be replaced. Marine plywood will not warp or separate,
but is generally considered too expensive to use in
residential construction unless the building is subjected
to frequent flooding.
This article was written by Anne Field, Extension
Specialist, Emeritus, with reference from the USDA
Disaster Handbook.
This information is for educational purposes only. References
to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not
mentioned. This information becomes public property upon
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Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in
cooperation with the U.S. Department of Agriculture. Thomas G. Coon, Director,
MSU Extension, East Lansing,MI 48824. This information is for educational
purposes only. Reference to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not mentioned.
This file was generated from data base 02 on 02/04/08.
Data base 02 was last revised on 06/24/03.
For more information about this data base or its contents please contact
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