Concrete Spalling Behind Siding

Spalling is break away of concrete surface which often extends to the top layers of reinforcing steel.

Concrete spalling behind siding.

Spalls can appear because the rebar has been exposed and humidity and water have begun to rust the rebar or because the concrete joints were improperly built. Spalling that occurs in a concrete driveway or sidewalk typically happens because the weather changed during the hardening process or something else occurred to prevent the concrete from finishing its curing. While spalling can occur on concrete it s especially a concern on stone brick or block where portions of the assembly can degrade to a point where they crumble. James hardie recommends that a slip sheet joint flashing is installed behind each butt joint in the siding.

Contrary to popular belief concrete is porous. The siding on this gothic revival style home looks like wood clapboard but it s actually fiber cement painted a custom color. Contractors might make the mistake of adding too much water but frankly most don t make mixing errors. The wood that goes under residential siding exterior sheathing performs several functions.

Without both of these elements the steel bar does not rust. Spalling of concrete affects a broad variety of structures including framed buildings multi storey car parks bridges jetties tanks and bunds. It also provides a. Spalling also can be caused by freeze thaw cycles in concrete and masonry products that have a high moisture content.

It adds insulation waterproofing and structural support for the framing. Rusting of the embedded steel reinforcing occurs when that reinforcing bar is exposed to water and air. This is a 6 wide piece of weather resistive material to make sure that no water gets through. Over the course of a winter or over the course of years as the internal pressure rises and falls it stresses the surface layer of the concrete which leads to spalling.

Spalls may be 150 mm or more in diameter and 25mm or more in depth and the occurrence of smaller spalls also possible as per aci 302 1r 4. 7 inch wide smooth lap siding primed about 1 50 per square foot picking the right siding for your house is a delicate balancing act between good looks durability maintenance and affordability. Most contractors will remember to do this but some of them try to save a buck by cutting squares of building paper for. Before that dries mix three parts fine sand and one part portland cement in your wheelbarrow with enough water to make the mix the consistency of thick oatmeal.

Mix one part type 1 portland cement and one part fine sand by volume. Hydrostatic pressure is not the only cause of spalling.