construction Construction is a general term meaning the art and science to form Physical object, objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Pr ...

, capping or window capping (window cladding, window wrapping) refers to the application of aluminum or vinyl sheeting cut and formed with a brake to fit over the exterior, wood trim of a building. The aluminum is intended to make aging trim with peeling paint look better, reduce future paint maintenance, and provide a weather-proof layer to control the infiltration of water.Gibson, Greg. ''Remodel!: an architect's advice on home renovation''. New York: J. Wiley, 1996. 269. Print.

Overview

The capping application must direct water away from the original under-lying wood material and prevent infiltration of water into the structure. Cladding applied to exterior window and door casing (brick-moulding) and their associated parts is often referred to as ''window capping'' or ''window cladding''. This sort of capping is typically applied in order to eliminate the need to re-paint wood window trim. The

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

capping helps to prevent wood rot by protecting the wood from water and snow. However, capping will exacerbate wood rot if the moisture in the wood is coming from inside the building or the capping leaks. Good installation of capping allows for an outlet for water in the event of a leak.

Caulking Caulk or, less frequently, caulking is a material used to seal joints or seams against leakage in various structures and piping. The oldest form of caulk consisted of fibrous materials driven into the wedge-shaped seams between boards on ...

and

sealant Sealant is a substance used to block the passage of fluids through openings in materials, a type of mechanical seal. In building construction ''sealant'' is sometimes synonymous with '' caulking'' and also serve the purposes of blocking dust, so ...

materials may be used to help prevent leaks but these products are not considered reliable in the long-term. A sill that has been clad should provide a "drip cap" or "drip-control" function. This will serve to direct water away from the wall surface directly underneath the sill. The leading edge of the sill must be the lowest point on the sill to ensure that water does not wick into the sill material. Window capping may provide a marginal increase in

energy efficiency Energy efficiency may refer to: * Energy efficiency (physics), the ratio between the useful output and input of an energy conversion process ** Electrical efficiency, useful power output per electrical power consumed ** Mechanical efficiency, a ra ...

by decreasing the potential for drafts by providing an extra barrier between the exterior and the interior. The most common material used in residential window capping is factory painted aluminum. An alternative to factory painted aluminum is to use a vinyl coated aluminium material. Aluminum capping can be painted so long as the painter is highly skilled and knowledgeable in the field of metal painting.

Criticisms

Capping can hide problems rather than fix them. Aluminum and vinyl are impermeable materials so the natural transfer of moisture through the wood trim will be trapped when it reaches the capping material. The quality of paint on some aluminum coil stock begins to chalk or fade in about five years so the claim of being maintenance free can be misleading.

References

{{reflist Building engineering