![]() The following description pertains to brick chimneys. The water control layer of a chimney is most commonly the brick layer or other exterior cladding comprising the structural enclosure supporting the chimney flue. This underlayment water control layer needs to be connected to the water control layer of the chimney. In high wind zones, a fully adhered roof membrane underlayment should be installed over the roof deck sheathing. The fundamental principle of waterproofing the connection between the roof assembly and the chimney is to connect the water control layer of the roof assembly to the water control layer of the chimney. Waterproofing of the connection between the roof assembly and the chimney is also important for controlling rainwater entry during high wind events such as hurricanes. More guidance is provided on the Retrofit tab. See the IBHS Fortified Home Hurricane Standards (2019) for additional details. IBHS requires that if the chimney is more than 5 feet above the roof, support detailing must be specified by an engineer or licensed design professional. See the CAD tab of this guide for a detail from IBHS that specifies a retrofit method for providing adequate anchorage of an existing chimney to the roof members. In its Fortified Home program, the Insurance Institute for Building and Home Safety (IBHS) requires that the chimney be adequately connected to the roof framing to prevent the chimney from collapsing or breaking away during high winds. Waterproofing of the joint between the roof assembly and the chimney is significant in controlling rainwater entry during high wind events such as hurricanes. For these reasons, the chimney must be properly anchored. These forces can be further increased when the chimney is located near the roof eave or rake edge. Not only will the collapse of a chimney damage the structural integrity of the roof and home, but they pose a significant risk of injury for occupants ( FEMA P-530, 2020). ![]() Chimneys, especially tall, narrow chimneys or those made of brick or stone that protrude high above the roof, are at an increased risk of damage and are prone to collapse under seismic forces. This tends to expose the chimney surfaces to higher wind pressure differences than those acting on the field of the roof assembly. It is common for chimneys to significantly extend or protrude above roof surfaces in order to provide sufficient “draft” for the venting of products of combustion. The guidance is applicable to both new construction and the re-roofing of existing roof assemblies. In addition, this guide also covers construction guidelines for chimneys built on homes in earthquake zones. ![]() ![]() This guide provides guidance on securing and waterproofing chimneys to resist toppling rainwater entry during high wind events such as hurricanes. Chimneys must also be waterproofed to resist rainwater entry during high wind events such as hurricanes. They must be adequately connected to the roof structure to resist wind and seismic loads based on site design wind speed and exposure category. Chimneys typically have numerous requirements beyond that of venting products of combustion. If you require a non standard bespoke design, we would be pleased to discuss with you the options available to reproduce a design sympathetically whilst always bearing in mind weight and cost limitations.ĭrawings of standard fixing details are included as part of the design service, along with a fixing kit including the lead mastic, clips, fixing bolts and washers.Īll our chimneys include the brit-lite flashing channel which ensures a simple and extremely effective flashing detail to ensure the stack remains water tight at all times.One of the largest penetrations in a residential roof assembly is a chimney. The chimneys are available for the following roof designs: mid ridge, gable end, mono pitch and flat roofs. Stone - natural and reconstituted stone stacks have successfully been reproduced in a similar format to the brick stacks. Render - the GRP waterproof box can either be pre-finished in a render type product or simply left with an expimet finish for site to render and match the exact colour and texture. Our replica chimneys are available in three finishes:īrick - bricks are cut into thin slips and corners to exactly reproduce the colour and texture on the stack of the main brickwork. Our prefabricated lightweight chimneys have been developed to satisfy the growing demand for planning authorities insisting on a return to traditional appearance of roof lines and developers looking to produce the aesthetics without having to radically change either the roof design or the footprint of the house type to incorporate any additional masonry or steel support. ![]()
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