11-11241 - Laserfiche WebLink

Browse Search

. II � Investigate existing leakage conditions thoroughly. Before the installation begins, be sure that a thorough investigation of existing roof conditions has been performed, and that a review or "as-built" plans and specifications for the building as well as the assessment of current conditions has determined that the building is structurally sound and otherwise suitable for reroofing. -— It is helpful to know such details as the natu`re, extent, and duration of leaks that may have occurred through the old roofing. Because leaks often occur from sources such as building parapets, walls, and �_ windows, a new roof may not solve all leakage problems. Check the building walls for dampness, spalling brick, large stress cracks, and efflorescence (salty, powdery deterioration) - signs of problems that extend beyond the roof itself. Look for stains inside the building, and be sure that all sources of �_ ° such stains are known. Evaluate existing roof conditions: The cause(s) of poor drainage conditions should be thoroughly ! understood and solved as part of the reroofing process. For example, check for signs of ponding, a sure sign of poor drainage. If ponding occurs, determine the extent and duration of ponding. If needed, are overflow scuppers or other means of drainage present? Determine if a provision should be made � for their installation. Are there noticeable splits in the existing roofing? Splits may indicate a change in substrate or in metal ',L � deck direction; they could be indications that an expansion joint is required. Be sure that you know ALL types and conditions of substrate that are present, the spacing of structural � members under the deck, the direction and gauge of a steel deck, the thickness of concrete of '- insulating fill, drain placement, slope, and tbe location of expansion joints. Make a roof drawing: Once on the roof, work up a detailed roof drawing on the Mule-Hide Pre-Job � �` Survey showing all dimensions, drains, mechanical equipment, penetrations, skylights, monitors, parapet walls, and other features. You will have to submit your drawing(s) as part of the Warranty I Application. � °" Removal (tear-off) of existing roofing: Your crews should remove no more roofing and insulation from - a given area of the roof than can be completely covered with new insulation and Mule-Hide membrane _ that day. On tear-offs, ALL gravel and debr.is will have to be broomed from the deck. Reroofing over existing roofing: When reroofing over old roofing, broom ALL gravel and debris from the _ old roofing surface, cut out blisters and fishmouths, and seal. Remove and replace wet insulation as �� required. As general practice, prepare the entire roof before starting the Mule-Hide installation in order a to minimize contamination and insure the integrity of seams. �� Laying Insulation � If old insulation is present and is to be retained, you should determine if it is wet. The surest diagnostic - technique is by taking and evaluating a series of roof cuts. Alternatively, three techniques currently available to make this determination by indirect means are: nuclear moisture detection, infrared thermography, and electrical capacitance. - These techniques provide measurements of factors that can be associated with the presence of — moisture. As such, they can help point out certain inconsistencies in the existing roof system (and the - operator), but do not necessarily provide valid measures of moisture. Limited direct verification is always advisable. Whatever your method of investigation, wet insulation must be removed and replaced. The presence of wet insulation must be noted on the Pre-Job Survey. These areas must be designated on the roof �- diagram. _ Insulation must be laid and fastened according to its manufacturer's specifications, and at a minimum �