Re-roofing will create temporary inconveniences during or after the process has been completed. Thankfully, many of these issues can be mitigated or reduced. Let’s examine some typical problems and see how best to deal with them.
One of the most common complaints is the odours that arise during the application of asphalt on roofing. One remedy is to move the source of the fumes away from the building. This involves moving the asphalt kettle so that fumes are blown away from the building. A second option is to seal off air intakes near the point of application. The building can also be slightly pressurized. These steps are needed only when the roof is actually being applied. It is usually not necessary to be worried about air intake during tear off or when metal work is being applied.
To further alleviate odour concerns, it is recommended that you seal the top floor elevators. This will reduce the “piston effect” of elevators spreading odours through the building as cabs move up and down. If fumes remain a problem, supplemental mechanical ventilation and air cleaning machines can be rented to eliminate most odours. If concerns about odours are very high, fume-recovery systems are available for tankers and kettles. Be aware, however, that many roofers do not possess this technology, so fume recovery comes at a premium. If odour is the highest priority of all, use of a mechanically fastened single-ply roof with heat-welded seams will eliminate almost all fume-generating materials.
Another complaint with re-roofing is noise. Tear off is the noisiest part of the process; some noise may also occur during installation. Unfortunately, not much can be done to mitigate noise; however, roofers usually begin the tear off phase as early in the day as possible so most tear off is done before the majority of occupants arrive. Requiring rolls to be placed rather than dropped will reduce installation noise.
When noise is a major concern, there are two approaches to consider. If possible, eliminate mechanically fastened roof systems to avoid the noise of drills and hammers. This may not be possible unless the deck is structural or precast concrete. All other deck systems may require mechanical fastening to anchor insulation and base sheets.
A second approach, if conditions are appropriate, is to design a roof re-cover which will eliminate most of the tear off. Re-covers should be designed with caution as there are other factors — including wet materials, code violations and roof longevity — that need to be factored in. If you are considering a roof re-cover, and you are not experienced in roof design, commission a qualified roof consulting architect or engineer to evaluate existing conditions and determine if a re-cover is desirable or even feasible.
Unless an agreement is made up front to repaint walls and repair floor finishes, require that all travel ways be covered —including floors, walls and corners. Do not allow debris to be removed through the building. One option is to photograph all interior travel ways, landscaping and exterior walls before roof construction begins. These are compared to a similar set taken after the project. Any damage is immediately apparent.
Be sure to identify where sprinkler and other underground pipes are located if the contractor is going to bring trucks or dumpsters close to the building. This helps to avoid damage to the pipes and subsequent soil erosion, and repair costs associated with it. Be sure your consultant includes all such requirements as a part of the job conditions in the specifications. If job conditions are not put in the specifications, get another consultant.
If you experience a leak after that roof has been completed, seek an independent third party to look at the roof. Chances are, it wasn’t the roof that was leaking. To avoid recurring leak problems, have the roof thoroughly analyzed before you begin a roofing project. Have a knowledgeable consulting architect or engineer find the cause of the leakage. A leak may actually be caused by masonry cracks, loose coping stones, window sealants or other wall- and glazing-related problems, so there may be no need to re-roof.
Another common problem is when the project falls behind schedule. This can mean problems with tenant build-outs, school schedules, etc. To avoid this problem pre-project planning is required. Long before you anticipate re-roofing a building, have a consultant survey the roof condition and give you a professional opinion of how long the existing roof is likely to last. Get a reasonable estimate of the time that will be needed to complete the work, depending on the season in which the work is to be done. With this information, you can plan the re-roofing for the optimum time. This doesn’t mean that there will not be delays, but at least you will have placed the project at the time when it will cause the least inconvenience.
The final issue that can arise after install is surface failure. it begins to blister, split, crack, leak, etc. These usually mean the installation was faulty or the roof was not properly designed. The best prevention is a good set of plans and specifications developed for the roof and an independent third party watching installation. Expectations should be spelled out in detailed design documents, containing roof plan(s), specifications for installation and details of all conditions to be flashed. Contractors are much more conscientious when someone is monitoring their work. Hidden conditions or unforeseeable circumstances can be properly and expeditiously resolved when someone is on site. This also helps avoid the problem of a project running behind.
The worst category of roofing problems can legitimately be called disasters. Interior flooding is one example. This generally happens due to incomplete or damaged tie-ins between the old and new roof. Other floods can be traced back to a roofer being caught in a sudden rain shower. Other than encasing the interior in plastic until the project is complete, there are no guarantees that floods will not occur. However, the possibility of flooding can be mitigated.
Contractors want to remove and replace as much roofing as possible during the work day to increase their profitability. The tendency is to remove large areas of roof. The possibility of interior flooding can be reduced by requiring that the contractor tear off no more roof than can be replaced before the end of the work day. In case of uncertain weather, no more than can be replaced before wet weather arrives. Also, require that tie-ins be inspected prior to leaving the roof for the day.
If roofing is over a mission-critical area, the best way to minimize the possibility of floods is to design a re-cover roof. Once again, this should only be done if the conditions are appropriate for a re-cover and the building code will allow it.
The Worst Case
The worst case scenario in a roof project is catastrophic structural collapse. Collapses can happen in any climate and in any locale. A collapse is the result of overloading the structural capacity of the building. Common causes are installation of a heavily weighted roof on a building that was not designed for the system, inadequate drainage and lack of proper emergency overflows.
In the first case, the culprit is usually where a ballasted system is installed without the structural system being analyzed for load-bearing capacity. Installing a membrane system over a structural standing seam metal roof can be equally disastrous. Metal buildings are usually engineered to hold only the weight of the standing seam metal. Additional load can exceed building structural capacity. Defects in connections or fabrication of the structure increase the risk of failure. If the structural standing seam metal panels are not to be replaced with the same system, the new roof must be designed extremely carefully. They may use a very lightweight roof system such as sprayed-in-place coated polyurethane foam or a single-ply membrane over a lightweight insulation board such as a polystyrene.
Lack of drainage is another serious problem. In one case, an owner requested that the interior gutter be eliminated and replaced by drainage though exterior walls. The design added three emergency overflow scuppers for each drainage scupper installed in the parapet walls. The building collapsed following a storm. The reason: The contractor had convinced the owner that the overflows weren’t needed and that it would be cheaper to leave them out. So instead of water being dispersed through four locations, reaching a maximum depth of four inches, water built up to almost eight inches in the one drain location. The beam supporting the roof there collapsed, taking a quarter of the building with it.
Excessive water may also stem from something as simple as the contractor flashing over existing overflow scuppers. Drifting snow and ice can cover emergency overflows and block drainage. Overflows may simply be poorly designed. A common mistake in emergency overflows is to have both the primary drainage and the overflow tied to the same rain water leader, regardless of code strictures to the contrary. There may not be sufficient slope to the roof or sufficient drain capacity. Drains may be located poorly or in high spots.
The best way to avoid a structural collapse is to be certain that the person designing the roof is knowledgeable and that the design is followed. If changes are made to the design, be sure to keep the designer informed so that the contractor does not make critical errors.
Better Safe Than Sorry
Roofing problems often result from a low-bid approach. The condition of the roof and building and the owner’s specific requirements need to be studied to determine the best solution. Comprehensive construction documents should anticipate problems and provide either solutions or ways to avoid them. Competent contractors should be retained. An on-site project representative should be commissioned to observe the installation and help to quickly resolve any problems.
Renoteck has extensive experience re-roofing commercial and residential buildings in Alberta. They have a network of people that ensure the job is done properly. If you have a roofing project coming up give Renoteck a call!