Panelized wood roof systems are typically built using structural wood panels attached to a combination of wood sub-purlins, and these purlins attached to a wood framing member. Its convenience and rapid construction process have been an advantage of this process when compared with other roof systems. However, panelized wood roof systems typically leave some air pockets that will be converted into moisture pockets affecting your wood components.
Moisture Sources
Either during construction or occupancy moisture will affect adversely the performance of the panelized wood roof system. Below you will find the most common sources of how moisture can get into the roof system:- Using unseasoned solid sawn lumber
- Walls and slabs components that are still releasing moisture related to the curing process
- Poor soil or area drainage
- Roof leaks
- Permeability of the building components next to the panelized roof system
- Natural environmental humidity
- Moisture produced by HVAC systems
Reducing the Moisture of Panelized Roofing
Once that we can identify the source of the moisture affecting the panelized wood roof systems, it can be worked out to reduce its consequences. Here we present some tips that will help you reduce the moisture of your roofing system.
- Install your roof with a positive slope
- Use glulam or dry framing (grade stamped S-DRY) components
- Find moisture traps and ventilate them by cutting batt insulation by ½ inch
- If a concrete slab is used, install a vapor barrier to reduce moisture inflow
- If natural conditions produce a high moisture or humid environment, use preservative treated wood
- Protect the wood roof system by installing the proper roofing system as soon as possible.
- Provide outdoor air inflow until moisture content is below 18%.
- Proper job-site handling and protection must be assured to minimize the exposure of wood to humid conditions.
- If mechanical ventilation has been designed, it must be working properly.
- Maintain stable indoor air quality using dehumidifiers, air conditioning or any other mechanical equipment
- Avoid nails, screws, or other mechanical fasteners protruding above the surface of the roof deck.
- Do not install fire sprinkler systems in between the insulating material and the panelized wood roof system
- Use moisture retardant wood sealers
