Table of Contents
How far apart should rafters be on a metal roof?
Roof trusses should be 24” apart, on center. Trusses are allowed to be closer together, at either 12” or 16” on center, but building codes allow for 24” on center spacing without using heavier duty fasteners for truss to wall connections.
Can you put metal roofing directly on rafters?
Metal roofing can be installed directly on open rafters. The vapor barrier built into such insulation helps to minimize the amount of condensation that drips down from the roof, and the insulation itself can help to keep the interior of the building at a comfortable temperature.
Do you need furring strips for metal roof?
When installing a metal roof over an existing roof, insulate the spaces between the wood strips with rigid insulation to prevent condensation before installing the roofing. You also need to add furring strips. Twenty-four inches is a common spacing of furring strips for a metal roof.
How far apart are purlins for metal roofing?
The purlin are ultimately used to fasten the roof steel providing a diaphragm effect, along with the siding, when properly engineered and installed. Spacing is typically 24″ on center in low snow loads and is reduced based upon truss span and snow load.
Do you need a vapor barrier under a metal roof?
To avoid condensation buildup with your metal roof, you will need to have a moisture barrier in place. It depends on air temperature, water vapor near the metal panels, the prevalence of warm air in and around your roof assembly, and other conditions.
Do you need to put strapping under metal roofing?
Single wood strapping is better than no strapping, as it creates a wider gap between the existing roof decking and the metal roof, but doesn’t afford enough ventilation to resolve condensation issues. It also does not allow leveling of the roof, which corrects swells and swales on the roof.
Do you have to put plywood under metal roof?
As long as the interior of your roof is protected from moisture accumulation, underlayment is not required, though homeowners planning to insulate their house heavily may choose to install plywood to protect their investment.
Can you put a metal roof over shingles without furring strips?
One option for installing a metal roof over shingles without furring strips is to use a cross-batten style. A cross-batten technique involves laying down vertical battens first. Next, the battens attach through the roof deck to your rafters.
Can I install metal roofing directly over shingles?
In almost every case, the answer is yes, you can lay down a new metal roof over an existing shingle roof. This is one of the many reasons metal roofs keep growing in popularity – their installation doesn’t require completely tearing off the existing roof, which is a time-consuming and expensive job.
Can metal studs be load bearing?
Heavier gauge metal studs are used in load bearing walls and structural applications such as exterior walls. Framing techniques for metal studs are similar to those of wood construction. Metal studs are available in many of the same basic dimensions as wood studs.
Can you use metal studs for roof?
Like many transitions in the building industry, the use of metal studs in exterior wall construction and roofing in new construction developed out of the twin concerns of value engineering and cost reduction.
Can you walk on a metal roof with purlins?
Metal roofing can be walked but, homeowners should refrain from doing so for safety reasons. If a contractor does need to walk your roof, they should practice sound safety procedures and follow OSHA safety requirements.
Can I use 1×4 for purlins?
Kiln-dried softwood is recommended for purlins or decking (pine, fir, hemlock, and spruce). On re-roofing projects where the condition of the old decking is in question, or where existing shingles will be left in place, new 2×4 or 1×4 purlins should be fastened through the decking and into the rafters.
How do you attach purlins to metal trusses?
ADDING PURLINS Metal zee purlins should overlap on top of a truss. They should be placed on the outside of the truss clip with the bottom leg of the zee pointing toward the sidewall of the structure. The outermost truss clip will need to be adjusted for a vertical alignment.
What is the screw pattern for metal roofing?
Lap screws are spaced 12” to 18” on center. The panel screws are spaced out so that every third corrugation has a screw including both sides of the panel sidelap. When the corrugated sheeting is 39” wide instead of 37” wide the screw placement will be slightly different as shown in the diagram below.
How much should a corrugated roof overlap?
An overlap of 150mm is often recommended for roofs with 10° pitches, whilst 300mm is recommended for 5° pitches. Always allow for an overhang of at least 60-70mm so that water can run off without coming into contact with rafters or purlins, which can lead to damp and structural weakness.
What underlayment do you use on a metal roof?
Known by many different names (including felt paper, roofing tar paper, and asphalt-soaked felt), felt underlayment is the most commonly used type of underlayment material on steep-slope metal roofs.
What is the best insulation to put under a metal roof?
Property owners choose fiberglass batts because: It’s one of the cheapest and easiest ways to insulate a metal roof. It’s versatile, meaning you can cut it according to your specific needs. You can also either have it placed under the metal roof panels or installed onto an existing roof’s surface.
What underlayment should be used under metal roofing?
While metal roofing needs high heat ice and water shield as underlayment, it’s also used with premium roof systems (slate and cedar shake) to add extra protection. However, it will be more expensive than the other types of underlayment and adds to the cost of your roof replacement.
