dwestmc
01-03-2009, 05:19 PM
My company had to reproduce an exposed rafter detail last year on a house we built and we had a similar quandry. This link will show the pics http://imageevent.com/meadowview/jobphotos/exposedraftertails We wanted to mimic the look of the old house rafter tails but without the problems. It was a challenge to figure out the right materials and methods because there were so many options. Although I have seen many homes locally that have simply extended the ends of the KD rafters and made the decorative cuts on them, I was not too keen on using KD lumber in a coastal environment on such a beautiful home that will be expected to last 100 years. As we sorted through our options we narrowed it down to red cedar, Douglas fir, cypress and red Meranti (in the mahogany family but technically not mahogany). We ran some linear foot prices and by the time the material was purchased and milled down, Meranti was the least expensive, but the key factor was that it is available in stock at 1-3/4" x 10" thickness from our local supplier. We liked the beefier look of the 1-3/4” as opposed to the 1-1/2” thick cedar, fir or cypress. Having used Meranti for many decks we determined that with proper priming, painting and the fact that it is up under cover of the roof, we ought to be good. Because the meranti tends to bleed we needed to use a good exterior stain-blocking primer and a high quality exterior paint.
After the mountain of 2x10's arrived we got our work area set up and built all of our jigs and templates. The straight cuts were cut using a combination of several chop saws set at certain angles and 2 circular saws. All the rafter tail points needed to have a 1” radius round over so we rough cut them with a jigsaw and finished them off with a large router, hardboard template, and a solid carbide up-cut spiral bit. Every cut required a reasonable amount of precision since they would be painted prior to installation and could not be trimmed in place. Many test pieces were cut and fitted before we settled on a final pattern and since it was a hip roof with two different pitches, we needed no fewer than 5-6 different templates. Trying to keep ahead of the roof framers was a chore as it seemed as though as soon as we finished one batch they needed another. Keep in mind that after we cut and sanded each batch we had to set up a dry area where we could prime and paint them with 2 coats of finish and then set them in a drying rack. We had these things spread out all over the place. In all there were over 300 rafter tails, each about 5 feet long. Since the exposed length of each tail was about 24” we decided to bury 36” up into the roof for strength. This proved to be more than adequate.
Instead of laying out the KD rafters first and then sistering the tails, we used the tails for the primary lay-out and then shifted the KD rafters so they would be sistered. Bead board was chosen for the under side of the roof overhang and in order to minimize future maintenance we chose to use PVC bead board which was about ½” thick. We chose to drop the rafter tails by ½” below the main rafters so that the top of the bead board would end up being flush with the rafters. This would allow us to cover the PVC bead board with the usual 5/8” CDX sheathing because everything was in the same plane. The combined thickness of the sheathing and bead board was about 1-1/8” so the roofing nails did not pop through on the under side. We used 1” roofing nails for the first few feet around the eaves just to be safe.
The architect asked us to apply a 1x8 fascia notched into the tails and the bottom edge of the tails would have a radius cut on the point. The fascia was used so that the wood gutters had a good solid backer. The other option was to sit the gutter into the notch on each rafter tail which means that the notches would have to have been different on each tail because of the pitched gutters. This would have been a nightmare and would likely have meant that each tail would have to be cut in place-not an easy task 20 feet above the ground on staging. The hip rafters also needed a notch cut into them so this required both a left and right tilt circular saw that would tilt beyond 45 degrees. I think we used both Milwaukee and DeWalt opposite tilting saws which both tilted to 50 degrees. The Meranti hip rafters had to be notched to sit on top of the main LVL hip rafter since they could not be sistered like the common rafter tails.
The venting was also a consideration not to be taken lightly. We could not use standard soffit vents so we had to devise a clever frieze board detail. We installed a white strip vent RS-400 made by Cor-A-Vent http://www.cor-a-vent.com/raft-a-vent-rs-400.cfm
So it ended up flush with the under side of the PVC bead board. The color blended in well with the white trim color so it was not visible from the ground.
The installation of the tails took some time because the Meranti is quite hard and needed to be screwed in with impact drivers. Using string lines from hip to hip we set each tail in place and screwed them off. Once an entire section was in place we attached the pre-painted 1x8 fascia to lock everything in place. Since the tails were dropped ½” we had to raise the fascia to prevent the PVC or sheathing from showing on the edge. The galvanized drip edge covered up any variances.
All in all the process went very well but very time consuming to do a first rate job. This easily added a couple weeks of labor to the job. I think the time was well spent and will remind the owners for years to come what a nice house they have.
Please feel free to contact me with any questions
David West
Meadowview Construction
Best of Boston 2009
davewest@mvconstruction.com
www.mvconstruction.com
After the mountain of 2x10's arrived we got our work area set up and built all of our jigs and templates. The straight cuts were cut using a combination of several chop saws set at certain angles and 2 circular saws. All the rafter tail points needed to have a 1” radius round over so we rough cut them with a jigsaw and finished them off with a large router, hardboard template, and a solid carbide up-cut spiral bit. Every cut required a reasonable amount of precision since they would be painted prior to installation and could not be trimmed in place. Many test pieces were cut and fitted before we settled on a final pattern and since it was a hip roof with two different pitches, we needed no fewer than 5-6 different templates. Trying to keep ahead of the roof framers was a chore as it seemed as though as soon as we finished one batch they needed another. Keep in mind that after we cut and sanded each batch we had to set up a dry area where we could prime and paint them with 2 coats of finish and then set them in a drying rack. We had these things spread out all over the place. In all there were over 300 rafter tails, each about 5 feet long. Since the exposed length of each tail was about 24” we decided to bury 36” up into the roof for strength. This proved to be more than adequate.
Instead of laying out the KD rafters first and then sistering the tails, we used the tails for the primary lay-out and then shifted the KD rafters so they would be sistered. Bead board was chosen for the under side of the roof overhang and in order to minimize future maintenance we chose to use PVC bead board which was about ½” thick. We chose to drop the rafter tails by ½” below the main rafters so that the top of the bead board would end up being flush with the rafters. This would allow us to cover the PVC bead board with the usual 5/8” CDX sheathing because everything was in the same plane. The combined thickness of the sheathing and bead board was about 1-1/8” so the roofing nails did not pop through on the under side. We used 1” roofing nails for the first few feet around the eaves just to be safe.
The architect asked us to apply a 1x8 fascia notched into the tails and the bottom edge of the tails would have a radius cut on the point. The fascia was used so that the wood gutters had a good solid backer. The other option was to sit the gutter into the notch on each rafter tail which means that the notches would have to have been different on each tail because of the pitched gutters. This would have been a nightmare and would likely have meant that each tail would have to be cut in place-not an easy task 20 feet above the ground on staging. The hip rafters also needed a notch cut into them so this required both a left and right tilt circular saw that would tilt beyond 45 degrees. I think we used both Milwaukee and DeWalt opposite tilting saws which both tilted to 50 degrees. The Meranti hip rafters had to be notched to sit on top of the main LVL hip rafter since they could not be sistered like the common rafter tails.
The venting was also a consideration not to be taken lightly. We could not use standard soffit vents so we had to devise a clever frieze board detail. We installed a white strip vent RS-400 made by Cor-A-Vent http://www.cor-a-vent.com/raft-a-vent-rs-400.cfm
So it ended up flush with the under side of the PVC bead board. The color blended in well with the white trim color so it was not visible from the ground.
The installation of the tails took some time because the Meranti is quite hard and needed to be screwed in with impact drivers. Using string lines from hip to hip we set each tail in place and screwed them off. Once an entire section was in place we attached the pre-painted 1x8 fascia to lock everything in place. Since the tails were dropped ½” we had to raise the fascia to prevent the PVC or sheathing from showing on the edge. The galvanized drip edge covered up any variances.
All in all the process went very well but very time consuming to do a first rate job. This easily added a couple weeks of labor to the job. I think the time was well spent and will remind the owners for years to come what a nice house they have.
Please feel free to contact me with any questions
David West
Meadowview Construction
Best of Boston 2009
davewest@mvconstruction.com
www.mvconstruction.com