Roof 6: Roof Framing Answers

I want to re-roof/shingle my house. I think there are three composite layers on there now and the house is a single level 1500 sq ft rectangle when viewed from the top, not a very complicated looking job.

Re-shingling a roof is not that hard, but with three layers on it now you have to remove everything right down to the sheathing. A roof is designed to hold no more than 3 layers of shingles on it. Most shingles weigh about 210 to 250 pounds per square (a square is 100 square feet: 10' x 10'), so you can see why the 3 layer rule.

Make sure you tie yourself off to the ridge of the roof if it is a steep pitch, by using a good sized eye screw or plate for that purpose.

Start at the ridge of the roof and take off the caps and then continue down the roof removing the shingles. A garden spade works well. They make a roofers tool for removing shingles with a wedge under the spade to help lift the shingles off, making it easier.

When the shingles are all off, go over the entire roof deck and nail in any loose nails and pull out any sticking up, there will be alot of them. Don't just hammer them over. Either nail them in all the way or pull them out, completely.

Next, around the eaves of the roof install a 50 pound roofing felt that is non-perforated. This prevents any ice from backing up the roof and water going through.

Then cover the entire roof deck that is left with a 15 pound non-perforated roofing felt, overlapping the joints by at least 4".

Start at the eaves with your shingles. Depending on which type you are installing, there is a starter row to put on first. This protects the joints above it from water leaking in. Don't depend on the 50 pound roofing for this. Then continue up the roof.

Every bundle of shingles I've put on always had instructions including drawings on the installation. Exposure, nails, etc. So take a few moments to read the instructions from the manufacturer.

For the ridge and hip caps, I use the same color of shingle but in a butt style shingle. These come in 3 tabs per shingle. With a utility knife, cut the 3 tabs off and bend them over the ridge with an exposure given on the bundle.

Overhang the 50 lb. roofing felt and shingles about 1 1/2" at the eaves and about 1" at the gable. Don't overhang the 15 lb felt, keep it flush with the barge board, just overhang the shingles themselves.

When installing barge rafters to support an overhang on a roof, using 2X6's, is there a standard (or recommended) spacing on how far apart to set the barge rafters? My overhang is 32", it's a 10 in 12 roof with a span of 17' plus the overhang. My rafters are on 16" centers and I'm going in three rafters due to the long overhang.

When framing for a gable end overhang, usually an overhang up to 16" can be done without building "ladders" or "look outs", as we call them, for the overhang. In your situation, with a 32" overhang you should use the ladder technigue as you have chosen. The rafters going out 90 degrees with the gable end usually sit on the gable end truss which is cut down by 3 1/2". The look outs then are 2x4 on edge and usually go inboard over the gable end truss into the next truss laid out on 24" centers. In your case with 2x6 rafters, I would do the same, except as you say remove one rafter from the gable end and attach the lookouts into the second rafter over from the wall line, at least 24" from the wall line.

On the wall line build your gable end rafter lower by 5 1/2" (or 3 1/2" would do, too depending on the choice of barge boards matching the fascia). These look outs should be laid out on 24" centers starting from the eave where your sheet of plywood starts. May as well have the 4' joint of the plywood butt up on one of the lookouts. Also, the ridge board should continue and catch the overhang rafter on the top and the rafter trim catch the bottom. When installing the plywood, try to get most of the sheet on the roof to help support the overhang. Stagger the sheets here by only 16" with the longest sheet in the center of the span. That is to make sure the overhang sheet nails into a rafter at least one inboard from the lookout connection. This way, your sheathing helps support the overhang, too.

Here is a drawing to help explain. This can apply to rafters, as well:

How do you determine the amount of shingles you need to cover a roof?

Measure the roof surface carefully. Each 100 square feet is called a square. There are usually 3 or 4 bundles in a square. Ask your supplier how many bundles in a square of your choice of shingle or give him the square footage and he will tell you. Also measure the eaves of the roof, the part that has the gutter attached. This gives the lineal feet of starter shingle and eave protection, usually of 50 pound, non-perforated roofing felt. Also measure the ridge and hips for shingle caps. Finally measure the valleys for valley flashing. It is a good idea to replace chimney flashings that go on the roof, other flashings and roof vents, as well.

Dave