two questions about reroofing

[imported_noel]

Hi all,
I'm almost ready to put shingles down on my roof. And I have a couple of questions.

First, this house probably doesn't have a straight line in it. I want to put the shingles down right, and not off at some wonky angle. I've tried to cut the overhangs with refference to the wall, but I don't know. Is there some way I can mark out a purpendicular (sp?) line to the ridge line, something I know is at a true right angle to the lenght of the house? I was thinking of marking out a top and bottom of a circle, but, i don't know.

The other thing is that on the ends of the (some) rafters, the wood has rotted. It varies with each rafter end (overhang). On some of the rafter ends it is just on the lower corner, some it is higher and goes back a inch or two. It is a black rot. I can't go and repalce all these rafters. Is this rot going to be a problem? Can I leave it as is and put new trim boards up? can a paint it with something? Will it continue to rot once it is in the dry?
Should I cut the overhangs back to 8"? It was only a 10" overhang to start with.

I'll be putting on a galv. metal drip edge, if that makes any difference.

Thanks.

[Wgoodrich]

True right angle I would say is not much of your true worry.

first you need to tell us what you have now. How many layers of roofing do your have. What is the pitch of this roof. 4/12 or 12/12 etc. then tell us if you have wood shank shingles under this roof.

The roof you are thinking of cutting off I am suspecting is the fly rafter and strongly suggest you repair it and leave that fly rafter on the house for both structural sealing integrity and for looks.

If you have a fly rafter that is saggin it should tell you that you have rot under the roof in that area.

If you have an over hang that is flying upward then 1/2 decking should level that rise out for you automatically.

You speak of rotting on your rafter tails. This suggests that you have let the roof go longer than should have been making us wish to look further into the roofing that exists concerning 1 by lathing or plywood sheathing.

The rafter tails you should strip off the decking above and cut off those rafter tails back to eliminate the rot. Then you should sister on new rafter tails to the existing rafters extending back out to where your gutter back will be installed. This is not expensive and really not that time consuming.

Do not short cut this roofing job or you will be doing it again at a much more expensive repair cost the second time.

Tell us how many layers of asphalt shingles and if with wood shank shingles under the asphalt. Be sure to answer accurately so you can properly prepare for you project ahead.

If you are reroofing more than a 8 / 12 pitch then be safe and use roof jacks as you work.

ONce you tell us the type roofing and how many layers and the pitch of the roof then we can more accurately get to the meat of your planning for this project.

Done right usually means done faster and less expensive with a more professional job when completed. Do not short cut on your roof if you want to be happy for the next 25 years.

HOpe this helps

Wg

[imported_noel]

ok, to start out with, I had to let the roof go for a few years. Didn't want to, but anyway. My house is a basic 6/12 roof with a gable at both ends. I had to replace three rafters on the back side of the house that were rotted and rebuild one half of the gable that covered the front porch, (rafters, ceiling joists, decking, etc). So, the shingles came off, the old board sheathing came off of the repair area. I have a new pylwood surface on both sides of one gable end. on the backside of that gable end, the new decking extends towards the other end of the house and goes back about half way, stagered like, and meets the old board decking. This covers the repair area where I replaced the 3 rafters. The old board decking is a little thicker than the plywood, so I was going to make a lap joint there where they meet with 30# tar paper. I didn't have any roof leaks on the rest of the backside.

I could think ot the term 'raftertails'. That is what has the rot on it. mostly on the lower part of the tail.

The rest of the shingles will be removed and new paper put down.
I'm probably going to go with a Tamko 30 year architectual shingle at about 36 bucks a square.

I have done this work myself, and pushing 4x8 sheets of plywood up a ladder and onto the roof, where it wants to slide right back off, is something I don't care to do any more of.

Thanks

[imported_noel]

Also, since I can't get this all done quickly, I've had to cover my work up with a tarp and plastic drop sheets. This has failed to keep all the water off my new work at times and I have some grayish/blackish water trails. I guess this is algae that formed while the wood was still wet. I do need to hit these gray streaks with something to remove this or kill it? Or is this water discoloration ok now that it is dry?

Thanks

[Wgoodrich]

If the water is deleted to the mold areas the mold will die and disappear. You might want to put a sealer on that mold if you are concerned with health risk of the dead mold till it dissapates.

If your rafters have 3/4 lathing called 1 x 6 board with a gap between each 1 x 6 board spanning across the rafters then you may use 3/8" plywood because the existing 1 x 6 would be your spanning support.

If your rafters have open spans between rafters and the decking is the spanning support then if you rafters are 16" on center spread then 1/2" or 5/8" exterior plywood is fine for the sheathing.

If you stack plywood on a 6 / 12 roof then nail a 2 x 4 on the decking and stack the plywood on that toe board 2x4 as you spread and nail your plywood sheathing on.

Black paper is requried all over the plywood decking before you install your shingles.

The plywood sheathing on the gable ends over hanging 16" is the support of that outside rafter called a fly rafter with the ridge board extended out to catch that fly rafter top of roof and bottom of the roof wall top plate.

It is fine to strip the roof to the rafters only in an area that you can cover in black paper that night to limit damage if it rains. Just be sure to strip your roof from the west side gable end to the east using metal roof edging over the ends of that black paper. This way weather coming if it storms will blow against the roof edge and not rip the paper off during the storm. Use scrap 2 x 4 or screen stock as temporary strips to help hold down the black paper until the shingles are installed.

Be sure to use a starter strip roofing shingle on the bottom of the roof to start you shingles.

Take your time and think ahead and you should be fine.

If you find after stripping your decking a single section of rotten or damaged rafter then sister a matching board on the side of that damaged rafter same as if you were extending your rafter tails on past the outside wall.

6/12 pitch only allows a maximum of two layers of shingles. Do not exceed that. Preferrable to strip the roofing and decking to get to any unseen rot or damage yet unknown.

When setting each shingle be sure not to use the rain gauge to position your shingle but instead match the top edge or the shingles. The rain guage slots on the bottom of the shingles are not manufactured the same on each shingle and will lead you to a crooked row of shingles if you use those rain slots to gauge setting your shingles.

Hope this helps

Wg

[Anonymous]

Two methods for establishing a true 90 degree line:

The old 3,4,5 method( The carpenters version of Pythagoras): Using the roof question as an example, snap a line parallel to the drip edge (check it against the ridge too), choose any point along this line, ( I use 1 foot up from the eave for the parallel line, 3 feet from the gable edge for the point on the line, as this is where the first full shingle will most likely be placed.) Measure from the point, along the line 3 feet or any multiple of 3 and make a mark. Measure from original point up the roof 4 feet or multiply times the same number you used for 3, don't just make a small mark this time, swing an arc.
Hold tape measure on 3 foot mark, measure toward 4 foot mark, swing an arc holding marker on 5 feet ( or multiple). The intersection of the two arcs forms a perfect 90 degree line from the original point.

Another method: On the line parallel to the drip, make a point.(point a) This can be anywhere on the line. Measure from this point along the line any distance, mark.(point b) Return to point a, measure the same distance in the other direction, mark.(point c)
From points b and c measure any equal distance up the roof, swing arcs. The intersection is 90 degrees from point a.
Sorry this got so long, and if it is over simplified or over complicated.

[Wgoodrich]

YOu provided a very educational point toward getting a square start with your shingles.

Thanks for your time, well said

Wg