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-   -   reroofing garage - a few questions (http://www.diychatroom.com/f9/reroofing-garage-few-questions-47553/)

wombosi 06-26-2009 06:41 PM

reroofing garage - a few questions
 
i have a really blown roof on the south face with substantial leaking around the chimney. i had previously slathered tar all over the flashing but it hasn't done anything. i've been planning on redoing ther wehole roof, and now i have the shingles.

what's on there is ONE layer of three tab shingles, with tar paper undernath, galvanized drip edge on the eaves only and not the rakes.

i've already repaired a rotten section of wall inside along the chimney, with new double top plate, bottom plate, and stud, as well as a sistered rafter.

the plan is to now shingle directly OVER what's on the roof n ow, without stripping anything. i will take out the old flashing and redo it.

the question is, should i strip the whole area around around the chimney, throw down some ice and water shield, then reshingle, or should i keep it really simple and just replace the flashing, slather around some tar, and shingle away?

also, i don't plan on adding drip edge up the rakes, since there is no evidence or rot there at all, and it's been that way a long time.

i guess the big question is how to approach the area around the chimney. also, i have a general idea how to do flashing, but haven't actually done it. could you guys point me to some literature, or walk me through it, please? i'll be using a big roll of aluminum.

thanks a lot,
ben

PS:
garage is roughly 1920s, with exposed t&g sheathing. everything looks bone dry and sound except for around the chimney (and the framing has been replaced). someone had previously patched in a piece of sheathing there as well. i assume the sheathing there is fine (from what i can see from underneaht), and the leaking was occuring in and around and/or through the flashing.

thanks.

Scuba_Dave 06-26-2009 06:54 PM

Obligatory...Got a pic ?? :laughing:
Is there flashing "built-in" to the chimney bricks?
That is how mine was done, very effective
Is the garage attached to the house?
Different roof level?
Different color shingles as house or the same?
I like architect shingles - look good

Drip edge on the rakes now will prevent water from going in between the 2 layers of shingles

My last house I drilled into the grout (screws) & attached new flashing. I sealed it against the brick - never leaked

If you alread slathered tar over it & it still leaks then more tar won't help. I have found that the tar will harden up in the winter & that is when you will get the leaks

I'd be inclined to strip the area around the chimney
Better to do it right the 1st time

wombosi 06-26-2009 07:04 PM

Quote:

Originally Posted by Scuba_Dave (Post 293525)
Obligatory...Got a pic ?? :laughing:
Is there flashing "built-in" to the chimney bricks?
That is how mine was done, very effective
Is the garage attached to the house?
Different roof level?
Different color shingles as house or the same?
I like architect shingles - look good

Drip edge on the rakes now will prevent water from going in between the 2 layers of shingles

My last house I drilled into the grout (screws) & attached new flashing. I sealed it against the brick - never leaked

If you alread slathered tar over it & it still leaks then more tar won't help. I have found that the tar will harden up in the winter & that is when you will get the leaks

I'd be inclined to strip the area around the chimney
Better to do it right the 1st time

thanks buddy.
will try to get a pic.
garage is detached, probably 6-12 or 7-12.
same color as main house.
i believe thecounter flashing is embedded in the mortar. need a better look tomorrow.

maybe i will install the rake drip edge.

i'm going to put on architectural. i redid the porch, and am matching the shingles to the garage. the main house was done 12 years ago and is fine (three tab - oh well.)

thanks.

i just read a good article on flashing, but still, seems fairly advanced, just knowing how to bend all the pieces. my chimney has a cricket, too, which complicates things (it's near the bottom of the roof.)

burntgoose 06-26-2009 07:42 PM

Two things a roofer needs to know is 1)water runs downhill and 2)payday is on Friday! With all that tar around your chimney are you sure your problem isn't uphill from the chimney? It is not uncommon for the leak to be many feet away from were the visible problem is under the waterproofing membrane.

Ed the Roofer 06-27-2009 03:11 AM

You stated that your roof was really "Blown".

If by that term, you mean really burned out and brittle, it would be extremely foolish to NOT do a complete tear-off of the existing shingles.

Flashing work is something that is done incorrectly over 90% of the time anyways, because there is more to it that slathering roof cement over the gaps and voids in the sheet metal. It needs to be fabricated for the size of the chimney on all 4 sides and certain sections need to have the correct pitch bent into the pieces.

Porous masonry and loose tuck-pointing can account for slow, yet very long term harmful leaks, which occur over extended periods of time due to the organic deck sheathing lumber wicking in the moisture as is transmits it's downward flow from the point(s) of entry.

Yes, photos will help tremendously for a better take on your situation.

Ed

wombosi 06-27-2009 09:00 PM

Quote:

Originally Posted by Ed the Roofer (Post 293639)
You stated that your roof was really "Blown".

If by that term, you mean really burned out and brittle, it would be extremely foolish to NOT do a complete tear-off of the existing shingles.

Flashing work is something that is done incorrectly over 90% of the time anyways, because there is more to it that slathering roof cement over the gaps and voids in the sheet metal. It needs to be fabricated for the size of the chimney on all 4 sides and certain sections need to have the correct pitch bent into the pieces.

Porous masonry and loose tuck-pointing can account for slow, yet very long term harmful leaks, which occur over extended periods of time due to the organic deck sheathing lumber wicking in the moisture as is transmits it's downward flow from the point(s) of entry.

Yes, photos will help tremendously for a better take on your situation.

Ed

thanks ed.
sorry i still don't have photos, but i have a progress report.

started stripping the area around the chimney this morning, found much more rotten sheathing than i was expecting. wound up stripping the entire roof and patching in new 1X6 t&g all around the chimney, and a few other boards here and there that were broken with knots falling out, rotten, etc...

put the eave drip edge up and it started pouring! hastily smacked some tar paper down, and some tarps, and now it's stopped. forecast tomorrow looks mostly dry until the afternoon, with 30% chance.

also took apart the cricket which was infested with ants and eggs. sprayed toxic stuff all over the place.
will have to rebuild the cricket first thing in the AM.

then the plan is to:
ice and water shield first row and around the chimney.
30# felt everywhere else. wrap over the ridge and on top of existing felt on other side ( other side does not need to be stripped, but i will shingle over it).

i'm pretty intimidated by the chimney flashing job. i also don't know how to approach roofing the cricket.

here's how i'm planning to flash the chimney; let me know if i'm on the right track, please:

shingle up to bottom of chimney, install apron flashing which is 4 inches wider than chimney on either side. nail to roof deck, bend around chimney, cutting with pitch of roof.
then bring the s hingles up to the sides, step flashing up the sides.
step flash along the back on both sides of the cricket roof.
roof the entire thing.
then go back and install counter flashing on the base, embedded in the mortar (how do i do this without a fancy diamond tipped saw?).
first piece at base bends over apron, then counter flashing up the sides, bending down.

i guess the key is to not nail or tar these two flashing elements together, as expansion would cause cracks and leaks over time?


any advice on dealing with the cricket and flashing the chimney would be greatly appreciated.
won't be able to get apicture tomorrow, but really need to get this done and in the dry.

thanks!

PS: also got a c hance to replace all the blocking around the chimney, which was rotten, but i couldn't get to when i repaired the wall from the inside and sistered the rafter. chopped off the rotten rafter tail and spliced a new one on - looks great.

Scuba_Dave 06-27-2009 09:29 PM

I'm 20' up the new addition with plywood
We had rain here too
Hoping to get the rest of the plywood up & start roofing tomorrow
I need a cricket on my chimney too
That's one thing they left off when prior owner had the chimney & roof redone

http://www.callfirstcoast.com/images/roofing1.gif

wombosi 06-28-2009 06:07 PM

flashing
 
ok,
so, have all the ice and water/felt paper down, and it can basically rain now and i'll be OK. ran out of drip edge.
tomorrow i go to get supplies, the right size nails for a gun i borrowed, starter course stuff, more drip edge, flashing, etc...

question is, how do i get the old flashing out? should i use a grinder with a diamond blade or something and take out all the morter and old stuff, then put in the new flashing and repoint? will the chimney fall down if i take out all the mortar? is it important to install the counter flashing so that it covers the entire brick, or should it just go in an inch or so?

i think i'm going to use lead flashing, if i can find it by the foot locally.

thanks.

Scuba_Dave 06-28-2009 06:15 PM

My flashing is lead, makes it easy to re-roof
I think it only needs to go in enough to form a seal
I'd say an inch would be plenty
But wait for the Pro's to respond

You can't put flashing up behind the exisiting?
Or is it in really bad shape ?

wombosi 06-28-2009 07:07 PM

Quote:

Originally Posted by Scuba_Dave (Post 294343)
My flashing is lead, makes it easy to re-roof
I think it only needs to go in enough to form a seal
I'd say an inch would be plenty
But wait for the Pro's to respond

You can't put flashing up behind the exisiting?
Or is it in really bad shape ?

i already ripped it all out. i think it was lead, but was in pretty bad shape.
didn't find any step flashing. just a piece of flashing around the chimney on top of the roof deck, but not lapped up onto the bricks, and the counter flashing. was leaking like a sieve all around it.

actually, on one side of the chimney i did find two pieces of aluminum step flashing, looked brand new, not nailed or attached to anything, just kind of fell out. strange. obviously someone had tried to do something...

Grumpy 06-29-2009 09:57 AM

Tear off the roof. Do it, you'll be sorry if you don't. I am not an advocate of lay-overs on steep slope roofs, especially when in your own words "it's blown".

Ice shield around the chimney and any other flashing areas. Do it, it's cheap insurance. Also ice shield your gutter lines and valleys since you are in a snow prone area. Felt the rest of the roof.

Install the new shingles, and good luck with the flashings, if you've never done them before. make sure you have proper ventilation, or your roof won't last.


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