How to fasten shingles on flat roof???

[DocHeb]

When I worked in a lumberyard we always recommended nails 1/4" longer than the total thickness of shingles and sheathing. The old guys there said you needed to go through the wood so the "peaked" wood around the exit site (inside the house) wedged against the nail and helped hold it in. This is anecdotal - don't know if it is based on fact.

 

[patrickg]

What about the nails with the litle ripples (circular ridges)? I've seen those in either zink plate or galvanized. They hold like the devil compared to regular nails. Why wouldn't you want those in a situation like high wind resistance?

Patrick

 

[JATO_RaT]

Dan, 1" nails are fine but will not hold as well as 1 1/4" nails. Even though the 1 1/4" nail penetrates and comes through, thats part of the reason it holds better. It will have a full thickness shaft, not the point embedded in the OSB. I too use 1" nails wherever its exposed.

OSB does not hold a nail as well as plywood, especially 5 ply. OSB's biggest draw back is once it absorbs moisture it will expand losing some of its density as well as pulling itself through the nails used to hold it down.

GlueGuy, once you see that felt on a shake roof, it really is time to replace. Saturated felt just doesnt hold up well to UV. The product which I was refering to is a 36" wide product much like felt. I believe it comes in 50' lengths. It has a paper backing on its sticky side. You peel off the paper as you lay it down. Once it touches itself (sticky side to sticky side) its a bi-itch. A great product to seal alot of difficult areas especially when nails are needed to be used through it. Rat...

Also, shakes are still used but fewer and fewer. 2 reasons I think account for this, 1. other products are filling the market, composition has become more attractive, and cement products have become more attractive. 2. The quality of shake is less then what it was. The trees are smaller and the shakes tend to curl and cup as a result. I still love shake. Putting down heavy shake is almost theraputic for me. The smell, color and choice makes it enjoyable.

 

[StoneHeartFarm]

Nails need to be long enough to penetrate through the wood to get a good grip. Nails with rings or ridges are okay to use, however, if you ever have to take the shingles back off, the job will be a bear. I used 30# felt on my roof as opposed to 15#. The primary reason being that the felt is heavier and doesn't move around as much, so the roof could be felted on Saturday and the shingles applied the following several satudays without the felt moving. Felt tends to sag and slide down the roof in hot weather. The 2 most common reasons here that people don't use shake shingles is cost and the hint of fire danger from drifting embers.

We used to run a wide strip of aluminum sheeting along the eave before starting our shingles. Anywhere from 16" to 36". The shingles would start at the top of this strip. The reason is to prevent ice dams. The aluminum is slick and any ice that builds up will slide off on a sunny day. The problem is that half a ton of ice falling from the eave of a house can do significant damage to anything setting underneath it. The latest technology is to use the Bituthene (sp?) product. The brand name at the local lumber yard is "Ice and Water Dam". The stuff is about 3' wide, has self stick strips and gets nailed down first, with shingles right over. Almost all new roofs are being done this way. Surprisingly, the product works and doesn't. While it prevents water from seeping in where it has been applied, ice dams frequently get bigger than the water and ice proofing. The water gets deeper and deeper on the roof and finally flows over the water proofing, under the shingles and into the attic. The aluminum caused the ice dam to fall off. the Water and Ice proofing does not.

RCH
Your bottom edge of shingles isn't sealing? Usually, we run a double bottom course, one shingle upside down and one right side up. The upside down row is a starter row, because the backs of the 2 shingles stick together, it makes this starter row twice as heavy, which helps it to stay down. About the only thing I can suggest is to get a gallon can of roof sealant and smear it under the shingles to help them seal. Doing it on a hot day will help. If the tube stuff isn't working, that's about the only thing I can think of that might help.

SHF

 

[RPM]

Nails will hold better if they fully penetrate the plywood or OSB. Reason is that the nails driving through the wood force the fibers apart - it is the resulting compression of the fibers on the nail that holds it there.

If the nail penetrates then the compression acts along the whole length of the nail ...

The rings that you get on nails are only any good if the nail is loose - the primary anchoring force is the compression of the wood on the nail. Good idea on decks and stuff where the wood may decay around the nail and loosen it up - but probably not shingles.

 

[Rch]

SHF, It's not just the bottom row of shingles that aren't sealed down, it's the bottom edge of many of the shingles all over the roof. I don't know the brand of shingles nor the weight of the underlying felt. The house has the same shingle and that has not been a problem. This is primarily on the lower (steeper) part of the gambrel roof on the north side (less sun).

RCH

 

[StoneHeartFarm]

RCH,

Are the corners on the tabs curling slightly?. When you stand back and look at the roof, does it look "patchy"? (Does it have spots with curling shingles and spots where the shingles look normal, "patches").

The reason I'm asking is that I have noticed the same phenomenon on a number of roofs. All 3-8 years old, and here are patches of curling shingles. The first time I saw it, I guessed the roof at about 15 years old. I was surprised to be told it was 5 years. Since then I have watched carefully and seen several other cases. Frankly, I have no idea what is causing it, but I suspect faulty shingles. Probably out of the same factory during the same period. If you look carefully and think about it, you can see where the roofer opened different bundles. Typically, the roofers lay several rows at a time, so an open bundle will be in a squarish patch rather than just run straight across in a line.

What I'm not sure about is the cause of the faulty shingles. I don't know if it is from the factory, shipping or storage. Shingles sitting in the back of a semi in the hot sun are going to be different when delivered than those dropped at the yard in the middle of winter or cool weather.

Until the roof starts leaking, it doesn't sound like there is much to be done, and when it does start leaking, you face the task of re-roofing. For the moss buildup, you might try some of the copper attachments. These are small formed sheets of copper that slip under the shingles. Apparently there is some chemical action between the copper, weather and roof that kills moss and keeps it from growing. Some of our roofers have told me they are using copper clad nails now to do the same thing.

SHF