How to fasten shingles on flat roof???

[DrDan]

I have a flat roof with a pitch on a chicken coop I just finished. Want to put shingles on it since I have some left over from another project but really wonder how you fasten the top row of shingles without putting nails right out in the open where leaks will start.

Also what is the reason for roofing felt? I have some and can put it on, but just wonder why you can't put shingles right over OSB board.

Thanks

Dr Dan

 

[JATO_RaT]

A flat roof with a pitch? A shed roof perhaps is what you meant where you have a slope from front to back. A gable roof where you have a center peak, at any rate, shingle roofs really need to be on a 3/12 pitch to be effective. A 3/12 is a 3" drop for every 12" run or horizontal distance. Typically there is not a problem with exposed nails for the cap shingles. If you felt the need, there are now elastomeric roofing sealants/adhesives available that could possibly do the job without nails, but personally, I would still opt for nails since the expansion/contraction of asphalt products on the roof is significant. Felt is used for both a vapor barrier and additional waterproofing particularly during application. Rat

 

[GlueGuy]

The felt is the primary water proofing member of a roof system. The shingles primary function is to protect the felt.

The GlueGuy

 

[StoneHeartFarm]

Dr Dan,

Put on the felt, it only takes a short time. You'll appreciate it when you have to strip those shingles back off. Most shingles are designed to melt somewhat in the hot sun and stick together, forming a solid mass. Seems to me the felt is there to make it easier to remove the shingles later, since they'll be stuck together and not stuck to the OSB. The felt also provides a second layer of defense against leakage, and a slight cusion to the shingles when you're up there walking around on them. I assume the top row you are talking about is a "cap row", I don't know if you have a shed type roof (one slant only) or a standard roof (inverted "v"). The cap row is usually smaller than the other shingles. You have to cut full sized shingles down (in 1/3rds. Just follow the slots already cut in the shingles). If you look at the back of standard shingles, there is a seal strip (covered with clear plastic tape). You want to save that part as part of your cap shingle when you cut them down. Start at one end of your peak (lets say the left hand side). Pull the strip off the back of your cap shingle, lay it in place and put 2 nails in it at the end opposite the seal strip. Peel another cap piece and lay it over the first, with the seal end covering the nails on the first piece, nail it just like the first one. By repeating this until you reach the far end, you cover all the nail heads on the cap shingles except for those on the end. On the last one, I've always tarred the heck out of it and just stuck it down without nails. Seems to work just fine. The first good hot day, the shingles should start sticking together.

Hope this helps /w3tcompact/icons/smile.gif

SHF

 

[DrDan]

Yup that's what I've got a shed roof. Thank God it's only 4' X 8'! In this heat we'd probably be stuck to the dang shingles too. Man what a guy will go through for a few fresh eggs everyday!

Thanks Guys,

Dr Dan

 

[skent]

Roofing shingles expand and contract at different rates than the wood under them. They try to stick (self-sealing). If you put then directly to the wood (w/o felt) they will try ti stick to the wood and end up not making a good seal (always being pulled and pushed with heating and cooling). Felt is not that expensive and will increase the life of the roof. Small roofs (like a dog house) generally do not have the need for felt though.

Steve

 

[JATO_RaT]

Glue Guy, I would disagree with that statement about the felt being the primary water sealer. At best it is secondary, at worst it becomes the primary. Reroofs over existing typically leaking rotting composition roof types don't necessarily have to have a layer of felt under them. Its advisable, but not required. Actually, I not only won't do reroofs, but time after time it is shown that reroofs will not last as long as roofing over a smooth surface like plywood, OSB, or like they used to use, 1x8. This is proven many tmes over when a previously remodeled home needs a new roof. The reroof is in far worse shape then the roof layed over the remodel. Wood shingles do not allow for felt paper period and its use would surely rot the cedar shingle quickly from the bottom side (thus the skip sheating used as the base for shingles). Shake roofs are about the only roof that heavily rely on 30lb felt to maintain roof integrity from decaying shingles.
Some tips: use 30lb felt. Why? Because the 15lb won't stay put without a thousand nails even in a light wind. Its about twice the price, but still minimal for the whole job. For really troubling areas like low slope valleys, low pitched roofs or areas prone to ice dams, use a product like ***** (bituthane) sp? or Grace water seal. It can be nailed through a thousand times and still not leak. Nails hold better then staples but staples require less frequent (and faster) loading. I always use nails, an air nailer, 1 1/4" nails are good for new roof. Rat...

 

[DrDan]

The dang chicken coop is done!!!! I only had a 4' X 8' roof to shingle (Thank God) and was trying to keep costs down so we had two packages of shingles - one gray and one black. LOL I'll never do that again! Used some 15# felt we found up in the storage building (was used by some contractors for awhile and they vacated and left stuff laying). Anyhow, we alternated every other shingle gray then black then gray, etc. Staggered shingles 6" and ran into trouble at the ends with one row that would have taken about a 2" wide strip. Oh well it came out with some really neat geometric patterns and it should keep the biddies warm and dry. I'll post a picture later. It is a really neat coop. I got the plan off the net - it was a coop used in the Netherlands. Will house 3 full sized birds or 6 banties. Kinda prefer the Buff Orphingtons. With em eating all the grubs and other bugs the eggs are wonderful! Well next it's a small hog shed to raise two or three a year.

Dr Dan

PS Is there a reason to use 1 1/4" nails when the OSB (2 layers) is only 1" thick? I used 1" nails cuz I didn't want to hit my head on nails sticking through.

<P ID="edit"><FONT SIZE=-1>Edited by DrDan on 07/01/01 02:53 AM (server time).</FONT></P>

 

[Rch]

Rat et al, I've got a gamble roof on a barn and the asphalt shingles on the north side keep getting blown half way off, i.e. the edge doesn't seal, the wind lifts the shingle up despite a extra dollop of DAP asphalt sealer(in a tube like caulk) and lifted the 3/4" roofing nail almost out. Undeneath is OSB sheeting, I think 1/2". Is there something about OSB (oriented strand board) not holding on to nails ? Admittedly,It was a hell of a wind and that potion of the roof gets the brunt of a wind out of the northwest. These were common galvinized roofing nail that looked like they were dipped in zinc. The north side of the roof doesn't get that punishing sun and you can see dark fungal staining and even a few colonys of moss. It's an unheated building.

RCH

 

[GlueGuy]

Rat,

I was going to argue with you, except that you mentioned shake roofs as needing the felt (30#). There are still a lot of shake roofs out here. They are getting more rare, but it is still predominant. They absolutely need the felt. On our last home (before we re-roofed with composition), I was doing an inspection, and found one old shake that had worn completely through (could see the felt). That's when I decided we needed a new roof ASAP! Never got a leak though; because the felt was still intact.

But, I agree, the equation is a bit different with compostion roofs. I still believe in the heavy felt (30#), regardless of roof type.

Were you meaning bitumen, or is this some other stuff?

The GlueGuy