Cricket talk

[jimAKAblue]

I happened to follow a link about "how to build a cricket". http://www.hammerzone.com/archives/r...esm/frame.html

The guy was an engineer and talked about how difficult the level cuts are on the crickets rafters...so it's obvious that he's no carpenter..but overall, his article would make sense to the average novice.

Anyhoo...

I wondered how many here would bevel the rough plywood sheathing to get a "tighter joint"? I'm trying to imagine the formula for determining the total overall lengths and sizes of the triangular shaped pieces and I can't for the life of me think of a reason why I'd go to that extreme...unless I was bored and getting paid hourly and wanted to beef up the bill.

More importantly though. We always extended the cricket beyond the edge of the chimney by at least a couple inches. We did this up there in ice dam land: Michigan. We pushed the cricket out beyond the edge of the chimney to avoid the choked exit that the blogger creates with his technique. Down here in the hot south, I've never seen the cricket extended and I'd be labeled a hack for doing it.

Oh...one more thing. I've built hundreds of those crickets and I never bothered figuring out what the slope was. I'd just whack the ridge to a length that looks high enough and fit the rafters by measurement. I'd normally whack the rafter in by eye but if I needed to put a square on it for any reason, I'd just use the "total rise and total run" as my numbers for the square. I never bothered formulating it into the base 12 formula.

One last thing. We always kept our framing away from the masonry by 1" for fire code reasons. There was a poster in here yammering about needing 1/2" clearance for contraction and movement reasons. Its a question worth discussing.

[dlhunter]

Jim,
I followed that same link and came to the same basic conclusions as you. The only difference is that I would actually calculate the rafters but probably only because I usually had a cm in my pouch so it only took me 2 minutes to figure. I always would extend the cricket past the chimney at least 2" past finish material. As far as the beveling plywood goes that's just a waste of time in my opinion. I did work for a guy who on my first day told me how he wanted hips and valleys beveled on the tops and the plywood that landed there beveled as well. As soon as he left the lead guy said to me "yeah he's nuts. We don't do that but if he asks just tell him we did. He can't see it from his truck"

[tjbnwi1]

I had to do a chimney cricket to meet code for a sale after a home inspection, Had to look at some other items, measured the roof while I was there, 5/12 main roof, 5' wide chimney.

Got the ok to do the job. Cut and built the cricket on the bench in my garage, went to the job, stripped back the shingles, removed some siding, nailed the frame in place, installed the pre cut sheathing (no bevel), laid the shingles with tins, installed the siding.

It was most likely me yammering. It wasn't expansion and contraction, it was sway in the wind.

Tom

[jimAKAblue]

Tom, I used to prefab the crickets and hand them up to the guys to nail on the roof. Then, after doing it that way for a dozen years, I just whacked them in place as I was sheathing the roofs. I don't like wrestling something 5' wide if its up a ladder etc.

I did experiment with building reverse layons down and shipping them up with the crane. I tried several different variations: exact ridge length vs shortened ridge length, etc. My conclusion was that it was effective if I framed it early enough in the job process, using the clear first floor deck as the staging area. I wasn't really keen on doing that because it disrupted some of our other processes.

Also, the truss companies rarely shipped us layon stepped up trusses. Again, I experimented with pre fabbing them and again, I quickly determined that the best staging area was the empty first floor deck. After a little evaluation, I again determined that I'd rather just lay them on, in place. There were a variety of reasons for why I chose that system but I wouldn't be able to remember all the variations and reasons.

In my early days, I liked prefabbing and figuring the bevels, lengths etc. In my older days, I just wanted to get er done and I typically chose the path of least resistance LOL.

[jimAKAblue]

Jim,
I did work for a guy who on my first day told me how he wanted hips and valleys beveled on the tops and the plywood that landed there beveled as well. As soon as he left the lead guy said to me "yeah he's nuts. We don't do that but if he asks just tell him we did. He can't see it from his truck"

LOL, I've worked for a few guys like that.

One of my earliest memories of figuring out small rafters was when I framed my first house. It had hip returned eaves and I couldn't conceive of how to create that small rafter, even though it was just a rafter with a 1' run. I do remember getting them built and I remember beveling the top plywood. I was very proud of myself that I could use the framing square to figure and mark the ply cuts for the hip roof and especially the "starter board". In those days, we didn't use metal drip edge and we started every roof with a 1x6 starter board that was hung past the fascia by 5/8". On a hip, it had to have a finished appearance, so it had to be beveled and mitered.

It was all downhill after that LOL. That was in 1980 or something like that.

[Mark Parlee]

Jim
here is how we do it.
Extend past the chase at least 4 to 6"
Leave the shingles on to waterproof until the roof is done and tied in; who cares if the old shingles are under the new framing.

[ThingOfBeauty]

We also extend past.
Some remodeling crickets get to be very big (not at chimneys, but where additions tie in), we put 8"-12" wide openings sometimes, if it looks like a leaf-catcher.
I've had a lot of framers & roofers look at me like I'm crazy, but after seeing a dozen of them full of leaves and 3" deep in water, it gets to be an important detail.

[tjbnwi1]

Jim,

It was just easier for me to do this one in the shop. An 8' ladder got me on the roof so it was no big deal.

Mark,

If I would not have stripped the shingles, I would not have had enough to finish the job. Sometimes on a repair, ya gotta do what ya gotta do.

Tom

[Mark Parlee]

Tom
I do understand that one.

[jimAKAblue]

Mark, I'm not opposed to laying over the old shingles either.

Doug, on all the new homes I framed, we also ran the sidewall crickets past 12". Otherwise, like you mentioned, they'd be a perfect collector of leaves and ice in the fall/winter. I've done more than one major roof repair because the framers brought it down to a point. It looks pretty in the rough, but all he l l breaks loose after the first winter.

[Graacc1]

GEEZ!

How come all my chimneys are brick?

Geoff

[Mark Parlee]

Geoff

do you have crickets om your brick chimneys; I see a lot that don't

[Lavrans]

Geoff

do you have crickets om your brick chimneys; I see a lot that don't

Huh... Is that because there's that handy firebreak gap, so the water can just drain down the chimney? ;)

[TWhite]

Shhh....I charge extra for the interior fireplace waterfall!

[Hearthman]

You can frame a cricket with one 2x4: layout dimensions per IRC using roof pitch and chimney width. Cut ridge with taper cut to make ridge level with bevel screwed into roof. Layout plywood triangles to the height and width of the cricket then cut out for the ridge pole at the peak. Use this as a pattern for several more. Each successive frame is the same angle but just shorter as it marches up the roof. Three to four should do it. They will mimic gunwales in a boat. Use scrap 2x4s as blocking between the frames down near the roof deck and ridge. No fancy cuts except on the ridge pole uphill. That's it. Measure the plywood sheathing and cut a rectangle to the ridge by the base then split it diagonally. That makes the two triangular decks. Screw to framing. No need to bevel edges of plywood. Cover cricket and valleys with ice dam membrane. Install step flashing up against side chimney, then shingle. I use sheet lead or 16 oz. copper. Cut counter flashing into reglets in the mortar joints and point flashing in place using lime mortar. Alternate method is to cover cricket with standing seam copper with soldered joints.