#ROOF CRICKET CODE#

Lay out rafter to the run using the same pitch as the roof.Д¬ut the plywood to the length of the rafter on one side and the ridge length on the other (run length).Дeduct for 1/2 ridge thickness from the rafter and ridge if you're using one.Д¬onsider buying my book ' The Roof Framers Field Manual' to learn more about roof framing.Д¬urrent rules state that crickets are needed for any chimney over 30' wide as long as it doesn't intersect the ridge line. Click image to enlarge.Дetermine the run (1/2 width of chimney). Next add the run 2.296 x 17 =39.032вЂќ the new length of our rafter. If your run happens to be a odd unit like 2вЂ™ 3 ВЅ вЂњ convert the inches to feet by dividing by 12 before you perform your other calculationsвЂ¦.for example 3 ВЅ becomes 3.5 /12 =.

Now if you want a little ridge board youвЂ™ll have to subtract half the thickness of the ridge measured horizontally on each rafter and (subtract half the ridge thickness from the ridge length). Cut two triangular pieces of plywood 24вЂќ long by 34вЂќ wide. Cut a mirror image pair of rafters with a 12/12 plumb cut at the top and a 12/12 level cut at the bottom with a 45 degree bevel.

So 2 x 17=34вЂќ, which is the length of our rafter and also the length of the sheathing on the chimney side. WeвЂ™ll round that number to 17 to make it easier. You can find this number on the framing square under the 12вЂќ mark on the first line of the rafter table labeled вЂњlength of common rafters per foot runвЂќ. It is also the length of the ridge(before deductions) and the length of one side of the sheathing.ДЄll we need to do now is determine the length of the cricket rafter per foot of run. This is the number which we will use to lay out our rafter for the cricket. so a four foot wide chimney has a span of 4 foot and half of that is the run which is 2 foot.

#ROOF CRICKET CODE#

Also assume that the pitch is a 12/12.ДЄlways frame the cricket at the same pitch as the roof and you will be within code guidelines. Assume that we have a chimney which is four foot wide. For example 8/12 roof will be 8 inches vertical to 12 inches horizontal. To begin you must know the pitch of the existing roof which is usually expressed as inches per foot of run. For those of you who donвЂ™t know, a cricket is a type of rain diverter that sets behind a chimney.

Roof cricket