Chimney Chase

here's an example of a typical chimney

chase on the side of a house not a lot

of masonry chimneys built anymore so

this is a very common practice there is

a problem with this type of installation

as far as brick veneer is concerned

sometimes that I'd like to make you

aware of in this particular picture

you'll notice the little cricket the

small roof behind the chimney it's

properly designed in that there's a

brick pocket so that the masonry can

actually turn the corner and go around

behind the chimney that's not normally

the case or many times I should say

that's not the case what I see in

construction on a regular basis is that

cricket coming all the way over and

coming in contact with the backside of

that chimney chase then the brick are

just laid on top of that small roof

which is not enough support to carry the

weight of masonry this is what happens

typically if you don't have enough

support on the backside of a chimney

it begins to list toward the home has no

choice it's a two-fold problem in that

as it leans toward the house somewhere

around gutter height or soffit height a

crack develops as the chimney leans over

against the roof on the exterior side of

the chimney the crack now allows water

to just pour into the chimney chase so

the befuddle homeowner is looking around

trying to figure out where's the water

getting in let me replace the flashing

around it let me see if it's raining

down the cap or whatever and what it is

the chimney has actually began to lean

toward the home opening up the crack as

you see it here and what I'm going to

get into now for a moment might be

meddling because I'm going to talk about

you carpenters for a bit but it has to

be prepared properly as far as the

carpenter work is concerned in order for

it to carry the load when the mason

shows up this is what you commonly see

on a chimney chase as far as framing is

concerned in order for this chimney

chase to come up the side of the house

you see how two rafters there have been

cut off

two single rafters on each side of the

opening are now accepting what is a

double header on the backside that's

normally what you see but it does not

satisfy the code in any way it won't

carry the way to masonry what it should

be is tripled up rafters of both sides

of the chimney chaise and the header in

the back of the chimney as you see

depicted here this will carry the load

of the masonry as the chimichurri

masonry weighs 40 pounds per square foot

what would you say that chimney weighs

would you park your BMW in a garage

obviously somebody wanted a fireplace in

the bonus room and that's great but you

have to wonder when you drive down the

street and take a photograph like this

is there proper support for that chimney

just to give you an idea of about how

much it weighs we did some calculations

in a ways about what a Crown Victoria

and a half would weigh obviously a lot

of weight if you don't take into

consideration carrying that load this is

what could happen to you at one point

there was a chimney on the top of this

house and a chimney chase you see where

it is now thankfully the homeowner and

his wife and kids weren't having a meal

on the deck at that point the Mason said

well I put a couple of steel angle irons

down both sides of the chaise the

problem was it wasn't properly attached

to the chimney chaise and didn't do its

job the code mentions two different ways

that you can carry the load of brickwork

in a gable setting or around a chimney

for that matter this is directly from

the code the IRC and either the triple

drafters that you see on the left side

there or the lentil carrying the load

would do the job one thing you might

keep in mind to make sure you have

proper drawing to make sure you get the

smoke out of the house the chimney

should be at least two foot above ten

foot over now what that means is at any

point that you can make a level line

from the roof over to your chimney

that's at least 10 foot long

then the chimney should be at least 2

foot higher than that point but the code

also mentions that at the point where

the chimney comes through the roof

whether it be on the side of the house

as you see here or up at the ridge the

chimney must be at least 3 foot tall

what that does is give you a buffer or a

little extra room in case you have a

chimney fire now that fire would be at

least 3 foot above the shingles which

would obviously be a fire hazard so just

keep those things in mind as far as

carrying the weight of brickwork on a

chimney chase